The URL can be used to link to this page

Home My WebLink AboutAPA2989Biological Services Program FWS/OBS-80/09 June 1980 GRAVEL REMOVAL GUIDELINES MANUAL FOR ARCTIC AND SUBARCTIC FLOODPLAINS lnteragency Energy-Environment Research and Development Program OFFICE OF RESEARCH AND DEVELOPMENT U.S. ENVIRONMENTAL PROTECTION AGENCY and Fish and Wildlife Service U.S. Department of the Interior DISCLAIMER The opinions, findings, conclusions, or recommendations expressed in this report are those of the authors and qo not reflect the views of the Office of Biological Services, Fish and Wild- life Service or the Office of Research and Development, U.S. Environmental Protection Agency. INTRODUCTION A study was initiated in mid-1975 to evaluate the effects of gravel removal from arctic and subarctic floodplains in Alaska. The primary purpose of the project was to provide an information base to assist 'resource man- agers in formulating recommendations that would minimize detrimental environ- mental effects of gravel removal from floodplain material sites. To achieve this objective 25 material sites were studied by a team of scientists and engineers. Three major products resulted from the study. They are: (I l a Technical Report presenting synthesis and evaluation of the data collected at the sites, (2) a Guide I ines Manual that aids the user in developing plans and operating material sites to minimize environmental effects, and !3) a Data Base filed with the U. S. Fish and Wildlife Service in Anchorage con- taining raw and reduced data, aerial and ground photographs, and other relevant material from each site. This report is the Guide I ines Manual. APPLICABILITY OF THE GUIDELINES It is important to recognize that the guide! ines contained in this manual were developed from a study of 25 floodplain material sites in arctic and subarctic Alaska. Therefore, they deal neither generally nor specifi- cally with material sites in upland or coastal situations. Similarly, they do not include evaluation of the relative acceptabi I ity of uti I izing an existing active or abandoned material site or an abandoned structure contain- ing gravel lsuch as a dri I I pad or airstrip! rather than a floodplain site. This should not be interpreted as recommending sites in floodplains over other locations. WHEN A NEED FOR GRAVEL HAS BEEN IDENTIFIED, ALL ALTERNA- TIVES SHOULD BE CONSIDERED. ONLY AFTER A FLOODPLAIN HAS BEEN SELECTED FOR THE PROPOSED MATERIAL SITE DO THE GUIDELINES CONTAINED HEREIN BECOME APPLI- CABLE. However, if used cautiously some guide I ines may be uti I ized in other site and regional situations. The 25 material sites exhibited a range of variation in site age, gravel mining method and location; and river configuration, origin, and size. Selected sites were minimally affected by complicating factors such as nearby bridges, culverts, vi II ages, and other material sites. The latter case is significant in the application of these guide I ines. On large proj- ects it is sometimes necessary to locate a series of material sites in close proximity along the floodplain of a river. The effects of multiple material sites in a floodplain were not evaluated in this study. Hence the appl i- cation of these guidelines to multiple site projects must recognize this shortcoming. The user should be thoroughly fami I iar with the contents of the Techni- cal Report to give perspective to the guide I ines for their effective use. THE GUIDELINES ARE DESIGNED TO DIRECT THE PROCESS OF IDENTIFYING, PLANNING, PREPARING, OPERATING, AND CLOSING MATERIAL SITES; THEY ARE NOT MEANT TO BE USED AS STIPULATIONS TO BE USED IN EACH AND EVERY CASE. It is essential that the user of these guide I ines consider each materi- al site individually. Identification of unique characteristics may require that certain guidelines be ignored or interpreted differently, or different combinations of guide I ines be considered. This manual is intended for use by all individuals interested in floodplain gravel removal. GRAVEL REMOVAL METHODS AND CLASSIFICATION A variety of gravel removal methods and river characteristics are covered by this manual. In general, these methods and river characteristics consist of: I. Scraping exposed or vegetated gravel from active and inactive flood- plain and terrace deposits. Scraping usually does not involve work- ing in active channels. 2. Pit excavation of vegetated gravel deposits located in inactive floodplains and terraces. 3. Dredging from the bed of active channels of large and medium-sized rivers. 2 SUMMARY OF PROJECT RESULTS AND CONCLUSIONS Study of 25 floodplain material sites has shown that disturbance result- ing from gravel removal operations can be minimized. Two gravel mining tech- niques were used at the study sites, scraping of surface or near-surface deposits and pit excavation of deep deposits. In general, approaches to minimize environmental changes caused by scraping included maintaining buffers between active channels and the work area and avoiding: • I nstream work • Mining to depths and in locations that induce permanent channel shifts or ponding of water • Clearing of riparian vegetation • Disturbance to natural banks Large rivers and braided rivers generally provide the most accessible gravels for scraping. Gravel mining using scraping technqiues in these areas frequently resulted in the least environmental changes. Pit excavations resulted in permanent loss of terrestrial riparian habi- tat, however, many pits increased local habitat diversity. These newly created habitats frequently received concentrated uti I ization by local fauna, particularly fish, waterfowl, shorebirds, and furbearers. Large quantities of material were excavated using pit mining techniques. Pits that were located on the inactive side of the floodplain, and were separated by vegetated buffers in the range of 50 to 100m, generally did not influence active channel hydraulics. Pits were found to be most beneficial to local fauna when they exhib- ited the following characteristics: 3 • 2 ha or more in size • Contained diverse shore I ine configuration • Contained diverse water depths • Contained islands • Contained an outlet connected to active channels 4 PROCEDURES FOR GUIDELINE USE To use this manual it is necessary to acquire information on site loca- tion, operation, and environmental conditions. The information consists of descriptions of the site and gravel removal methods that wi II allow predic- tion of floodplain changes. The manual is divided into seven sections based primarily on the order in which a site wi I I be selected, reviewed, and worked !Figure I I. Although site selection is the primary topic of Section I, much of the information in the other sections is also valuable in selecting appropriate mining locations and methods. For this reason, the entire manual should be read and clearly understood before deciding on a final work plan. For ~xample, much of the information in Section VI; SITE OPERATION can be valuable in determining where selection of a specific method or location may increase the amount of avai I able material while decreasing environmental alteration. After the guide! ines have been thoroughly reviewed, it is recommended the sequence presented below should be followed. SITE APPLICANT I. Identify suitable sites using the procedures described in Section I. 2. Develop a tentative plan on how and where to remove the required gravel within the proposed site. Acquire field data needed to complete Site Planning as described in Section II. 3. Evaluate the proposed plan by applying the appropriate guide I ines from the SITE PREPARATION, SITE OPERATION, and SITE CLOSURE Sections. This may identify alternative methods or locations and potential problems, speed the review process, and lead to more efficient site operation. 4. Develop a formal Work Plan, as described in Section I I I, to be sub- mitted to the appropriate agency. 5 Problem Generll Sit• Selection Fk:Jodplain c;. .... Remowll Guidelinn ........ I- I I I I I I I I I I I .,.I e 1 0. 0. :J! 'C I ~- cl g I .111 ]I E I I ~-~e;;cy-Si~ i I Visits I I I ---,--- 1 MATERIAL NEED IDENTIFICATION OF SUITABLE SITES Section I WORK PLAN DEVELOPMENT Section Ill submit _ .,!P.£!0.!!:11 ___ 1 I SITE PREPARATION SectionV 1 ____ -f-----'S~I~T=E~O~P=E'-'R!"A':'T._,IO"-'N'------I Section VI : _____ ...1·----~S~IT~E:..:C~L~O,s..,u.,R._,E,__ __ _ Section VII Figure I. Gravel mining planning and implementation. 6 5. Work and close the site in accordance with the appropriate guide I ines and approved Work Plan. SITE REVIEWER I. After receiving a work plan completed in accordance with Sections I through I I I, evaluate the plan and site location for the presence of significant environmental features identified in Section IV. 2. Visit the site to evaluate the technical feasibi I ity, proposed bounda- ries, habitat quality, and possible environmental concerns. 3. Use Sections V through VII to evaluate the Work Plan and suggest modifications, if appropriate. 4. Following approval, conduct site visits during operation and closure to check adherence to the approved Work Plan. 7 Gravel Removal Guidelines Identification of Suitable Sites Section I Page GENERAL GUIDELINES . II SPECIFIC GUIDELINES II Technical Characteristics of Alternative Sites . . . . • . . . . 12 Areas or Species of Special Concern . . . • . . • . . . . • . . 12 Technical and Economic Criteria .• 13 Other Environmental Criteria • . . 14 VERIFICATION OF SITE ACCEPTABILITY • . . I~ Identification of Suitable Sites Section I A. GENERAL GUIDELINES A number of factors influence the suitabi I ity of a gravel removal site. Among these are: • Technical Requirements-such as quantity and quality of avai I able material, required processing )washing of fines I • Economics-such as hauling distance, and site preparation and rehabi I itation requirements (overburden removal, river-training structures, and site grading) • Environmental Characteristics-including location within jhe f load- plain, and biological characteristics of the site Many projects require more than one type of material, and these types often wi I I not be avai I able from a single material site. Linear projects such as pipe I ines and roads wi I I require sites spaced along their length. In regions where winter construction activities are required, stockpi I ing of gravel in summer may be necessary to provide material with lower moisture content. B. SPECIFIC GUIDELINES Because of the need to incorporate technical, economic, and environ- mental factors, siting decisions must be considered on a case-by-case basis. However, a sequence of four levels of decisions should be uti 1- ized in site selection. AI I levels should consider both previously undis- turbed sites as wei I as previously mined sites. There may be occasions I. IDENTIFICATION OF SUITABLE SITES when previously mined sites are more suitable because of the presence of access roads, airstrips, removed overburden, and existing unused stock- pi led material. A pre I iminary site visit is appropriate to provide input to the follow- ing decisions. I. Decision I -Technical Characteristics of Alternative Sites Two initial steps are important in the site identification process. a. Determine that the area can provide material meeting the technical and volumetric requirements of the project. These requirements must be obtainable within suitable buffers !refer to buffer recommendations in Section VA 3 and Appendix AI. b. Determine if more than one specific site that meets these requirements exists in the area Failure to determine avai labi I ity of suitable material can result in unnecessary economic cost and environmental damage if initial mining activities show a site to be unsuitable. It is desirable to identify alternative sites in an area of interest because not alI sites wi I I be acceptable. 2. Decision 2 -Areas or Species of Special Concern The alternative sites identified in Decision I should be evaluated relative to their disturbance of the features I isted below. A site affecting these areas should be modified, or in some cases dis- carded, to minimize or eliminate any effect. a. Threatened or endangered species and their habitats that are deemed essential to the survival or recovery of these species that are recognized by Federal and State governments. A cur- rent I isting of species and information as to their distri- 12 I. IDENTIFICATION OF SUITABLE SITES but ion may be obtained from the U. S. Fish and Wildlife Service or the State Fish and Game agency. Sites affecting these species or their habitats may be prohibited, or require substantial justification. b. Habitats I imiting local populations !such as fish spawning and overwintering habitats, Dal I sheep lambing areas or raptor nesting habitats!. Sites directly affecting these habitats should not be considered further unless alternate sites are not avai !able. c. Undercut vegetated banks and associated riparian zones d. Incised vegetated banks and associated riparian zones, except for proper I y uti I i zed access by f i I I ramps e. Springs f. Active channels in smal I rivers of meandering, sinuous, and straight configurations g. Wetlands-The primary criteria most frequently used in wet- land definitions include presence of water-saturated soi I con- ditions, and vegetative communities adapted to such con- ditions. For current definition, delineation and jurisdiction refer to local offices of the U. S. Army Corps of Engineers. h. Other Federal, State, and pr1vate lands with special use and regulation such as wilderness areas, parks, wildlife refuges, archaeological areas, and historical landmarks 3. Decision 3 -Technical and Economic Criteria Following the determination that suitable material can be obtained from one or more sites without disturbance to areas or species 13 I. IDENTIFICATION OF SUITABLE SITES of special concern, strong emphasis should be placed on selecting an economical site. Factors influencing this decision include: a. Amount of site preparation and rehabi I itation required. For instance, it is desirable to minimize: • Haul distance to project site • Vegetation and overburden removal • River-training structures and bank protection devices • Length of access route • Crossing of active drainage or channels b. Matching site operational requireme~ts to avai !able equipment c. Abi I ity to work the site in a dry condition 4. Decision 4-Other Environmental Criteria If at this point two or more sites are suitable, then the following environmental factors should be considered in final site selection: a. Minimize disturbance to fish and wildlife habitats. For ex- ample, if sufficient gravel deposits are avai fable elsewhere, active or high-water channels and vegetated habitats should be avoided. b. Minimize disturbance to local visual and scenic quality. For example, locate sites in areas away from pub! ic view or where they wi II be least visible; insofar as possible select loca- tions that wi I I a! low one to preserve the character of the area. 14 I. IDENTIFICATION OF SUITABLE SITES c. Bed load replenishment rate should be considered in site selec- tion if the I ife span of the site is to cover several consec- utive years, even if there wi II be inactive periods. Glacial and mountain origin rivers, particularly near headwaters, have potential ty higher replenishment rates than rivers originating in foothi Its or coastal plains. d. Projects requiring large gravel quantities !roughly 50,000 m3 or morel, should consider the following: • Scraping of unvegetated, mid-channel bars and lateral bars in braided rivers, and medium and large split channel rivers. This recommendation should be followed as long as suitable buffers lsee Section V A 3 and Appendix Al can be maintained. • Pit excavation in terraces or inactive floodplains, as long as sufficient buffer is maintained between the pit and the active floodplain e. Projects requiring less than 50,000 m3 should consider: • Scraping unvegetated mid-channel and lateral bars in braided rivers and large and medium split channel rivers; this recom- mendation should be followed as long as suitable buffers can be maintained • Scraping point bars of large and medium meandering rivers • Scraping in terraces or inactive floodplains C. VERIFICATION OF SITE ACCEPTABILITY Before proceeding with SITE PLANNING, review the selected site on the basis of the entire Guide! ines Manual. Give special attention to the 15 I. IDENTIFICATION OF SUITABLE SITES SITE PREPARATION and SITE OPERATION sections. The matrix tables within SITE OPERATION specifically present recommendations about gravel deposit type and location, and mining method. The purpose of this verification review is to minimize decision-making delays resulting from failure to consider site specific features. 16 I. IDENTIFICATION OF SUITABLE SITES 81 S3Nil30in9 JI~IJ3dS · S3Nil30in9 lV~3N39 II uon~as 6U!UUeld 9I!S Site Planning Section II Site planning should incorporate the SITE PREPARATION, SITE OPERATION, and SITE CLOSURE guide! ines presented in Sections V, VI, and VII. A. GENERAL GUIDELINES I. If the technical method of gravel removal has not been determined during site selection, then either scraping, pit excavation, dredg- ing or a combination can be chosen by reviewing the SITE OPERATION guide! ines 2. Design of the specific work area boundaries should incorporate the fat lowing factors: a. Site configurations should avoid use of long straight I ines and be shaped to blend with physical features and surroundings !Figure 2l: • Scraping point bars of meandering and sinuous systems to maintain slopes and contours resembling those of the natural bars • Scraping mid-channel and lateral bars of braided systems, to maintain natural gravel bar shapes • Excavating pits to provide irregular shore! ines with curved configurations, islands, spits, and diverse shore! ine depths b. Vegetated areas should not be disturbed when sufficient quanti- ties of gravel can be obtained within prescribed buffers in unvegetated areas of floodplains !buffers guide! ines are in Section VA 3 and Appendix Al I I. SITE PLANNING 18 c. When vegetated areas cannot be avoided, it is usually desir- able to locate material sites in large stands of homogeneous mature vegetated areas d. The site should be located on the same side of the floodplain as the material use point. This wi II minimize the need for crossing of active channels. 3. AI I work scheduling should attempt to avoid conflicts with sensi- tive biological events and extreme hydrological events. Figure 2. Examples of desirable material site locations and configurations. a. In general, work should be scheduled to avoid peak biological events, such as local fish migration and spawning, and bird and mammal breeding, nesting, and rearing-of-young. For ex- ample, site clearing of vegetation should occur in fal I to avoid the sensitive spring and early summer avian nesting season. Occasions may occur when gravel removal operations should be suspended to avoid disturbance to an essential biological event. 19 I I. SITE PLANNING b. Where site work is occurring in the active or inactive flood- plain, scheduling should allow for work suspension and removal of equipment, materials, and stockpiles from the floodplain during spring breakup or other predictable flood events 4. After incorporating the conclusions from the four levels of deci- sions from Section I into a final site selection, a site investi- gation (described in Appendix Bl should be conducted to: a. Verify that the candidate site can produce the quantity and quality of desired gravel b. Collect hydraulic measurements such as discharge, channel cross sections, and bed material size distribution whenever possible to assess the hydraulic conditions of the natural channel (see Appendix Bl. c. Determine the presence or absence of I imiting fish and wild- 1 ife habitat within the project site. Analysis should be based on annual biological requirements I i.e., fish spawning and overwintering habitat!. d. Flag site boundaries and buffer locations in preparation for an agency site inspection. Flagging should be highly visible, of weather resistant material, and maintained through site operation and closure. • Mark site boundaries on mature trees in timbered areas with some highly visible material (such as paint or cloth material l. • For flagging in the open-water season use 1-m metal stakes or rods driven approximately 0.5 m into the ground with a red flag of approximately 15 x 15 em attached 20 I I. SITE PLANNING • At sites to be opened during winter, alI work area locations lsuch as active channels, buffer locations, vegetated areas, and gravel deposits) should be surveyed from reference points established during the initial open-water site visit !Figure 31. Reference points should be selected so they can be found in heavy snow cover during future site preparation. Establish- ment of these surveys wi I I reduce accidental damage to active channels and buffer zones. Three or more temporary bench marks which can be located during winter Do a summer trave or stadia survey to locate material site boundaries ~: Figure 3. Schematic diagram showing recommended survey at sites w~ich are to be opened during winter. 5. If winter active-channel mining is contemplated, an additional site visit should be conducted during winter. This visit is to determine the presence of water at or downstream from the proposed site. 21 I I. SITE PLANNING B. SPECIFIC GUIDELINES Specific site planning should proceed based upon the selected gravel removal method. I. Scraping in Active and Inactive Floodplains: a. Material sites should be mined to ensure that after the rna- terial is removed, sufficient gravel remains to maintain the low-flow channel configuration (refer to Section VI B 2) b. Since it is most efficient to work scraped sites in a dry condition, the average depth of the groundwater table during the desired period of mining and the effective use of river- training structures should be assessed !refer to Appendix C on river-training structures) 2. Pit Excavation in Inactive Floodplains and Terraces: a. Pits should be considered when a large amount of gravel !>50,000 m3 ) is required from a river that does not have large exposed gravel deposits. If scraping is conducted in a situ- ation where more gravel is required than is accessible within the guide I ines for scraping, overmining may result with corres- ponding habitat and channel alterations. In these cases, it is preferable to go to inactive floodplains or terraces and exca- vate a deep pit !refer to Appendix Don pit design). b. Pits should be located in areas where they wi II have a low probabi I ity of diverting channels into the mined area. This means they should be located on terraces, inactive floodplains, or stable islands with the recommended buffer. Terraces are preferred because of the reduced probabi I ity of channel diver- sion. 22 I I. SITE PLANNING c. It is usually desirable to locate the pit within a dominant, homogeneous mature vegetative community. This location wi I I reduce the chance that a terrestrial habitat of I imited avail- ability will be affected and will generally increase habitat diversity. d. It should be decided during site planning whether or not the pit is to be connected to the river following the mining opera- tion • A pit outlet provides an avenue of escape for fish that become trapped in the pit during high water. A connected pit, if properly designed, can provide fish rearing and overwintering and increase the avai labi I ity of sport fish. Conditions necessary to provide suitable fish habitat in- clude a diversity of depths with an average depth that mini- mizes the probabi I ity of winter mortality. • An unconnected pit has the potential to trap fish during high water. If the pit is adequately protected from flooding with a buffer of suitable height, and if the pit is not to be managed for fish the creation of overwintering habitat is not necessary and the average depth is not critical. A diver- sity of water depths is desirable to create adequate water- fowl and shorebird habitat. 3. Dredging in Active Channels of Large and Medium Rivers a. Dredging in active channels of large and medium rivers should be considered only if suitable floodplain sites are unavai 1- able outside the active channel. In this situation, nonflood- plain sources also should be evaluated. b. Sites located in active channels should consider the following: 23 I I. SITE PLANNING i I Essential aquatic habitat in and downstream from the site iiI Unimpeded instream migrations iii I Maintenance of natural pool :riffle ratio; riffles should be avoided except in the following situations: • In a long riffle, excavation may be acceptable near the middle of the riffle • When more rapid site recovery is desirable • When the riffle is unproductive aquatic habitat be- cause of cementation or infiltration by fine"sediments • Where deepening the thalweg may reduce or eliminate aufeis development 24 I I. SITE PLANNING Work Plan Development Section Ill Page Maps, Sketches, Photographs 26 Legal Description 26 Site Description 27 Environmental Description 28 Work Plan Development Section Ill Detailed work plans should be prepared and submitted as part of the appl ica- tion to the appropriate review agency. Work plans should include detailed sketches, ground photographs, topographic maps, and if avai I able, aerial photographs showing: • Accurate site boundaries • Individual sequential work areas and boundaries • Buffer locations and boundaries for both individual work areas and the total site • Locations of alI floodplain temporary and permanent structures planned for site operation and closure !e.g., access roads, river-training struc- tures, bank protection devices, stockpiles, washing and processing struc- tures, and overburden pi lesl • Locations of gravel-use points !such as access roads, airstrips, and camp padsl Visual resource classification maps, if avai I able from State or Federal agen- cies, of the region surrounding the work site, should also be submitted. Spe- cific sections of the work plan should present written descriptions that address the following topics. A. A brief legal project description identifying: I. Names and addresses of applicant and major contractors, if known 26 I I I . WORK PLAN DEVELOPMENT 2. Intended material use, location of material use, and anticipated I ife of the project uti I izing the material 3. Life of the material site 4. Ownership of material site and adjacent lands B. A technical site description identifying: I. Size and specific location of all individual and cumulative work areas 2. Season, duration, and frequency of all site work by individual work area 3. Buffer locations, dimensions, type of vegetation, and soi I description 4. Methods, schedules, and locations for vegetative and overburden clearing, temporary storage and hand I ing, and permanent disposal 5. Quantity, type, and use of material to be removed from each work area 6. Method of gravel removal· in each work area, including type and number of equipment and identification of each material handling step to be performed within the material site I i.e., collection, stockpi I ing, sorting, washing, processing, transporting!. Locations and operation of each hand I ing step should also be identified. Washing operation descriptions should identify si It control proce- dures and processing operations should identify use and storage locations of materials such as solid waste and cement-processing additives. 7. Cross-sectional configuration and location of progressive working elevations by season or major project scheduling periods. For I I I . WORK PLAN DEVELOPMENT 27 example, if the site is to be worked over several years, the de- signed profile and configuration during each spring breakup and low summer flow should be identified. Final working profile and config- uration and site closure profile and configuration should also be identified. 8. Specific locations, specifications, material composition, and con- struction method of access roads, river-training structures, and si It control structures. 9. Site closure lrehabi I itationl methods and procedures including loca- tions and specifications of permanent structures lsuch as overburden pi lesl. At pit sites consideration should be given to whether access should remain after site closure. This decision influences the design I ife of the access road. 10. Descriptions of logistical support and material transportation methods, general routes, and frequency to and from the material site C. An environmental description of the project area identifying: I. Known biological resources of the general vicinity, including fish- ery resources of the subject river system 2. Timing of major fish and wildlife history events and presence of I imiting habitat occurring in the vicinity of the material site 3. Hydraulic characteristics I such as channel configuration and dis- charges) in the vicinity of the material site D. The approved work plan should be considered an integral part of the project by both the permittee and the permitting and monitoring agencies 28 I I I. WORK PLAN DEVELOPMENT Agency Review Section IV Disapproval Basis .•. First Field Inspection Second Field Inspection Third Field Inspection Page 30 31 31 32 Agency Review Section IV A. The proposed material site location and accompanying work plan should be reviewed by appropriate agencies to evaluate the compatibi I ity of the project with the environment. This review should consider disapproval or modification of the work plan if the material site directly affects areas or species of special concern. Examples of such areas or species include: I. Threatened or endangered species and their habitats that are deemed essential to the survival or recovery of these species that are recognized by Federal and State governments. A current I isting of species and information as to their distribution may be obtained from the U.S. Fish and Wildlife Service or the State Fish and Game agency. Sites affecting these species or their habitats may be prohibited, or require substantial justification. 2. Habitats I imiting local populations I such as fish spawning and overwintering habitats, Dal I sheep lambing areas or raptor nesting habitats!. Sites directly affecting these habitats should not be considered further unless alternate sites are not avai I able. 3. Undercut vegetated banks and associated riparian zones 4. Incised vegetated banks and associated riparian zones, except for proper I y uti I i zed access by f iII ramps 5. Springs 30 IV. AGENCY REVIEW 6. Active channels in sma II rivers of meandering, sinuous, and straight configurations 7. Wetlands-The primary criteria most frequently used in wetland definitions include presence of water-saturated soi I conditions, and vegetative communities adapted to such conditions. For current definition, delineation and jurisdiction refer to local offices of the U.S. Army Corps of Engineers. 8. Other Federal, State, and private lands with special use and regula- tion such as wilderness areas, parks, wildlife refuges, archaeolog- ical areas, and historical landmarks B. A field inspection of the proposed site by the appropriate agency should take place prior to site approval. A field inspection as described in Appendix B should occur during an open-water season and include an evalu- ation of: I. Overall technical feasibility of project as detailed in the work plan 2. Overall quality of fish and wildlife habitat to be disturbed 3. Presence of any previously unknown features identified in Section IV-A 4. Hydraulic characteristics such as discharge and stage in the vicin- ity of the material site Alternative sites should be requested of the applicant if it is judged in this review that the material site wi I I alter areas or species of special concern to the point that population survival is affected. C. A second inspection by the appropriate agency should occur during site operation to: 31 IV. AGENCY REVIEW I. Confirm that the work plan is being followed 2. Determine if unexpected biological, hydraulic,. or engineering char- acteristics warrant a deviation from the original work plan D. A third field inspection by the appropriate agency should occur in the latter stages of site closure prior to site abandonment and removal of essential site closure equipment to ensure: I. Final slopes, contours, and configurations of the work area comply with the intent of the work plan 2. All additional site closure work has been performed and the site will be abandoned, within practical limits, as close to original conditions as possible Additional visits after closure may be appropriate I i.e., to monitor erosion centro I I. 32 IV. AGENCY REVIEW Site Preparation Section V Page GENERAL GUIDELINES ••......... 34 Verify Boundaries . . . . • . . . . 34 Access . . . . • • . • . . . . . . 34 Buffers • • . • • . . . . . . . . . 35 Dikes . . . • • . . • . . . . • . . 40 Vegetation Clearing .......• 42 Vegetation/Overburden Hand I ing .. 42 Settling Ponds 44 SPECIFIC GUIDELINES FOR SCRAPED SITES •• 44 A. GENERAL GUIDELINES Site Preparation SectionV I. At sites opened during winter alI work area boundaries estebl ished during the initial site visit !such as active channels, buffer loca- tions, vegetefed areas, gravel deposits) should be verified to avoid accidental damage to active channels, buffer zones, and vegetated banks 2. Design of floodplain access should incorporate the following factors: e. Minimize access through vegetated habitats b. If necessary to traverse vegetated areas: • During winter do not remove the organic layer end do not cover the access route with gravel; use ice roads to avoid compaction of organic layers • During summer do not remove the organic layer, but protect from mechanical ripping and tearing by covering with gravel c. Floodplain access should occur at the inside of e meander to avoid trefficing incised banks at outside meanders d. Avoid crossing other incised floodplain banks e. When a bank crossing is required it should be protected with a gravel fl I I ramp f. Avoid crossing active channels 34 V. SITE PREPARATION g. When required, active channels should be crossed via temporary bridges, low-water crossings, or properly culverted access road. Refer to Appendix Eon fish passage. h. Floodplain travel to and from the work area should occur only on designated access roads 3. Buffers are areas of undisturbed ground surface that are designed~ maintain the integrity of active channels. In general, low-flow or flood-flow buffers are recommended at a site. Low-flow buffers are recommended for scraping operations on unvegetated gravel bars adja- cent to active channels. Flood -flow buffers should be used for scrap- ing or pit-mining operations that are separated from active channels. Operators of gravel removal activities may desire to use buffers wider or higher than those recommended in order to protect the site from inundation while it is being worked, since water levels at the time of mining may exceed those for which the buffer is designed. a. The low-flow buffer is a strip of undisturbed ground surface extending up the bank and beneath the water surface from the low summer flow water's edge !Figure 41. Its purposes are: • To maintain the integrity of the channel configuration and • To minimize change to the aquatic habitat The boundaries of the low-flow buffer are defined as follows !Figure 51: i I The upper I imit at any location along the channel is that point on the bank that is the lesser of the following: • having an elevation that is 0.5 m above the low summer flow water surface elevation 35 V. SITE PREPARATION Figure 4. Schematic diagram of the low-flow buffer. w ---~h~E~~-~~~~~~~-------~-o.sm }sm '4.ow-Flow Buffer o.sw Figure 5. Schematic diagram showing low-flow buffer boundaries. 36 • having a horizontal distance to the low summer flow water's edge which is equal to one-half the channel top width at channel-ful I flow conditions i il The lower I imit at any location along the channel is that point on the bed that has a horizontal distance to the water's edge which is 10 percent of the top width of the low summer flow channel. b. The flood-flow buffer is a zone of usually undisturbed flood- plain, often vegetated, separating the material site from the active channel !sl !Figure 6). lts purpose is to prevent the Figure 6. Schematic diagram of the f load-flow buffer. 37 V. SITE PREPARATION active channel lsi f~om dive~ting th~ough the mate~ial site fo~ a selected pe~iod of time. Although it is p~efe~able to use natu~al vegetated buffe~s, man-made buffe~s in the fo~m of ~ive~ t~aining st~uctu~es and bank p~otection devices lsee Appendix Cl may be necessa~y whe~e natu~al buffe~s do not exist o~ a~e too low to be effective. i I Flood-flow buffe~ design, as discussed in Appendix A, should include conside~ation of: • Buffe~ location with ~espect to the active channel lsi and the mate~ial site • Buffe~ width sufficient to withstand anticipated e~osion without jeopa~dizing the integ~ity of the buffe~ • Buffe~ height sufficient to dive~t floods iiI lmpo~tant va~iables to the selection of buffe~ location, width, and height include: • Channel configu~ation • Rive~ size • Hyd~ology • Active channel alignment • Channel aufeis • Pe~maf~ost o~ ice-~ich banks • Type of vegetation 38 V. SITE PREPARATION • Soi I composition iii I Recommended flood-flow buffer designs are I isted below for scrape and pit gravel removal operations: • Scrape-In these sites, it is recommended that the site be protected from channel diversion by a buffer for at least 5 to 8 years. This allows the vegetation to become re-established. The following Table I ists recommended minimum buffer widths for different river sizes: River size Sma II Medium Large Minimum width lml 15 35 50 -The width can be reduced to half the recommended minimum at the downstream end of the scraped site -The height of the buffer should be at least as high as the water level during a 5-year flood • ~-In these sites, it is recommended that the site be protected from channel diversion by a flood- flow buffer for a period of at least 20 years. This provides a more long-term protection of the newly created habitat. The following Table I ists recommended minimum widths for different river sizes: Minimum width River size lml Sma II 75 Medium 150 Large 250 39 V. SITE PREPARATION -The width can be reduced to 20 percent of the recommended minimum at the downstream end of the pit -The height of the buffer should be at least as high as the water level during a 20-year flood ivl Flood-flow buffers should be designed on a site-specific basis following the guide I ines presented in Appendix A under any of the following conditions: • The material site is on a very large river le.g., Yukon River, Kuskokwim River, Tanana River, and Col vi I le River) • The avai fable space does not allow for a buffer of recommended width • Buffer height is lower than the recommended design height • The active channel is angled into the bank at an angle greater than about 30 degrees • Channel aufeis occurs in the river adjacent to the site • Banks consist of primarily sands, are sparsely vege- tated, or are ice-rich permafrost material • Evidence of active bank erosion is found during the site visit 4. Temporary dikes should be constructed around the site if the site wi I I be inundated during operation !Figure 71. Refer to Appendix C discussing river-training structures. 40 V. SITE PREPARATION a. Very large braided river b. Medium braided river c. Medium split river d. Large meandering river Figure 7. Potential locations of temporary dikes cons t ructed around sites having the potential to flood during site operation . v. SITE PREPARATION 41 a. These structures should be constructed to minimize disturbance to low-flow channels b. Dikes should be constructed of on-site gravel materials c. Fish entrapment should be avoided at alI times 5. In cases where vegetated areas cannot be avoided, clearing should proceed using the following guide I ines: a. If possible, sites co~taining dense vegetative cover should be cleared during periods that do not coincide with periods of bird and mammal breeding, nesting, and rearing-of-young. In most cases fal I would be the most desirable period for vege- tation removal. b. When mature timber must be cut, it should be salvaged for pri- vate or commercial use. If no such use exists, timber should be either: • Stockpiled out of the active floodplain • Used in site rehabi I itation of adjacent material sites • Hauled to designated disposal areas • Pi led and burned in accordance with appropriate regulations 6. Other vegetation and organic overburden can be mechanically cleared and should be collected. This material should be saved for possible use during site closure. At sites located in inactive floodplains or terraces, this material should be broadcast over the surface during site closure. In sites located only in an active floodplain, this material can be pi led I not broadcast) within the site according to the following recommendations. The presence of this material in the materi- 42 V. SITE PREPARATION al site in an acceptable manner wi I I faci I itate more rapid vegetative recovery and subsequent fauna recovery. a. If the site occurs only within an inactive floodplain or terrace in any configuration or size river, the material should be tempo- rarily stored either: • In piles within or on the edge of the material site • In a temporary storage area outside the material site !such as an approved disposal area, material site, or unvegetated inactive floodplain! b. If the site occurs only within an active floodplain, vegetative ~lash and organic overburden should be disposed of based upon river configuration: i I If located in a braided river this material should not be pi led or broadcast in the active floodplain of these systems i il If located in a meandering, sinuous, split, or straight river this material can be handled as follows: • If sufficient space exists away from the active chan- nel, store this material in piles within the material site. On-site storage should occur at a location that reduces repeated hand I ing. During storage the material can be stockpiled in as smal I an area as possible to reduce excessive site enlargement to compensate for covered gravel. These materials should be stockpiled in a location and in such a manner that slope failures and erosion would not endanger the adjacent stream or have other adverse effects. These piles should be: 43 V. SITE PREPARATION -Located away from active channels -Long and narrow -Orientated para I lei to the flow -Of sufficient height to be above the 2-year flood -Armored on the active channel side to prevent erosion Refer to Figure 8. • If insufficient space exists within the mined area away from active channels this material may be stored in: -An approved disposal area -An upland area -Other material sites -Unvegetated inactive floodplains 7. Settling ponds are recommended if the materials are to be washed within the material site. Ponds should be protected with dikes de- signed for the 10-year flood. Ponds generally should be located as far from the active channel as possible. See Appendix F for guide! ines to be considered in the design of settling ponds. B. SPECIFIC GUIDELINES FOR SCRAPED SITES I. Material sites worked during the open-water season should be pro- tected from flows corresponding to at least the 2-year recurrence 44 V. SITE PREPARATION five Channel Terrace ~ ' II Temporary Storage of Overburden '\ /J MinedSite Boundary Channel Figure B. Typical view of temporary storage of overburden showing desirable location, shape, and armor protection. interval flood by dikes designed to withstand such floods without erosion. These dikes should not encroach on the low-flow buffer. The purpose of the dikes is to reduce the probabi I ity that flow wi I I pass through the active site, thus reducing the potential for introducing high concentrations of fine sediments into flows that are incapable of transporting them to normal dispositional areas. 45 V. SITE PREPARATION 2. If an unvegetated site is armored by coarse gravels or cobbles that do not meet project material specifications, they should be stock- pi led, used in a dike, or otherwise saved for dispersal over the site during site closure. 3. If it is necessary to locate a material site in an active side chan- nel, it should first be diked off at the upstream and downstream ends. The dikes should be constructed to a height corresponding to at least the stage of a 5-year flood flowing in only the other chan- nel lsi. The side of the dikes facing the active channel should be protected against erosion during such floods. Floods larger than this may be allowed to overtop the dikes and flow through the material site. Following large floods the downstream dike should be breached to a I I ow fish escapement. 46 V. SITE PREPARATION Site Operation Section VI GENERAL GUIDELINES . SPECIFIC GUIDELINES Site Matrices Spec i a I Instructions Braided Rivers •.. Split Channel Rivers Meandering, Sinuous, and Straight Rivers Scraped Sites Pit-Excavated Sites Dredged Sites Page 48 49 50 57 60 63 65 70 74 A. GENERAL GUIDELINES Site Operation Section VI I. Changing the course of any active channel should be avoided 2. AI I gravel removal operations should be conducted in a clean and efficient environmentally acceptable manner. For example: a. AI I fuels and toxic materials should be stored out of the flood- plain b. Avoid fueling and servicing equipment within the active flood- plain to reduce spi I Is and disposal of materials !e.g., used crankcase oi I and lubricants! c. The by-products from support operations occurring at the material site !such as gray water, domestic sewage and solid waste I should be disposed of in an approved fashion !consult current Federal and State regulations), In general these by-products should not be discarded within the active or inactive floodplains with- out proper treatment. 3. Floodplain access and travel should occur only as designated in the approved work plan 4. Buffer zones should not be disturbed in any manner that would reduce their function. For example: a. Vegetative structure, width, and banks of flood-flow buffers should not be altered b. Heavy equipment should not repeatedly traffic low-flow buffers, or reduce their height or configuration 48 VI. SITE OPERATION 5. The approved work plan should be followed. If unexpected conditions are encountered in the field, operators should: a. Immediately notify the appropriate agency of the encountered situation, and anticipated work deviation b. Proceed in a manner that closely follows this manual unti I the permitting agency responds 6. Gravel washing operations within the floodplain, settling pond use, and washing activities should be conducted per the general recommen- dations provided in Appendix F. In general: a. Where gravel washing operations are required, the wash water should be recycled with no effluent discharge to the active floodplain b. If settling ponds are required, they should be designed to pro- vide adequate retention time for site-specific conditions. The outflow structure should be perched to avoid fish entrapment. c. The use of a flocculant may be necessary to meet the Federal- State effluent standards B. SPECIFIC GUIDELINES Specific guide I ines for site operation have been developed for rivers of different configuration and size, and for different gravel deposit locations in each configuration and size. The proposed site should be closely matched with the following matrix Tables which direct attention to specific guide I ines applying to scraped, pit excavated, and dredged sites. 49 VI. SITE OPERATION This section is organized in four parts, as follows: Guide I i nes Based on River Type I. Use of Guide I ines Matrices Special Instructions Braided Rivers-Matrix I, with general guide I ines statements Split Channel Rivers -Matrix 2, with general guide I ines statements Meandering, Sinuous, and Straight Rivers - Matrix 3, with general 50 50 57 60 guidelines statements 63 Specific Guide- 1 i nes Based on Mining Method [ 2. Scraped Sites 3. Pit Excavated Sites 4. Dredged Sites I. Use of Guide I ines Matrices SPECIAL INSTRUCTIONS River Configuration 65 70 74 Each of the three matrices is designed for a specific river config- uration. The guide I ines for one river configuration are not identical to those for another configuration, thus the user must be careful that the proper matrix for the river in question is being used. The configurations represented by the three matrices are: 50 VI. SITE OPERATION • Braided Rivers !Matrix I I • Split Channel River !Matrix 21 • Meandering, Sinuous, and Straight Rivers !Matrix 31 Braided Rivers. A braided river typically contains two or more inter- connecting channels separated by unvegetated gravel bars or vegetated islands !Figure 9al. Its floodplain is typically wide and sparsely vegetated, and contains numerous high-water channels. Bars separating the channels are usually low, gravel surfaced, and easily eroded. Split Channel Rivers. A split channel river has numerous stable islands which divide the flow into two channels !Figure 9bl. There are usually no more than two channels at a given reach and other reaches are single channel. The banks of the channel lsi are typically vegetated and stable. The split river floodplain is typically narrow relative to the channel width. Meandering, Sinuous, and Straight Rivers. Meandering and sinuous rivers !Figures 9c and 9dl have a single channel that winds back and forth within the floodplain; straight rivers wind less. Very few islands are found in these systems. Point bars and lateral bars are common, with point bars more frequent in meandering rivers and lateral bars in straight rivers. Banks on the outside of a bend in a meandering river are normally unstable whereas the banks of a straight river are relatively stable. The floodplains of mean- dering and sinuous rivers are usually as wide as the meander belt, and there- fore, are narrower for sinuous rivers than for meandering rivers. Floodplains of straight rivers are narrow. Template Preparation Required Data. After the proper matrix has been identified, the template describing the work plan can be prepared. A template can either be prepared by: I I I using the blank template provided in the back of this manual, or 121 aligning a blank sheet of paper under the parameter descriptions of one of the 51 VI. SITE OPERATION b. Split Channel River c. Meandering River d. Sinuous River Figure 9 . Examples of river configurations !straight rivers are similar to sinuous but with a lower sinuosity ratio). 52 VI. SITE OPERATION matrices, drawing I ines on the blank sheet to correspond to those of the heading columns and identifying each parameter in its proper position. An example of a template wi I I be shown later !Figure !2al. To fi I I out the tem- plate the following information is required: $' ~ • The size of the river at which the mining operation wi I I be conducted !smal I, medium, or large! • The site location or locations with respect to floodplain type !active, inactive, terrace! !see Figure 101 Terrace ~ c "' .I:: () Inactive Floodplain VJ Qj c: c "' .I:: () Active VJ Qi c c "' .I:: () Q) > ~ ,...--..., I Floodplain Figure 10. Floodplain location types. I r !Terrace • The type of channel or channels associated with the desired gravel deposit (active, high-water, abandoned! (see Figure I I l • The type of gravel deposits to be mined tsee Figure ! I I I_ a; 3: "' .B! I~ Fi I I ing Out a Template. For each individual template evaluation, only one river size, site location, and associated channel can be used. Any number of deposit types can be used as long as the.y are alI associated with the same floodplain and channel type being considered. 53 VI. SITE OPERATION Outside Meander Inside Meander /---............. Highwater Channet-------1- --------~~---- ~Vegetated Bank \ \ \ 1 Outside \ Meander I J \i.:~H-~Island I ~ I 1 I / ~ / --~-------/ / '/ Inside I \ I I ~egetated \ Meander Fl gure II. Types of deposit I. Place en "X" under the template space which corresponds to the indi- vidual parameter being considered !Figure 12al. 54 VI. SITE OPERATION \.n \.n "' , < -· <»<D -· c _., "' .. 0' -"' .... -<rTl X 0"' ~3 ., <D -., .. "' < 0 .. ~ ::r ~ .... ::r .. () 0 3 ., .. .... .. a. .... .. 3 ., "' .... .. "' 3 "' .... () ::r .. a. .... 0 a. .. .... .. ., 3 ::> .. i3l:!l- '8 ~He !i'~ flllll::r ~~~-· iili~ OE.l> %::::8: n"2. -· ~CD::: a g Ill ~f .. ,. \!1 0\ f ~ -tn '<' 'g., ~: "'"' CD-· :I oa. -o r§ ~ f !IIi ==a ~~ -·3 ~i &~ I! 0' ~ 5ooou. ,.,.,...., '-- MtV6FP /NACTIV£FP T~ AmvsC ~~~ ~c ~!-r&.( =. 11 II"I+H ~:::m ~ ) XXX Large ~·· FP I lilT IT I '"'" """"" /'V4Cf'14 ~p X X lnactove Floodplam 'TU~ X X Terrace Acn~ C X X X Act1veChannol }(~ )(X H1ghwaterChannel ~C AbandonedChannel &o X Xeed ,.,N'f" ~ ')( X Poont Bar /JrrPIN-/JM X M 1/JOIJINNEL X /NSto£ Otns« /.UAND fjmt" )(IX M•dchanneiBar lns•deMeander Outside Meander Vegetated Island Vegetated Bank ~ ~(Do:~...,cnu..ao-• ..., ..... 1~ X X Small -"-f'f"-j-",f"+~ Med1um Large ~ 2 j ~ "" ;q )(IXIXIXIXIXIX ~~~~:.::~,:::;,:,, [~ l(jXI_X_llCjX iTiTiTiTi Terrace g ., Jl :i!j"jx1xjxjxjxj "'"'c"""" n• :::; i X X I X X Highwater Cnannel ~ ~ n Abandoned Channel .:__~ T:x X X Bed J!! "' )( X X PomtBar X X LateraiBar X X MldchanneiBar UrS/fAL /JM Mri1C/IANN€1. /N.,o£ Our.siD6 ISUND Tx X lnsldeMeander ~~ X Outs•de Meander ~ "'""" X Vegetatedlsland X VeQelatedBan~ "; .. "lf''- "" ~ ~ ~~ !(! ~[ 2 =--1£ <' ~ I • ~ "' ~ t~'' ~ ~~ J$:~;> ~~ ~., ;;,~~ (', "'~~~ /L'" < Ill 'll iil '2 iil ~ 3 l n ~ 0\ l ~ v !lW<_ iTiTi Large s.-L ,.,_..., '-- Acn>E FP ~p Acn"'C JI-7UlC A-DC /3tto I+HNT/!!itl( Ur6/fAL/JM M1~1f/1#16L '"'"06 CNrsto6 /SI.-"'""1( ~ "" ~ ~ Actt~eFioodpla•n g~ i-._,8-:;+:'f"H ~n;~:~: Floodplam ~ XI XIX IX ~ ~"""~ Hrghwater Channel ~ ~ n Abandoned Channel .:.__~ Axx XBect 'j-... X X X PomtBar z J!! ----5: l> 0" ~l~ 'f-.... X X X X Lateral Bar "'--' X X X X M•dchannel Bar ~ -·i ;; 0 X X X X X lns•de Meander X X X X X Outside Meander X X X X Vegetated Island IX X VegetatectBank iS"' .... G:IU.Ac.J·...,--:.... ~ " l2i X B 2. When the template is complete, compare the template to the appropriate matrix !Figure 12bl. 3. Follow down the matrix unti I river size, site location, associated channel, and one deposit type are matched !Figure 12cl. Record Comment Number. 4. If more than one deposit has been "X"ed, continue down until another match is found, then record Comment Number !Figure 12dl. 5. After alI deposit types have been matched, read the appropriate guide- 1 ines Commentlsl to determine if and how gravel is avai I able. Specific mining guide I ines are referenced. 6. Repeat steps I to 5 for other combinations of floodplain and channel type. 56 VI. SITE OPERATION \J1 -.J < c.n '"" "' 0 'U "' JJ )> '"" 0 z I BRAIDED RIVERS-MATRIX I River Site Associated size location channel Type of deposit c ·-- c "' Q) -·--c Q) "0 "' 0. c c L L c -"0 -"' c "' L Q) "' 0. 0 Q) .c "' .0 Q) "0 - "0 0 c u .c "0 c U1 0 -c u L -c "' ·-0 -"' L "' Q) "' Q) -.c Q) "0 L .0 c <]) E "0 -<]) u -:o Q) "' c E Q) > Q) c .0 -"' <]) ~ E Q) ·-u Q) 3: 0 "' .c Q) "0 "' -:J Q) > ~ "' > I "0 ~ L u "0 ·-~ -·-0> ·-u L ·-.c c c Q) I ·-U1 Q) "' "0 L ~ "' L ~ 0> "' "0 ~ "0 U1 ~ 0> E Q) "' u c Q) u ·-.0 Q) 0 "' c :J Q) <JJ ::;: _J <( -f-<( I <( ro o._ _J ::;: -0 > X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X aExpanded comments begin on following page. I I I "" c "' .0 I "0 Q) ~ "' ~ Q) ! 0> Q) > Comments a I. Gravel may be avai I able by scraping or dredging. ! 2. Grave I available by scraping. 3. Gravel avai I able by scraping. 4. Genera II y shou I d not be mined. X 5. Banks should not be mined. 6. Gravel available by scraping. 7. Gravel available by scraping. X 8. Gravel available by scraping or pit . mining. Expended Comments for Braided Rivers Comment I. Generally, the bed of en active channel should not be dis- turbed. If bed deposits ere the only evei leble source, the gravel should be taken only under strict work plans end stipulations. • It is recommended that side channel lsi be mined rather then the main channel. Select side channel lsi that carry less then approximately one third of the total flow during the mining period; block off up- stream ends end mine by scraping operations. Refer to Scraping Guide- lines lVI B 21. • If the main channel must be mined, dredging mey be en appropriate method. Refer to Dredging Guidelines lVI B 41. Comment 2. Greve I is evei leble by scraping gravel deposits to neer the low summer flow, maintaining eppropriete buffers, or no lower then the weter level present during the mining operation. Refer to Scraping Guide I ines lVI B 21. Comment 3. Gravel is evei leble by scraping such that the configuration of the channel is not greatly changed end there is not e high probebi lity of channel diversion through the mined eree. Refer to Screping Guide I ines lVI B 21. Comment 4. Vegetated islands ere often e limited hebltet in these systems end should generel ly be excluded from the work plen. Exposed deposits should be considered before vegetated island deposits. If deposits in feasible alter- native locations ere not sufficient, end vegetated islands ere abundant in the particular reech in question, up to about 10 to 20 percent of this hebitet may be removed from about e given 5-km length of the floodplain. Refer to Scraping Guidelines lVI B 21 or Pit Guidelines lVI B 31. Comment 5. Vegeteted river banks of both active end high-water channels should not be disturbed because of biological end hydraulic elteretions. These should be removed from work plans. 56 VI. SITE OPERATION Comment 6. Gravel is available by scraping within the channel, but the general configuration of the channel should be maintained. Refer to Scraping Guide! ines lVI B 21. Comment 7. In these systems it is recommended to scrape exposed deposits in the active floodplain. If sufficient gravel is not avai I able in the pre- ferred deposits, gravel may be avai I able by scraping in these locations, but the general configuration of the channel should be maintained. Refer to Scrap- ing Guide I ines lVI B 21. Comment B. In these systems it is recommended to scrape exposed deposits in the active floodplain. If sufficient gravel is not available in the pre- ferred deposits, gravel is avai I able in these locations by either pit or scrape methods. Generally, pits should only be considered when more than 50,000 m3 are required. Refer to Scraping Guidelines lVI B 21 and Pit Guide- ! ines lVI B 31. 59 VI. SITE OPERATION ON 01 0 < (/l "" rn 0 ~ rn ~ > "" --co E (f) lx lx lx lx lx River size E :::> ~ ·- "0 1.. "' co "" _J X X X X X X X X X X X X X X X X Site Associated location channe I c -c co "' -·--c "' co a. c c -"0 -co c a. 0 "' .c co "0 0 c u .c 0 -c u 0 -co 1.. -.c "' "0 -"' u .... "' > "' co c "' ·-u "' 3: 0 > .... co > I "0 ·-u 1.. ·-.c c .... co 1.. .... "' co u c "' u ·-.0 <( -f-<( I <( X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X SPLIT CHANNEL RIVERS-MATRIX 2 Type of deposit "0 1.. 1.. c co 1.. "' co :<. .0 "' "0 -c "0 c <Jl co 1.. -c co ·-.0 co "' co "' 1.. .0 c "' E "0 "0 co c E "' "' .0 -co "' .... .... co .c "' "0 co co .... 1.. u "0 .... .... c "' I ·-<Jl "' "' "0 .... "0 <Jl .... "' "' "' 0 co c :::> "' "' lil 0.. _J "" -0 > > X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X ~ aExpanded comments begin on following page. Comments a I. Gravel may be avai labiP by scraping or dredging. 2. Gravel available by scraping. 3. Some gravel may be available by scraping or pit. 4. Genera I I y shou I d not be mined. 5. Banks should not be mined. 6. Gravel avai I able by scraping. 7. Should not be mined. 8. Generally avoid, not much available. 9. Gravel avai I able by scrape or pit. 10. Gravel avai I able by scraping. Expanded Comments for Split Rivers Comment I. Generally the bed of an active channel should not be dis- turbed. If bed deposits are the only avai I able source, the gravel should be taken by dredging or scraping under strict work plans and stipulations. • It is recommended that side channel lsi be mined rather than the main channel. If the site contains a side channel that caries less than approximately one third of the total flow during the mining period this channel can be blocked at its upstream end and mined by scraping. Refer to Scraping Guide I ines lVI B 21. • If channels approximating this size are not avai I able then either the side or main channel can be mined using dredging. Refer to Dredging Guide I ines lVI B 41. Comment 2. Gravel is avai I able by scraping deposits to near the low summer flow, maintaining appropriate buffers, or no lower than the water level present during the mining operation. Refer to Scraping Guide! ines lVI B 21. Comment 3. Gravel is avai I able if suitable buffers are maintained to protect against channel diversion. Refer to Scraping Guide! ines lVI B 21, Pit Excavation Guide! ines lVI B 31, and Buffer Recommendations IV A 3 and Appendix AI. Comment 4. Vegetated islands are often a I imited habitat in these systems and often control channel integrity. Exposed deposits should be considered before vegetated island deposits. If deposits in feasible alternative loca- tions are not sufficient, and vegetated islands are abundant in the river system in question, about 10 to 20 percent of this habitat may be removed from about a 5-km reach of floodplain. Refer to Scraping Guidelines lVI B 21 and Pit Guide I ines lVI B 31. Comment 5. Vegetated river banks of both active and high-water channels should not be disturbed because of biological and hydraulic alterations. These areas should be removed from work plans. 61 VI. SITE OPERATION Comment 6. Gravel is avai I able by scraping in the high-water channel, but precautions must be taken to avoid channel diversion. Refer to Scraping Guidelines lVI B 21. Comment 7. Mining is not recommended in or near the active channel of smal I split channel rivers because there Is not much material avai I able. Comment B. There generally is not much material avai I able in these de- posits and they should be avoided. If only a smal I amount 1<10,000 m3 1 of gravel is needed, these deposits may be considered for scraping. Refer to Scraping Guidelines I IV B 21. Comment 9. Gravel is avai I able by either pit or scrape methods. Generally these should be considered for large amounts of gravel that are not present in adequate amounts in exposed deposits. Pits should be considered when more than 50,000 m3 are required. Refer to Scraping Guidelines lVI B 21 and Pit Guidelines lVI B 31. Comment 10. Some gravel is avai I able by scraping, but the general config- uration of the channel should be maintained. Refer to Scraping Guide I ines lVI B 21. 62 VI. SITE OPERATI~ MEANDERING, SINUOUS, AND STRAIGHT RIVERS-MATRIX 3 0\ "' i I --., E If) X X X X X River size E :::1 "' 0"> "0 '-"' ., .. __J X X X X X X X X X X X X X X Site location c ·-c ., ·--., Q. -"0 Q. 0 "0 0 0 - 0 ~ - ~ "' > "' "' ·-u > ~ ., ·-u '-~ ., '-u c "' < -f-- X X X X X X X X X X X X X X X X X X X X Associated channel Type of a; a; c c c '--., c ., "' .s:; ., .0 c u .s:; c u '--., '-., "' .s:; "' "0 '-.0 c u ~ "' ., c ., c .0 -;;; ., "' ;: 0 .s:; > I "0 ~ '-u ·-.s:; c c "' I ~ 0"> "' "0 ~ "0 u ·-.0 "' 0 ., « :r: « co "-__J .. X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X < aExpanded comments beg,in on the following page. Ul _.., rn 0 .., rn ;l) )> _.., 0 z deposit "0 '-c '-"' ., -'£ "' "0 -c "0 c "' ., c ., ·-.0 ., "' "' .. "0 "0 E "' "' "' ~ ~ "' "0 ., ., "0 ·-~ ~ ·-"' "' "' "' ~ 0"> 0"> c :::1 "' "' -0 > > Comments a I. Some gravel may be avai I able by dredging. 2. Gravel avai I able by scraping. X X 3. Some gravel may be available. X 4. Not recommended in these systems. X 5. Banks should not be mined. 6. Gravel avai I able by scraping. X X 7. Should not be mined. X X X 8. Genera I I y avoid, not much available. X X X X 9. Gravel available by pit or scrape. Expanded Comments for Meandering, Sinuous, and Straight Rivers Comment I. Generally the bed of an active channel· should not be dis- turbed. If bed deposits are the only avai I able source, the gravel should be taken by dredging only under strict work plans and stipulations. Refer to Dredging Guidelines lVI B 41. Comment 2. Gravel is avai I able by scraping deposits to near the low summer flow, maintaining appropriate buffers, or no lower than the water level present during the mining operation. Refer to Scraping Guide! ines lVI B 21. Comment 3. Gravel is avai I able if suitable buffers are maintained to protect against channel diversion. Refer to Scraping Guide I ines lVI B 21, Pit Guide I ines lVI B 31, and Buffer Recommendations IV A 3 and Appendix AI. Comment 4. Vegetated islands are rare in these river systems and should not be disturbed. It is recommended they be removed from the work plan. Comment 5. Vegetated river banks of both active and high-water channels should not be disturbed because of biological and hydraulic alterations. These areas should be removed from the work plan. Comment 6. Gravel is avai I able by scraping in the high-water channel, but precautions must be taken to avoid channel diversion. Refer to Scraping Guidelines lVI B 21. Comment 7. Mining in the active or high-water channels of these smal I rivers is not recommended because there is not much material avai I able. Comment B. There generally is not much gravel avai I able in these deposits and they should be avoided. If only a smal I amount 1<10,000 m3 J of gravel is needed, scraping may be considered. Refer to Scraping Guide I ines lVI B-21. Comment 9. Gravel is avai I able by either pit or scrape methods. Generally these areas should be considered for large amounts of gravel that are not 64 VI. SITE OPERATION present in adequate amounts in exposed deposits. Pits should be considered when more than 50,000 m3 are required. Refer to Scraping Guide! ines lVI B 21 and Pit Guide! ines lVI B 31. 2. Specific Guide! ines for Scraped Sites a. Gravel bars adjacent to high-water and abandoned channels can be scraped to a specified level at the edge of the channel and should be sloped toward the channel to provide proper drainage. An average maximum depth should be maintained in the channel to provide for flow containment during periods of low flow within the channel. The average maximum depth at any point along the channel is the distance between the average thalweg profile I ine and the channel-ful I stage at that point !Figure 131 . ..... f!Jannel~r Thalweg Profile Averf!!Je Thalweg Profile Channel Thalweg Cross Section A-A Figure 13. Definition of average maximum depth and channel-ful I width in a channel. Recommended values of maximum depth that should be maintained in the channel are I isted below for three ranges of channel-ful I width. Values of half the recommended depths should be considered minimum depths below which flow containment would be ineffective. 65 VI. SITE OPERATION Braided Configuration Recommended maximum depth lml Chennel-ful I width lml 0 - 5 5 -30 30 or greater High-water channels 0.30 0.50 0.80 Abandoned channels 0.05 0.15 0.50 Split, Meandering, Sinuous, end Streight Configurations Recommended maximum depth lml Channel-full width lml 0 - 5 5 -30 30 or greater High-water channels 0.40 0.60 1.00 Abandoned channels 0.15 0.30 0.60 b. Gravel bars adjacent to active channels can be scraped to a specified minimum level and should be sloped toward the channel to provide proper drainage. The purpose of e minimum level is to minimize hydreul ic change to the active channel at low flows. The recommended minimum level of gravel removal is control led by the highest of the following three levels: 66 VI. SITE OPERATION • The upper level of the low-flow buffer. This is defined in Site Preparation Guide! ines IV A 3al • The level corresponding to 0.15 m above the average water level expected during the gravel removal operation • The level thet wi I I maintain a specified averaye maximum depth in the channel !Figure 131. Recommended values end minimum values of maximum depth thet should be meinteined are I isted below for three channel width ranges et chennel- ful I flow. Values of helf the recommended depths should be considered minimum depths below which hydraulic change is more likely to occur. Braided Configuration Channel-ful I Recommended width maximum depth lml lml 0 - 5 0.30 5 -30 0.50 30 or greeter I .00 Split, Meandering, Sinuous, end Streight Configurations Chennel-ful I Recommended width maximum depth lml lml 0 - 5 0.50 5 -30 I .00 30 or greeter I .30 67 VI. SITE OPERATION c. Scrapi~g In high-water and abandoned channels should follow the alignment of the channel. Gravel removal design depends on several factors listed below: • Side slopes should be steble for expected flow conditions during a 2-year recurrence interval flood. This wil I reduce the potential for rapid channel shifting. • Channel-ful I top width should not be increased if it can be avoided. If additional material Is needed that cannot be obtained from other dry channels or unvegetated bars, the channel being worked cen be widened to e width no greater than thet of the active channel and preferably half that of the ective channel (especially on meandering, sinuous, end straight rivers!. • Longitudinal channel slope into the materiel site should not exceed 10 times the average slope of the channel (Figure 141. This wi I I minimize the potential for extensive upstream bed degradation. The upstream end of the section of increased slope should be a sufficient distance from the nearest active channel to minimize the potential for channel diversion. Top of Ad;acent Bar or Figure 14. Sketch of high-water or abandoned channe I I ong i tud ina I profile showing recommended channel bed slopes resulting from 'scrap- ing the channel bed. 68 VI. SITE OPERATION • Longitudinal channel slope out of the materiel site et the downstream end should not be adverse (bed elevation in- creasing in the downstream direction). Adverse slopes cause ponding end potential fish entrapment. Maintaining e positive slope (bed elevation decreasing in the downstreem direction) Is recommended to el low for channel drelnege during e flood recession. The downstream end of the disturbance should be separated from the nearest active channel by et least the width of the low-flow buffer for thet channel !Figure 141. d. Scraping in active side channels thet have been diked end de- watered should follow the alignment of the channel end should stey between the low-flow buffers. Gravel removal design depends on other related factors listed below. • Side slopes should be stable for expected flow conditions during e 5-yeer recurrence interval flood. This wil I minimize the potential for slope fei lure end subsequent deterioration of the low-flow buffer. • The width of excavation is limited by the limits of the low-flow buffers !Figure 151. The bottom width Is limited only by the equipment used. Low Summer Flow Stage Excavation Width Stable Side Slopes ·--v~J Figure 15. Sketch of active side channel cross section defining excavation I imitations. 69 VI. SITE OPERATION • Ch8nnel slope into and out of the m8teri81 site should be st8ble under alI flow conditions up to 8nd including 8 5-ye8r flood. This wi I I minimize the potential for bed degradation. • The existing pool-riffle sequence should be retained during the gravel remov81 operation. If it is disturbed, a simil8r sequence should be restored following the operation. • Active ch8nnels scheduled for winter scraping should be evaluated for the presence of flowing w8ter in and downstream from the site; if water is present, the site should not be mined. e. Mining of high-water or abandoned channel bed 8nd 8Ssociated bars should follow Guidelines VI B 2c and VI B 28, in that order, if sufficient gr8vel quantities 8re not avai I able from only one of these sources. If sufficient gr8vel qu8nt it ies are st iII not av8i lable and channels are not 8bundant, or if high-water or 8bandoned ch8nnels are not 8V8i I able, it m8y be necessary to form new wei 1-define~ channels following Guide I ine VI B 2c. High-water channels formed during the gravel mining operation should h8ve an alignment similar to that of n8tur81 high-water channels or the active channellsl of the river. 3. Specific Guidelines for Pit-Excavated Sites A profile 8nd configuration of the work area should be m8intained to pro vi de: a. A minimum surface area of 2.0 h8. Inundated pits sm81 ler th8n this size 8re generally not he8vi ly uti I ized by w8terfowl. I I the pit is connected to the river, a mean depth of 2.5 m or greater should be provided to insure winter surviv81 of fish. 70 VI. SITE OPERATION b. A relatively long and narrow shape aligned longitudinally in the floodplain and providing an irregular configuration with islands and peninsulas is preferable !Figure 16a and 16bl • Islands and low peninsulas provide more diverse shore I ine and aquatic habitats • If the river does divert through the pit, it will have an alignment to follow and wi I I more quickly develop into a channel configuration c. An outlet channel for a path of low resistance when the pit is inundated, reducing erosion of undisturbed terrestrial habitat. An outlet channel also provides an avenue of escape for fish which may become trapped during high flows. • Outlet channels should be deep enough to allow fish passage during low flow conditions and be as narrow as possible • AI I outlet channels should be on the downstream end of the pit to prevent premature degradation of the stream channel and pit • Outlet channels should be connected to a non-depositional area of an active channel and be angled downstream • Outlet channels should not be of straight I ine configuration • Outlet channels should be constructed at the end of the site closure to minimize si I tat ion in the river d. A diversity of water depths and bank slope • At least 30 to 50 percent of the shore I ine should have a gradual slope to provide areas for emergent aquatic vegeta- 71 VI. SITE OPERATION a. Aerial view of an acceptable pit configuration. Marsh/ Littoral Area\ LowlandZ b. Side view of an acceptable depth regime (Section A -A). Figure 16. Example of a preferred shape and depth profile of gravel pits in. floodplain terraces and connected to the active channel. 72 VI. SITE OPERATION tion, shorebird and waterfowl feeding, juvenile fish rearing, and muskrat habitat !Figure 16bl. The gradual slope of these areas should allow a natural transition of vegetative com- munities and provide exposed mud flats or the potential for future marsh habitat development. • The remaining shore I ine should be more steeply sloped to provide habitat more beneficial to other groups such as diving ducks, geese, swans, beaver, and adult fish • As mentioned above, a mean depth of 2.5 m or greater of combined I ittoral and deep areas should be provided if there is an outlet channel or if a non-connected pit is to be managed for fish. For example, 25 percent littoral area averaging 0.5 m and 75 percent deep area averaging 3.2 m yields an overal I mean depth of 2.5 m. Refer to the Pit Design Appendix D. • In a pit not connected to the active channel, and not to be managed for fish, a similar shape and depth configuration is appropriate, but a mean depth of 2.5 m is not required. These pits should be protected with an adequate buffer from flood- ing so that fish entrapment is minimized. In this case, the main purpose is the creation of shorebird and waterfowl habitat. • If there is a choice between mining to a shallow depth over a broad surface area or deep over a restricted surface area, the choice should be to increase depth before increasing area. This minimizes terrestrial disturbance and reduces the probability of fish winter mortality. 73 VI. SITE OPERATION 4. Specific Guidelines for Dredged Sites a. Active channels scheduled for winter dredging should be evaluated for the presence of flowing water in and downstream from the site; if water is found, the site should not be mined b. Depth of excavation in en active channel should be limited by the width of the low summer flow channel minus the low-flow buf- fer; the side slopes should be designed to remain stable during 5-yeer flood flows c. The length of excavation in e pool of the active main channel should not exceed the length of the pool. If a riffle is to be mined, the length of excavation should not exceed the average length of the pools within 5 km up en~ tiownstream of the site. d. The bed slopes et the upstream end downstream ends of the active channel excavation should be designed to remain stable during 5-year flood flows to minimize the potential for degradation 74 VI. SITE OPERATION Site Closure Section VII GENERAL GUIDELINES • SPECIFIC GUIDELINES Scraped Sites Pit-Excavated Sites Dredged Sites Page 76 80 80 80 81 A. GENERAL GUIDELINES Site Closure Section VII After mining is completed, material sites should be rehabi I itated to return them, as closely as is possible, to pre-mining condition. I. The site should be sloped and contoured immediately following comple- tion of operations. In cases where sites consist of two or more al iquots, each should be sloped and contoured as completed. Any seeding and ferti I izing should be done in spring or summer. 2. The work area should be shaped and contoured to minimize pending and to blend with surrounding features and topography 3. Access roads, culverts, and bridges should be removed !unless other- wise approved! and the areas restored. Fi I I ramps at incised banks should also be removed and the bank stabilized I if damaged! to minimize subsequent erosion. 4. AI I manmade debris should be removed from the site 5. AI I cut slopes encountered during gravel removal or access road construction should be stabilized to prevent thermal, fluvial, and wind erosion 6. Dewater settling ponds of the clear surface water either by pumping or lowering dikes. Silt may be: • Left in place in inactive floodplains and terrace locations; protective structures should be lowered to a level corresponding to the level of the impounded si It 76 VI I. SITE CLOSURE • Broadcast or pi led with other overburden and vegetative slash and debris !refer to guideline VI I A 71 • Removed from active floodplain sites to approved disposal areas 7. In general, at sites that were previously vegetated and wi I I contain nonflooded areas following site operation, rehabilitation should feci litate natural revegetation and site recovery. When organic overburden and vegetative slash and debris are avei I able, it is recommended that natural revegetation be favored over artificial seeding and ferti I ization. Final placement of overburden and vege- tative slash end debris should incorporate the following guidelines. e. Active floodplains i I In braided systems it is unlikely that any overburden or vegetative slash and debris wi I I be avai I able. However, if avai I able it should not be pi led within the active flood- plain. iil In meandering, sinuous, split, and straight systems this material may be pi led within the active floodplain. The design and I oct ion of these piles should incorporate the following !Figure 171. They should be: • Located away from active channels and in areas where they are subjected to the least hydraulic erosion • Long and narrow in configuration !about 15-20 m long and 3-5m wide, where possible! • Orientated para I lei to the flow • About I m above the 2-year recurrence flood at its top 77 VI I. SITE CLOSURE Temporary Pile Shape. During Operation (Refer to Fig. B) Pile at Closu 3-Sm Wide Figure 17. Typical view of desirable shape end configuration, relative to 2-yeer flood levels, of permanently pieced overburden piles. • Armored.on the active side to prevent erosion !refer to discussions of bank protection in Appendix Cl • PI led to maximize surface area, provided this meets the above criteria If sufficient materiel exists, it Is desirable to produce several piles distributed throughout the mined area. If insufficient materiel exists to meet the above cri- teria, it should not be pi led within the active flood- 78 VI I. SITE CLOSURE plain. If insufficient space exists within the mined area away from the active channel, this materiel may be used either in site rehabilitation of adjacent materiel sites or disposed of in approved upland areas. ii il Neither artificial seeding nor ferti lizetion should be conducted in active floodplains b. Inactive floodplains and terraces At these locations in rivers of alI configurations this ma- terial may be either pi led or broadcast over the ground surface i l At sites consisting only of inactive floodplains that are annually flooded it may be best to pile this ma- terial rather than broadcast it to reduce downstream transport. If pi led, the guide I ines presented above 17al should be followed. ii l At sites including terraces and inactive floodplains that are not annually flooded, this material should be broadcast throughout these portions of the mined site. In general, this material should be spread about 10 em deep and should cover as large an area as pos- sible. iii l If this material is not avai table for use in site reha- bilitation of terraces and inactive floodplains, arti- ficial seeding and fertilization may be considered and should follow current state-of-the-art techniques for arctic and subarctic regions 79 VI I. SITE CLOSURE B. SPECIFIC GUIDELINES I. Specific Guidelines for Scraped Sites 8. Distribute coarse gravels or cobbles, when available, over the surf8ce of the gr8vel removal area, to provide for a more r8pid re8rmoring of the surf8ce b. If the low-flow buffer was disturbed, return it to its natural configur8tion and height c. At side channel sites which were diked to work in a dry con- dition, remove the downstream dike and lower the upstream dike to a level corresponding to the river stage of a 1.25-year flood. Tbis wi I I prevent large quantities of sediment from being washed from the site into the river 8t low-flow conditions. 2. Specific Guidelines for Pit Excav8ted Sites a. Overburden and vegetated slash and debris should be: • Broadc8st or pi led, or both, in the nonflooded portions of the mine site, including islands and shore I ines • If any materi81 remains, some may be pl8ced in the flooded portion of the site to provide nutrients and cover b. Slope and contour shoreline b8nks and alI overburden stockpiles in nonflooded portions of the mined area to provide naturally appe8ring configurations th8t blend with surrounding features. These procedures should provide and maintain those characteris- tics of diverse shore! ine configurations and profile, bank slope, and water depth as discussed in previous operation guide I ines. 80 VI I. SITE CLOSURE c. Excess unused mined material should be used to form islands or vary water depths within the pit d. Follow work plan regarding access to the pit e. The outlet channel, if provided in work plan, should be con- structed during the final phases of site closure. Refer to Opera- tions Guide! ines for design criteria !Section VI B 3cl. 3. Specific Guide I ines for Dredged Sites If the low-flow buffer was disturbed, return it to its natural config- uration and height 81 VI I. SITE CLOSURE SEK)!pueddy Appendix Pege A. FLOOD-FLOW BUFFER DESIGN • 84 B. FIELD INSPECTION: Desirable Dete, Procedures end Equipment • • • • • • • • • . . . • • 107 C. RIVER-TRAINING STRUCTURES AND BANK PROTECTION DEVICES • • • • • • • • . . . I 17 D. DESIGN OF PITS • • • • • • • • • • • • • 127 E. FISH PASSAGE STRUCTURES • • • • • • • • 131 F. SETTLING PONDS AND WASTEWATER TREATMENT • • • • • • . . • • • • • • • 135 G. EFFECTS OF BLASTING ON AQUATIC ORGANISMS • • • • • • . . • • • • • • • I 39 H. STANDARD FORMULA AND CONVERSION FACTORS • • • • • • • . • • . • • • • • 145 I • GLOSSARY • • • • • • • • • . • • . • • • 157 APPENDIX A FLOOD-FLOW BUFFER DESIGN INTRODUCTION Flood-flow buffers should be designed to prevent the diversion of en active channel through the materiel site. The design life is usually some finite period ranging from 5 years for some scraped sites to possibly 50 years or more for some pit sites. The reco11111ended design procedure is to c·onsider the lateral activity of the particular river based on its channel configuration end historical migration pattern. The river size, soi I composition of the buffer materiel, vegetative cover, permafrost ~enks, and channel aufeis are also important considerations affecting the stebi I ity of the buffer. The hydrology of the river must be considered to evaluate the frequency that the buffer wi I I be flooded. Each of these are discussed in more detai I in the following sections. BUFFER WIDTH Lateral Channel Migration The general procedure for estimating the amount of channel migration of e river is summarized in this section. The user is referred to Brice I 1971 l for a more detailed explanation of the procedure. Stereoplotters, when avai 1- eble, are e fester and more accurate means of estimating lateral migration. Additional information on stereoplotter use can be obtained from photogrem- metry textbooks, photogremmetric consultants, or stereoplotter manufacturers' I i terature. Because of the complexities of the bank erosion process, quantifying lateral migration usuel ly involves the use of historical records. These ere projected based on e knowledge of the chennel configuration and other con- siderations discussed later. Aerial photographs are obtained of the reach of 84 river being studied !generally at least two floodplain widths upstream end downstream from the mined site locetionl. Photographic coverage is desired for as many years as ere evai I able, but should at least include photos 20 or more years epert for the evaluation of long-term changes. The photos can be repro- duced to obtain slides as described by Brice I 19711 or can be used in print form as described below: I. Enlarge the photos to the same scale, whenever possible. Select three or more identifiable features on each photo. Piece en overlay over one photo end mark the selected features on the overlay. Piece the overlay over the other photolsl and match the features to these marks to verify that the scale is the same. If the scales are identical, the river banks can be traced from each photo on the same overlay !Figure A-1 1. The lateral migration can be measured directly from the over ley. If the scales ere not the same, the follow- ing steps ere necessary. 2. Select two identifiable features on each of the photos end connect these to forme baseline !Figure A-21. These features should be located near the opposite ends of the photograph. 3. Subdivide the baseline into 10 or more segments end drew lines perpen- dicular to the baseline through each of the segment endpoints, extending the I ine through the eree for which the lateral migration estimates are de- sired. Subdivide one of these I ines end drew lines perpendicular to form a grid pattern !Figure A-31. 4. Prepare a similar grid to any desired scale on e sheet of paper. Transfer bank locations at each grid square boundary from each photo to the corresponding grid square boundary on the sheet of paper !Figure A-41. The rows and columns can be numbered end/or lettered to assist in the coordination of the transfer. 5. Connect the points on the paper to show the bank positions as they appear on the photos !Figure A-51. The smeller the grid is on· the photos, the more accurate the bank lines wi I I be. Lateral migration can be measured directly from this figure. 85 p-Lake 1978 \_Bedroc~ CAll crop Irregularly Shaped Grove of Trees-- Figure A-1. Schematic of overlay showing topographic features used as match points and bank I ines from 1948 and 1978 photographs. Figure A-2 •. Schematic showing the selection of features to use as baseline endpoint for a portion of the study reach. 86 r ~r ~IL l\ 1\ 1' I LB.!! SEliN n ~ \ \ I 1-Grid t2 (~ I\ l ; /LB.!! SF 1~1 :-ll \ ~ " ~ \ I v 1/ T / l...,d 'I 1950 v .11 /1 / m5 Figure A-3. Schematic showing the development of a grid on each photo. The accuracy of this technique is sufficient for estimating the expected life of the buffer zone or, conversely, the required width of the buffer to meet the design life expectations. The accuracy of the average annual migration is greater for longer time periods between photo dates. Brice I 1971 l notes that the accuracy depends on the original scale and definition of the photos, the scale of the enlargement, the degree of scale distortion in ·the photo, the numbers and reliability of features used as reference points, end the cere used in matching. It is generally not advisable to use the edge of lakes or rivers as reference match points or as bank lines for migration estimates because of the veriebi I ity of this feature with water level changes. Channel Configuration Channel configuration is en important parameter in evaluating the poten- tial for extending pest records into the future. Each configuration Is dis- cussed separately in the following sections. The effects of buffer height ere discussed in a different section. Braided Configuration. Braided river channels ere often very active laterally within the active floodplain. When a major active channel Is flowing along e vegetated cut bank, substantial bank erosion can take place. If the major channel was flowing along the bank during the entire period over which 87 c~ /r ahB1CrD1E FG~I J I'A.'Brr.1~ E,F,~ V4[L 1\ \ 7' Qiv \ / ~I RJk~ lr"lc. ~ 1le.tlsl"11r ~ f); "'<: 2 \ \ 2 II ~ "' 3 J 3 fl !I\ 4 1/ Grid 1'1 v 'I IX rT Is _.......... 7 IS / 1/ 7 rz 16 / v v 6 IT; 117 L'f' / 171/ / 17 f// / llj \ 1950 I I /;_ 'l /' 1975 \ E ~g 1\B c D J 0 ~A\E INE 1/; ;f/ r; 1 \ \ r-{ 1/ 1/; ! 2 1\ \ -l D ~ 7 Ill 3 \ ~ ~r< r; 4 1\ \ \ GD 5 \ 6 \ \ 7 ( D <.. :J \..[) - Figure A-4. Schematic showing the transfer of the bank I ines from the photos to the paper grid. 88 A B c H J 'V' I'~~ I I J 1 D~,l:'-'"r 1 =Kr 7, ~·x: DepOsition Erosion-1 ~ I I 1 'Ill ' Y' 1 ..... -2 r · ~ I I Figu~e A-5. Completed schematic showing bank I ines and zones of e~osion and deposition f~om which ~ates of e~osion can be measu~ed. .rosion the historical mig~ation ~ates we~e estimated, that migration rate may be projected into the future. Otherwise, different locations on the floodplains should be selected for obtaining estimates. Any change in the alignment of the channel should be accounted for, with erosion rates Increasing for increasing angles of the channel to the bank. A factor of safety should be applied to the result, its value depending on the confidence one has in the estimate for a given system. As a hypothetical example, consider the length of bank labeled A In Figure A-6. The dashed line shows the channel as it appeared In 1950 and the sol ld line represents the location of the 1975 river channel. Assume that the lateral migration of bank A was measured to be 100m, or 4 m per year. Assume it is desired to have a buffer lasting at least 8 years to protect a scraped gravel removal area in the inactive floodplain. Projecting the past into the future results in 4 m per year for 8 years, or 32m. 89 Figure A-6. Schematic of a river with a braided configuration with the 1950 and 1975 channel locations shown. • The 1950 channel alignment was at a larger angle to the bank than the 1975 channel; thus it Is likely that the erosion rates were greater than 4 m per year for the 1950 alignment and less than 4 m per year for the 1975 alignment. The 32m can thus be reduced slightly, possibly to 28m. If intermediate photos (between 1950 and 1975) ere evai I able, this figure can be substantiated by estimating the erosion rete for the more recent time period. If the year to year activity of the active channels is relatively low, it can be assumed that the potential for a significant change in alignment is low, end e fairly low safety factor can be used. In this case, e safety factor of 1.5 applied to .the 28m value would result in a buffer width of 42 m. • If the active channels ere known to change substantially every year, the reduction for el ignment should not be appl led and a safety factor 90 of 2.0 or more could be used. This would result in e buffer width of 32 m x 2.0, or 64 m. It is possible to find e braided configuration where the length of benk defining the buffer is not adjacent to en active channel, e.g., area B in Figure A-6. In this situation, the migration rate at area A can be applied to area Band modified for various considerations. Assuming an B-year I ife is desired, the starting width is 32 m. This width can probably be reduced, the amount of reduction depending on the annual lateral activity level of the active channels. Assume that the activity level is low. One might reduce the number to 24m in that situation. However, if the active channel does shift, it wi I I I ikely impinge on the bank at a relatively large angle, increasing erosion potential. As a result, the width should be increased to 36m instead of decreased to 24m. With relatively stable channels, the safety factor can be about 1.5 to obtain a 54-m wide buffer. Split Configuration. Rivers with split channel configurations are typ- ically much more laterally stable than braided rivers. Thus, a historical record of erosion rates for e split river is fairly rei iable for projecting future erosion rates. Channel alignment with respect to the buffer bank is an important consideration, with larger erosion rates expected from channels with larger angles to the bank. The factor of safety to apply to buffers on rivers with split configurations mey be as low as 1.2; the factor of safety would increase with increasing channel activity and with decreasing confidence in the buffer width estimate. See discussions of meandering and braided config- urations for hypothetical examples of extending historical erosion rates. Meandering Configuration. Rivers with meandering configurations typically experience varying degrees of lateral migration, but the location end direc- tion of migration is fairly predictable. A historical record of erosion rates for a meandering system can be used to predict future erosion rates with a high degree of rei iabi I ity relative to previous configurations. Channel align- ment with respect to en eroding benk tends to remain constant. The factor of safety to apply to the width of buffers on rivers with meandering configura- 91 tions may be as low as 1.2 with a good data base; higher values should be used as uncertainty increases In estimating the erosion rate. The pattern of a meandering river and the expected zones of erosion are i I lustrated in Figure A-7. Most meandering rivers deviate to some degree from I I I II I \ I ',,_____ Er, -.... os;o, ---..... ' ' ' \ Meander Belt Width \ Figure A-7. Schematic of a meandering river showing the expected zones of erosion as the river meanders migrate down the val ley. 92 this pattern, but the besic principles ere the seme. Meandering rivers exhibit e general tendency to migretq downvel ley by eroding the cut benk on the out- side of e bend from e point roughly midwey through the bend end extending generel ly to the beginning of the inside of the next bend downstream. The greduel downvel ley progression of the bends usuel ly remains within e zone eel led the meander belt drewn neer the outside of eech meander. The width of the meander belt is usuel ly constant for regul.er meander patterns. Irregular meander patterns do not necessarily meintein e constant meander belt width, but the erosion et the outside of bends is typical. The difference between e regular meander pattern end en irregular meander pattern end the expected zones of erosion essocieted with eech is shown in Figure A-8. It is epperent Regular Meander Pattern Irregular Meander Pattern I Figure A-8. Schematics of regular and irregular meander patterns and typical erosion zones. 93 from the location of the typical zones of erosion that. the buffer width should generally be greater on the outsides of meanders and the upstream side of the insides of meanders. As an example, consider the hypothetical river in Figure A-9 with a regular meander pattern. A material site is proposed on an inside meander of a smal I river, for which a buffer design I ife of 25 years is desired. Figure A-9. Schematic of a river with a regular meander pattern and a proposed location for a material site. The buffer surrounding the material site is separated into zones A and B because they are zones of different expected erosion rates. Historical erosion rates for zone A were 90 m between 1948 and 1978, or an average rate of 3 m per year. In zone B, 270m of deposition has taken place during the same period. Starting with zone B, the bank opposite this zone should be inves- tigated for any abnormality such as near-surface bedrock, which may stop the 94 erosion of this bank. If there is such an abnormality, the buffer width should be increased from the standard minimum buffer width for the downstream end of the site given in Section V A 3b. In this example, assume no abnormality exists; use a standard minimum buffer width increased by 25 percent t.o account for the increased design life 125 years instead of 20 years! to derive a 19m width in zone B. For zone A, an annual migration of 3m per year over 25 years would prescribe a 75-m wide buffer. No change in the average erosion rete is expected from, for example, a meander cutoff developing upstream, end the historical period is longer than the design life, thus, the user can feel confident with the prediction. A safety factor of 1.2 can be used resulting in a recommended buffer width of 90 m. Sinuous Configuration. A river with a sinuous channel configuration is expected to behave in a simi tar manner to that of the meandering rivers with a few exceptions: erosion rates ere often less in sinuous rivers then in mean- dering rivers; and the erosion zone may extend farther upstream on the outside of a sinuous river meander !Figure A-101. Otherwise, simi tar procedures can be used to estimate the recommended buffer zones. Safety factors as low as 1.2 can be applied to the buffers in zones of erosion on these relatively stable rivers. See the discussion on meandering rivers for a hypothetical example of estimating buffer sizes. Straight Configuration. A river with a straight configuration wi I I I ikely have a simi ler erosion pattern to that of sl~uous rivers, only less pro- nounced. Straight rivers typically exhibit a sinuous pattern in their thalweg with the inside meanders being formed by alternate bars or side channel bars. Thus, what little bank erosion takes place in a straight river would occur opposite and slightly downstream from these gravel bars, which may be sub- merged under most flow conditions !Figure A-1 II. Safety factors as low as 1.0 may be appropriate on straight rivers. The reason for the straight el ignment should be considered before evaluating the buffer requirements. For example, if the straight reach resulted from meander cutoffs, a much larger buffer would be required then if the straight reach is due to erosion resistant banks. 95 Figure A-10. Schematic of a sinuous river showing typical erosion zones. Other Buffer Width Factors River Size. In general, erosion rates Increase with Increasing river size. This Increase is prlmeri ly due to the greeter discharges associated with larger river size. The Increase is also due to the wider vel ley floors fl I led with greeter quantities of generally smeller sized el luvlel sediments. The rete of Increase of erosion rates with river size Is difficult to quantify. If historical rates of lateral migration ere evei I able, river size does not have to be considered separately. Sol I Composition. The soil composition of the bank end buffer materiel Is Important to the erosion rete. Fine sends ere generally the easiest to erode. 96 I I I I Potential f Erosjon 1 Zone----;- ' I I I I \ '!\ 'oaa, ~000\ I i1 I I \ I \ \ Thalwe.g \ I I I I '~otential ~~~-r·~ :o0o~ \Erosion Alte ·~:· .. , o o 0 ol Bar g:·g~, ~ ' ' 0 0 ., I 'ooo~ / )1 I ~· I ~ , , Figure A-1 I. Schematic of a straight river showing zones of potential erosion. Larger sized granular material <such as coarse sands, gravels, cobbles! re- quire higher velocities to be eroded because of the increased weight of the particles. With vertical cut banks, large diameter materials often build up at the base of the bank. This build up is because the finer materials holding them in place are eroded away while the larger sized materials cannot be transported. Materiel finer then fine sends lsi Its end cleysl ere often more resistent because of the cohesion between particles. If the buffer materiel is uniform throughout, then historical erosion rates do not need to be modified for soil composition effects. If there ere areas of significantly finer or coarser sized materials, the historical ero- sion rete should be modified accordingly based on the discussion In the pre- ceeding paragraph. 97 Vegetative Cover. Vegetation with deep root structures provides a resis- tance to bank erosion. Dense ground cover on the buffer provides an increase in the roughness of the buffer, causing a decrease in the velocity of flow over the buffer. This, in turn, reduces the potential for erosion of the buffer surface and the development of a channel through the buffer. This is a primary reason why a buffer should not be disturbed. When extending historical erosion rates, the vegetative pattern should be considered. No compensation for vegetation is required if the vegetation is comparable between the buffer and the area that eroded during the period of historical erosion. If the vegetation type or density changes within the buffer, or between the buffer and the area of historical erosion, then the historical rate of erosion should be modified according to the type of change and the discussion in the preceeding paragraph. Permafrost Banks. The erosion of permafrost banks is a more complicated process then unfrozen bank erosion. Varf~us investigators have studied the process; some have concluded that permafrost increases bank erosion, others have decided that permafrost decreases bank erosion. Scott I 197Bl reviewed previous investigations and added his own investigation of five rivers in arctic Alaska. He concluded that the net effect of permafrost is to create greater channel stability than is found in rivers of similar size in nonperma- frost environments. However, banks which are ice-rich wi I I I ikely have less stabi I ity and higher erosion rates than other permafrost or nonpermafrost banks. When using past records to predict future conditions, the thermal con- dition of the banks should be considered. Past thermal conditions of the banks are generally not known, consequently, it must be assumed that they were similar to the current condition. If the banks are ice-rich, the safety factor applied to the buffer width should be larger. Channel Aufeis. Aufeis development in the active channel of a river can cause a larger percentage of the snowmelt runoff to flow across the buffer than otherwise would be expected. Doyle and Childers I 19761 show a photograph 98 of this occurring at the Prospect Creek material site near the Trans-Alaska Pipe! ine. This increased flow can cause erosion of the surface of the buffer, especially any disturbed area. It can also cause scour or headcutting in the material site because of the larger-than-design flows during breakup. The safety factor applied to buffer width should be increased if channel eufeis is known to develop at the site. BUFFER HEIGHT Buffer height and buffer width are interrelated to a certain degree. If the buffer is high enough to keep alI but the largest of floods out of the material site, only bank erosion needs to be considered in buffer design. This may be the situation for many material sites located on terraces. If the buffer is low and is flooded frequently by larger flows, erosion of the sur- face of the buffer, headward erosion of the upstream face of the material site, and scour within the site must be considered in the buffer design. The height of natural buffers is fixed at the level provided by nature. Design options include increasing buffer width to account for low height, bui I ding up the buffer height by adding a dike on the river side, or bui !ding a completely separate buffer structure. These options are discussed in more detai I in a subsequent paragraph. To evaluate the frequency of flooding, hydrologic and hydraulic analyses must be carried out. The detai Is of these analyses are too complex to explain here, but appropriate references are given to allow the user to study the subject further. • A hydraulic analysis is required to evaluate what discharge wi I I ini- tiate overtopping of the buffer. Cross sections of the river, extending up to the level of the buffer on both banks, are necessary for this analysis. It is preferable to have five or more cross sections through the reach of river adjacent to the buffer. The Manning equation or, perferably, a backwater program, should be used to calculate the dis- charge corresponding to the stage that would overtop the buffer. Discus- sions of these analyses are provided in most open-channel hydraulics 99 textbooks !Chow 19591, and in other references !Bovee and Mi lhous 1978; u. S. Army Corps of Engineers 19761. • A flood frequency analysis provides an estimate of the recurrence interval or probabi I ity of exceedance of the discharge which just overtops the buffer. Detailed discussion of flood frequency analyses are included in most hydrology textbooks, U. S. Water Resources Counci I I 19771, and Lamke I 19791. Lamke I 19791 provides equations for deter- mining flood discharges for rivers in Alaska for the following recur- rence intervals and corresponding exceedance probabi I ities: Recurrence interval I years I 1.25 2 5 10 25 50 100 Exceedance probabi I ity 1%1 80 50 20 10 4 2 With the discharge and its frequency of occurrence known, the probabi I ity of that flood occurring over the design I ife of the buffer is needed. Table A-I below provides the probabi I ity of occurrence of a flood of a specified recurrence interval during a specified buffer design I ife. 100 Table A-1. Probability of Occurrencea .1%1 of a Specified Flood During a Specified Design Life Flood Buffer design life I years I Recurrence Exceedance interval probab iIi ty I years I 1%1 2 5 B 10 20 25 50 100 1.25 BO 96 99+ 99+ 99+ 99+ 99+ 99+ 99+ 2 50 75 97 99+ 99+ 99+ 99+ 99+ 99+ 5 20 36 67 63 69 99 99+ 99+ 99+ 10 10 19 41 57 65 BB 93 99 99+ 25 4 B IB 26 34 56 64 67 98 50 2 4 10 15 IB 33 40 64 67 100 I 2 5 B 10 IB 22 39 63 8 Probability of Occurrence I -(I -Exceedance Probabil ityiDesign Life With the known probability of flow through the site during the design I ife of the buffer, the user can evaluate the consequences. If the probability is low, the width of the buffer can be designed based on lateral migration alone. If the probability is high, one of several design options are recom- mended. • If the buffer is heavily vegetated, and if flow through the material site is acceptable, riprap the upstream edge of the material site to prevent headward erosion; or, increase the width of the buffer to allow for erosion loss !Figure A-12al. 101 a . Heavily vegetated buffer and flow through the site is acceptable. c. Lightly vegetated buffer and flow through site is acceptable. b . Heavily vegetated buffer and flow through the site is unacceptable. d. Highwater or abandoned channel through heavily vegetated buffer and flow through site is acceptable. Figure A-12. Schematic of recommended options if the probabi I ity of flow through the site is high. 102 • If the buffer Is heevi ly vegetated, end flow through the site is unac- ceptable, construct e dike surrounding the materiel site designed for e flood with en acceptably low probebil lty of occurrence !Figure A-12bl. • If the. buffer Is I ightly vegetated, build a dike along the river side of the buffer designed for e flood with en acceptably low probebl llty of occurrence !Figure A-12cl. • If the buffer contains e high-water or abandoned channel, build e dike along the river side of the buffer to keep flow out of the chan- nel; the dike should be designed fore flood with en acceptably low probebi I ity of occurrence (Figure A-12dl. As an example of buffer height design, consider the materiel site loca- tion shown in Figure A-13. The buffer width has been estimated by historical Cross Section 5 1 1 .. ··_.,:I Cross Section 6-- Pit Material Site Figure A-13. Schematic of an example of buffer height design. 103 erosion techniques. Cross sections are surveyed as shown ltwo additional cross sections were collected further downstream). A backwater analysis was run to find that discharges of 103 m3 ts and 89 m3 ts overflowed the buffer at Cross Sections 3 and 7, respectively. A flood frequency analysis indicated that these discharges had recurrence intervals of 35 and 25 years. The design I ife of the buffer is 25 years. Thus, from Table A-1, at Cross Section 7 there is a 64 percent chance of getting flow into the downstream end of the material site within the 25-year I ife. This chance is acceptable to the user because the flow would primarily be backwater and would have relatively low erosion potential. At Cross Section 3 the upstream buffer has a 50 to 60 percent chance of overtopping the buffer. The user finds this to be unacceptable, but since there is a relatively smal I chance of substantial flow entering the pit from the upstream side, he recommends riprapping the upstream bank of the pit. REFERENCES Bovee, K. D., and R. T. Mi lhous. 1978. Hydraulic Simulation in lnstream Flow Studies: Theory and Techniques. lnstream Flow Information Paper No. 5. Cooperative lnstream Flow Service Group. Fish and Wildlife Service. Fort Col I ins, Colorado. 125 pp. Brice, J. 1971. Measurement of Lateral Erosion at Proposed River Crossing Sites of the Alaska Pipeline. U.S. Geological Survey. Water Resources Division. Alaska District. 39 pp. Chow, V. T. 1959. Open-Channel Hydraulics. McGraw-Hi I I Book Company, New York. 680 pp. Doyle, P. F., and J. M. Childers. 1976. Channel Erosion Surveys Along TAPS Route, Alaska, 1976. Open-File Report-77-170 !Basic Datal. U.S. Geolog- ical Survey. Anchorage, Alaska. 90 pp. Lamke, R. D. 1979. Flood Characteristics of Alaskan Streams. Water Resources Investigations 78-129. U.S. Geological Survey. Anchorage, Alaska. 61 pp. 104 Scott, K. M. 1978. Effects of Permafrost on Stream Channel Behavior in Arctic Alaska. Professional Paper 1068. U.S. Geological Survey. U.S. Government Printing Office, Washington. 19 pp. U. S. Army Corps of Engineers. 1976. HEC-2 Water Surface Profiles: Users Manual. Computer Program 723-X6-L202A. The Hydrologic Engineering Center. Davis, California. 17 pp. +Appendix. u. S. Water Resources Counci I. 1977. Guidelines for Determining Flood Flow Frequency. Bullet in No. 17A of the Hydrology Committee. Washington. 26 pp. + 14 Appendix. 105 APPENDIX B FIELD INSPECTION: DESIRABLE DATA, PROCEDURES, AND EQUIPMENT APPLICANT SITE PLANNING FIELD INSPECTION As part of the site planning process the applicant is recommended to visit the proposed site or alternate sites, or both, during the open-water season to gather the following information: A. Technical data to substantiate aerial photographic interpretation I e.g., sufficient quantity and quality of material, and percent fines!. B. General site specific biological data regarding the presence of areas or species of special concern that may be directly influenced should site development occur. C. Site specific hydraulic data relevant to site planning and agency review le.g., discharge, stage, and cross sections). D. Ground photographs of site physical and biological characteristics which wi I I be used in support of work plan development and submittal to appropriate agencies. E. If a snow-covered site wi I I be opened, alI work area locations should be surveyed during the open-water site visit. This survey should be from reference locations that can be located during site opening. Boundaries, such as those of active channels, buffer locations, vege- tated areas, and gravel deposits, can then be accurately relocated during site preparation. This wi I I reduce the potential for damage to areas that should not be disturbed. 107 - F. If winter active-channel mining is contemplated, an additional site visit during winter should be conducted. Its purpose is to determine the presence of water at or below the proposed site. Field Approach Material Avai labi I ity. A variety of techniques are avai I able to evaluate grandular materiels present at a site. These include borings, test pits, and resistivity measurements. Biological Evaluation. The entire site should be walked (during which time ground photos should be obtained) to subjectively assess the overal I fish and wildlife habitat quality in sufficient detai I to make Decisions I through 4 in Section I B. It may be appropriate to make this a combined appl icent- agency site visit. Hydraulic Date. Cross Sections: Cross sections of the river channellsl end floodplain should be surveyed to provide input to the hydreul ic analysis and the level to which excavation can extend. The number, location, and length of the cross sections should be based on the following criteria !Figure B-1 J: • There should generally be at least five cross sections; three or more would generally be necessary to describe the site end one or more would be required upstream and downstream from the site. • Cross sections through the site should be located at the upstream and downstream ends as wei I as one or more in between to define the extent of mining. • In addition to the locations necessary to define the site, cross sec- tions should be located at each significant change in floodplain width. • The upstream and downstream cross sections should be located at least two active channel-top widths from the upper and lower I imits of the materiel sites end associated buffers. 108 TBM 1 TBM2 TBM3 TBM4 LEGEND TBMS 0 Temporary Bench Mark Ill Cross Section Number Figure B-1. Schematic showing cross section number and loca.tions, temporary bench marks and thalweg profile at a hypothetical material site. 109 • The length of the cross sections should include the entire active floodplain width and should continue to an elevation on both ends equivalent to at least the highest point in the material site or the buffer, whichever is greater. • Cross sections should be aligned perpendicular to the direction of flow during flood events. • The distances between and direction of the cross sections should also be surveyed. The surveys should be performed using standard surveying techniques. A descrip- tion of these techniques and the desired accuracy is given in Bovee and M i I hous ( 197B I • Temporary Bench Marks: Temporary bench marks !TBMsl should be placed at one end of each of the cross sections and one near the active channel where the discharge measurements are taken !Figure B-1 l. The TBM elevations should be tied into a common datum !often arbitrary datum at the upstream cross section) as described in Bovee and Mi lhous ( 19781. Stage and Discharge: The stage !water surface elevation) should be re- corded at the time the discharge measurements are taken. Discharge measure- ments should not be taken while the discharge is rapidly changing. Discharge measurements should be taken at a cross section in a relatively uniform chan- nel reach; that is, the water surface slope and bottom slope should be similar and the depth, area, velocity, and discharge should not change significantly through the reach. Discharge measurements are taken by measuring the total depth and the velocity at specified depths at 25 to 30 stations across the channel. The station (distance from a TBMl should also be recorded. Velocity measurements should be taken at the following recommended depths below the water surface relative to the total depth !dl: -0.2d, 0.6d, and O.Bd is most preferred 110 -0.2d and O.Bd is next most pr.eferred -0.6d is recommended only if the depth ldl is less than 0.75 m If the discharge is changing rapidly and the measurements must be taken at that time, the 0.6d method should be used to complete the measurements faster. Additional detai Is on discharge measurements can be found in Bovee and Mi lhous I 19781 or Buchanan and Somers I 19691. Bed Material Size Distribution: The size distribution of the surface layer of bed material is required for evaluating the hydraulic roughness of the channel and floodplain. These data are obtained by an analysis of photo- graphs using a grid-by-number technique as described by Kel lerhals and Bray I 1971 l or Adams I 19791. The photographs should be taken, vertically downward, of at least a I m square area of undisturbed surface layer gravels. A scale should be included in the photograph. Thalweg Profile: A thalweg profile should be surveyed of the channel bed at those sites where the material site is being proposed on a gravel bar adjacent to the channel or in the channel itself !Figure B-1 l. These data are needed in the determination of the maximum depth to which gravel can be ex- tracted. The profile should extend at least five channel widths beyond the ends of the mined site. Photographs. Photographs should be taken to show the main habitat fea- tures of the river reach being studied !e.g., riffles, runs, pools, islands, gravel bars, riparian shrub thickets, mud flats, backwater areas, incised and undercut banks!. If possible, photographs should be taken from an elevated vantage point, such as a high bank. A sequence covering the entire reach of stream is desirable. A record should be made of each photograph, including date, time, location, direction of photograph, sequence, and main features being photographed. If the visit is a follow-up to a previous field visit, photographs identical to those obtained previously should be taken, as wei I as those showing new features. If a winter visit occurs, photograph aufeis and river ice characteristics. Ill AGENCY FIELD INSPECTION The initial agency field inspection is recommended to verify the data supplied by the applicant and to gather additional environmental data at the site to identify the significant biological habitats. With this informa- tion, any appropriate work plan that minimize environmental impacts can be recommended. The field inspection should evaluate the overal I habitat quality and include observations on site-specific parameters including: • General configuration of the river. • Channel top width !size of river). • Stage and discharge. • Mean velocity. • Bank and instream cover. • Substrate. • Pool:riffle ratio. • Presence of sensitive areas I i.e., spawning and overwintering areas). • Dominant terrestrial habitats. Desirable field inspection equipment for this site visit includes: • Devices to measure water depth and top width. • Device to measure water velocity. • Data sheets of field book for recording field observations. • 35 mm camera with color slide or print film. • Dip net. • Binoculars. During the initial field visit a site sketch should be prepared perferably using a copy of the aerial photo supplied with the work plan. This sketch should identify major aquatic and terrestrial habitat locations and configura- tions in relation to the boundaries and configuration of the work area, and locations of special features such as settling basins, stockpiles, access points, and others. 112 Subsequent agency visits (during site operation end site closure) should measure the seme parameters and document habitat alterations. Field Techniques Observations. Record and numerate alI fish end wildlife encountered in each habitat type. Stream Velocity. Stream velocity can be estimated by placing a biodegrad- able object with e density slightly less then that of water (such as an orange or lemonl, in the river end recording the time required to travel between two measured points. Express the me~surement in feet or meters per second. Bank and lnstream Cover. Bank and instream cover cen be expressed as percent of total cover and percent by each category. Categories for which avai I able habitat should be assessed include: • Banks-undercut bank, overhanging bank vegetation, end near-surface !submerged and emergent) bank vegetation. • lnstream-boulders, .logs, large debris, and other velocity bar- riers. • Depth-water depth acting as cover such as deep pools end runs. Substrate. Estimate the percent of substrate composed of the different particle sizes according to the modified Wentworth scale supplied in Appendix H. Separate by pool and riffle. Photogrepns. Photographs should be obtained to show the main habitat features of the river reach being studied le.g., riffles, runs, pools, islands, gravel bars, riparian shrub thickets, mud flats, backwater areas, incised and undercut banksl. If possible, photographs should be collected from en elevated ventage point, sucn es a high bank. A sequence catering the entire reach of stream is desirable. A record should be made of each photograph, 113 including d~te, time, loc~tion, direction of photogr~ph, sequence, end mein features. Photographs identical to those obtained previously should be taken, as wei I es those showing new features if the visit is a follow-up to a pre- vious field visit. Riparian Zones. These arees provide primary feeding, nesting, end cover hebitet for pesserines and smel I ·and medium sized mammals. During winter they also provide primary overwintering habitat for moose and ptarmigan. Areas that consist of advanced or mature sere I stages, generally have wei!- developed ground cover, shrub layer or overstory cover, or both, I in Northern and Southern Interior regions) thet provide desirable hebitet. Sites that contain riperien zones with high diversity of cover types !herbaceous marsh, mature shrub "thickets, mixed shrub thicket-early overstory forest and over- story forestl may be considered more desirable than sites containing riparian zones of homogeneous cover types. Watch for indicators of past activity levels: old passerine nests, smel I memmel runways and burrows, red squirrel feeding posts, moose browse, and moose and ptarmigan droppings in over- wintering areas. Water Bird Habitat. Feeding, nesting, and cover habitat for waterfowl, shorebirds, terns, and gul Is should also be assessed. Determine evei labi I ity of, end if possible uti I ization level of: • Backwater areas, mud flats, and I ittoral areas es feeding habitat by shorebirds, terns, and waterfowl. • Pools and side-channels as feeding habitat by terns, gul Is, and water- fowl. • Open and sparsely vegetated gravel bars as nesting habitat by gul Is, terns, and shorebirds !most frequently, semip·almated plovers, ruddy turnstones, spotted sandpipers). • Herbaceous riparian zones as nesting habitat by waterfowl and shore- birds. 114 Sites with a diversity of water bird habitats are more desirable than sites with only one or two types present. REFERENCES Adams, J. 1979. Gravel size analysis from photographs, pp. 1247-1255. ~ ASCE, J. Hydraulics Div. Proc. Paper 14908, Vol. 105, No. HYIO, October. Bovee, K. D., and R. T. Mi lhous. 1978. Hydraulic Simulation in lnstream Flow Studies: Theory and Techniques. lnstream Flow Information Paper No. 5. Cooperative lnstream Flow Service Group, Fish and Wildlife Service, Fort Col I ins, Colorado. 125 pp. Buchanan, T. J., and W. P. Somers. 1969. Discharge Measurements at Gaging Stations, 65 pp. ~Techniques of Water-Resources Investigations of the U.S. Geological Survey, Book 3, Applications of Hydraulics. U. S. Govern- ment Printing Office, Washington, D. C. Kellerhals, R., and D. I. Bray. 1971. Sampling procedures for coarse fluvial sediments, pp. 1165-1180. ~ ASCE, J. Hydraulics Div. Proc. Paper 8279, Vol. 97, No. HY8, August. I 15 INTRODUCTION APPENDIX C RIVER-TRAINING STRU~TURES AND BANK PROTECTION DEVICES River-training structures and bank protection devices may be required during gravel removal operations or site closure, or both. Their purposes can include protection of the site from flow during operation or after closure and reduction of the potential for downstream siltation. River-training structures also may be used to protect the bank of e buffer from excessive erosion. River-training structures end bank protection devices generally should not be used unless absolutely necessary because they usually disrupt natural river processes, often resulting in scour end erosion elsewhere in the system. In addition, bank protection devices can alter banks end their adjacent riparian zones. Revetments constitute· the major group bank protection devices. River- training structures in gravel removal operations primerly consist of dikes; other types of these structures include retards, guide banks, spurs, end jetties. Several publications are avai I able that discuss the design of such structures; these include California Division of Highways I 19601; Kereki et al. I 19741; Nei I I I 19731; U.S. Army Corps of Engineers I 19701 and Winkley 119711. The following paragraphs discuss briefly dikes and revetments. DIKES Dikes are long embankments used to control the overflow of water into the material site. Dikes may be constructed along an active channel or across a high-water channel, or both. Dikes may also be used to block active side channels in those cases where the bed is to be scraped. For these purposes, the dikes should be impermeable, high enough to prevent overtopping, and protected from erosion. Impermeable dikes are often constructed of stone or earth, or both. 117 The design of dikes should include consideration of the following <Figure C-1 l. · Continue ends of · dike beyond flood Rip rap 2:1 Slopes---, SECTION A·A Figure C-1. Dike design considerations. • Side slopes should be stable and riprapped to withstand the flood for which they are being designed <generally 2: I slope is recommended; see revetment design discussion!. • Top width is control led by the requirements of the equipment con- structing the dike. • The ends of the dike should be located and designed to keep water from flowing around them. • The top of the dike should be at an eievation equal to that of the water surface of the design flow; this water surface profile should be determined using a hydraulic backwater analysis. 118 • Dikes should be bul It beyond the limits of the low-flow buffer. BANK PROTECTION BY REVETMENTS A revetment is e leyer of erosion resistent materiel placed on a benk or embankment to ermor against erosion. Methods end materiels for revetments other then riprep ere evai I able but ere not discussed here because they generally ere unacceptable for environmental reasons. ~ The most common form of revetment is riprep, a layer of rock which may be dumped, hand-placed, or grouted. Dumped rock riprep is most commonly used, although grouted rock riprep may be applicable if the evel leble ma- teriel is not lerge enough to meet the requirements of dumped riprap. Rock- filled wire baskets lgebionsl may elso be used when evei I able materiels ere of insufficient size to meet dumped riprep requirements. There ere several factors important in the design of dumped rock riprep; these include: • Shape, size, end gradation of the rock. • Density and durability of the rock. • Velocity end depth of flow near the rock. • Steepness of the slope being protected. • Thickness of the riprap layer. • Fi Iter blanket presence end design. • End and toe protection. These factors ere discussed briefly in the following sections. Shape, Size, end Gradation. The shape, size, end gradation of the rock riprep ere the primary properties in resisting erosion. The shape should be angular to provide an interlocking of the rocks. Large rock is more erosion resistent then smel I rock. Selection of the proper rock size is a complex function of flow characteristics end slope of the embankment being protected. Kereki et al. 119741 present a method for estimating rock size. Nei II 119731 119 presents e greph to use es e guide in selecting riprep size (Figure C-21. 7 ~ , ,. /" I.-' 6 ~ , .. If/ ~ ,... " "'.; / ,.,.. 5 ," ,. ,/ v: ~ .... ... / >" / / 0 ...... 4 ~/ ~ / .. ~ , 1/ ," ti ~ ~- 2 ~ ~" ,, kJ 1 L' 0 0 100 300 500 700 900 1100 EOUIVALANT SPHERICAL DIAMETER OF STONE (mm) CURVE 0calif. Hgws . SPECIFIED STONE SIZE %FINER @Bur. Public Ads. ®Bur. of Reclarnn . 0eorps of Engrs. @Recommended Curve to~ a Guide (Neill,19731 L:::J1 2 D33 Dso BANK SLOPE 2c1 not given not given horizontal to 2: 1 Assumed stone spec1fic grav1ty = 2. 65 Figure C-2. Graph of riprap size vs. local flow velocity (modified from N'eill 19731. It should be used with ceution beceuse not elI espects ere incorporeted. Wei 1-greded meteriel improves the interlocking of the rock end reduces spaces between rocks. A recommended gredetion is shown in Figure C-3. Density end Durebi I ity. The rock used for riprep should be herd, dense, end durable to withstand cycles of wetting end drying, end freezing end thawing. These cycles cen ceuse cracking of the rock, resulting In reduction of size end erosion resistance. Density end durebil lty ere generally deter- mined by leboretory tests. 120 100[------------------------------- 90! eoi 70 D50 = Median Riprap Diameter Q; eo .s:-u..c 50 "E ·~ 40 ~~ &:b 0.1050 0.5050 Sieve S1ze 050 2Dso Figure C-3: Suggested gredetion for riprep lefter Kereki et el. 19741. Velocity end Depth of Flow. A primery factor influencing erosion Is the local velocity of the flow. Direct flow measurements ere recommended, but these mey be difficult to obtain during flood events. In the absence of measured deta, Nei I I ( 19731 recommends the locel velocity against a slope be teken as: • Two thirds of the average velocity in straight reaches. • Four thirds of the everege velocity in severe bends. The sheer stress on the rock riprap is proportional to the depth of flow ebove the riprep. Thus the rock size should increase with increasing depth. Steepness of Slope. The stebi I ity of riprep revetment decreases with increasing steepness of slope. The steepest slope on which riprep wit I rest without flow forces is the engle of repose of the materiel, which is gen- erally between 35 end 45 degrees. Flow egeinst the rock wit I decrease the angle of stebil ity. It is recommended that slopes of 2: I (2 horizontal to vertical! be used. Slopes steeper than 1.5: I generally should not be used. 121 Thickness of Riprap. The ihickness of the riprap ~hould be sufficient to provide the desired protection of the slope. The minimum thickness should be equal to the longest dimension of the largest rock or be 50 percent larger than the median rock size, whichever is larger. This minimum thickness should be increased by 50 percent if: • Wave action is possible. • Gradation is not as recommended. • Riprap is to be placed in flowing water. • A fi Iter is not used when recommended. Fi Iter Blankets. A fi Iter blanket may be recommended for placement beneath the rock riprap layer to prevent the loss of bank material through the voids in the riprap. If the material washes out, cavities wi I I form beneath the riprap and failure of the riprap revetment can occur. The require- ments for a fi Iter depend on the size and gradation of the bank material and on the voids in the riprap layer. If the compos it ion of the bank material is such that it is eesi ly eroded, a fi Iter layer is generally recommended. Poor riprap gradation is also a reason to recommend a fi Iter. Filters may be wei 1-graded gravel or a synthetic fi Iter cloth. Gravel filters should use gravels ranging from about 5 mm to 90 mm I Karak i et a I. 1974 I. F i Iter thickness shou I d be no I ess than 0. 15 m; f i Iter thickness equal to half the riprap thickness is recommended. More than one layer, of different gradation and median size, should be considered if there is a very large difference in size between the bank material and the riprap rock. Recommended guide I ines for gradation of the fi Iter ere given by Karaki et al. I 19741; they are summarized in relations below. These relations should be applied to each layer in turn, starting with the bank material as the fine material and using the needed fi Iter material as the coarse. The first fi Iter selected then becomes the fine material for the next fi Iter layer computation. After determining the size and gradation of each fi Iter, these relations should be used with the last selected fi Iter 122 as the fine materiel and the riprep as the coarse materiel. If the results are within the indicated limits, an additional fi Iter layer is not needed. • o50 (coarse) < 40 o50 lfine) • 5 o15 !coarse) < 40 o15 !fine) • o15 !coarse) < 5 o85 !fine) Where o50 is median diameter, o15 is the diameter particle of which 15 per- cent of the materiel is finer, and o85 is the diameter particle of which 85 percent of the material is finer. An example of fi Iter gradation design is given in Figure C-4. Fi Iter cloths have been used with success for more then a decade. They can support large riprap material with no damage to the cloth. A disadvan- tage of fi Iter cloths is that the riprap must be placed with care to prevent damage to the cloth. End and Toe Protection. The ends of the riprep revetment along the channel may be subject to erosion. The erosion could remove material from behind the riprap and cause failure of the riprap. Extending the riprap revetment to areas not having erosive velocities is a recommended end protec- tion !Figure C-5a). If this is not possible, the thickness of the riprep layer should be increased to twice that otherwise needed. This extra thick- ness should be placed in a recess cut into the bank to maintain a uniform riprap face !Figure C-5b). 123 .-.• ..,---Riprap Filter 2 Filter 1 ~'0~"'---Emba n km en I GIVEN: STEP 1: FILTER 1 GRADATION DESIGN D15(mm) Dso(mm) D85(mm) EMBANKMENT 0.10 0.20 0.50 RIP-RAP 300 500 800 D50(FILTER 1) <40x D50 (EMBANKMENT)=8mm 0.5mm = 5 x D15(EMBANKMENT) < D15(FILTER 1) < 40 x D15(EMBANKMENT) = 4mm D15(FILTER 1) <5x D85 (EMBANKMENT)=2.5mm SELECT D15 = 1.5mm, D50 = 3.0mm, D85 = 6.0mm STEP 2: FILTER 2 GRADATION DESIGN D50(FILTER 2) <40 x Dso(FILTER 1) = 120mm 7.5mm =5x D15(FILTER 1) < D15(FILTER2) <40x D15(FILTER 1)=60mm D15(FILTER2) <5x D85(FILTER 1)=30mm SELECT D15 = 20mm, D50 = 40mm, D85 = 80mm STEP 3: CHECK FILTER 2 DESIGN AGAINST RIP-RAP Dso(RIP-RAP) < 40 x Dso(FILTER 2) 500mm < 1600mm "'OK 5 x D15(FIL TEA 2)< D15(RIP-RAP) <40 x D15(FILTER 2) 1 OOmm < 300mm < 800mm ., OK D15(RIP-RAP) < 5 x D85(FILTER 2) 300mm <400mm "'OK STEP 4: SUMMARY ACCEPTABLE FILTER GRADATION DESIGN TABLE: D15(mm) Dso(mm) Das(mm) FILTER 1 1.5 3.0 6.0 FILTER2 20 40 80 Figure C-4. Example of fi Iter gradation design. 124 a b Figure C-5. Schematic showing plan view of end protection configurations: el extension out of the zone of erosion with a potential reduction In thick- ness, and bl increasing the thickness at the ends of the revetment. The base of the riprap revetment can be undercut by scour of the bed if the toe is not protected. Extending the riprap layer below the level of the bed and backfi I ling is recommended !Figure C-6al. If this cannot be done, the riprap layer should be continued on the channel bed with an Increased thickness to provide material to fi I I any scour holes that de- velop, thus preventing the scour from undercutting the riprap !Figure C-6bl. 125 Water Leve7 '------:fhickness Depends on Potential for Scour a b Figure C-6. Schematic showing cross section of toe protection configurations: al extension of the riprap below the dry bed and backfi I I ing, and bl place- ment of extra material along the bed to launch itself into developing scour holes. REFERENCES California Division of Highways. 1960. Bank and Shore Protection in California Highway Practice. Sacramento: Documents Section, State of California. Karaki, S., K. Mahmood, E. V. Richardson, D. B. Simons, and M. A. Stevens. 1974. Highways in the River Environment, Hydraulic and Environmental Design Considerations, Prepared for the U. S. Federal Highway Adminis- tration. Neill, c. R., ed. 1973. Guide to Bridge Hydraulics. Published for Roads and Transportation Association of Canada, by Univ. of Toronto Press. 191 pp. U. S. Corps of Engineers. 1970. Hydraulic Design of Flood Control Channels, Engineering and Design. Manual No. EM-I I 10-2-1601. Winkley, B. R. 1971. Practical Aspects of River Regulation and Control, In: River Mechanics, Vol. I. Hsien Wen Shen, ed., Prof. of Civi I Eng., Colorado State University. 126 APPENDIX D DESIGN OF PITS There are two basic designs to consider when mining floodplain gravel by pit excavation: pit not connected, or pit connected to an active channel. A properly designed unconnected pit can provide waterfowl, shorebird, and amphib- ious mammal habitat. If the pit is connected to the active channel, the pit can also provide fish habitat. The outlet channel of the connected pit allows fish that become trapped in the pit during high water to emigrate from the pit at any time. If the pit is unconnected, it should be protected from the 20- year flood. Fish trapped during these floods are considered lost from the river population. SHAPE AND DEPTH The desired configuration for a gravel pit excavated in an inactive floodplain or terrace is long and narrow, in the shape of a channel, with a variety of depths !Figure D-1 l. If the pit is connected to the river or fish are to be stocked in the pit, the mean depth should be greater than 2.5 m to allow fish survival during winter. For a pit with a configuration as shown in Figure D-1, the following are two examples of depth regimes that wi I 1 result in a mean depth of 2.5 m: A. For a minimum mean depth with a minimum of littoral area Mean of depth i nterva I lml 0.5 1.5 2.5 3.5 4.5 Maximum depth: 5 m Mean depth: 2.5 m 127 Percent of pit area 25 10 10 50 5 ~ Figure D-1. Desired general configuration of a gravel pit connected to the active channel. B. For 8 minimum me8n depth with 8 m8ximum littor81 8re8 Mean of depth interval lml 0.5 1.5 2.5 3.5 4.5 5.5 Maximum depth: 6.0 m Me8n depth: 2.5 m Percent of pit 8re8 35 10 10 15 25 5 A pit with greater I ittoral area generally allows greater productivity and is preferred for waterfowl, shorebirds, 8nd fish. In both of the 11bove examples an increased me11n depth wi I I decre11se the probabi I ity of fish winter noortal ity. If more gravel is required, increasing depth is preferred over increasing the surf11ce area of disturbance. METHOD FOR CALCULATING MEAN DEPTH OF PIT To obtain 11n estimate of the me11n depth of 11 designed pit, the following procedures can be used. A. Determine the 1-m lor other unit of me11surel contour intervals for the pit. B. Determine the percent of surface arealsl consisting of a particular 1-m depth interval [i.e., 0-1 = 0.35; 1-2 = O.IO; ••• ;In-1 l-n = sn, where n =number of depth intervals]. 129 C. Multiply the midpoint of eech 1-m depth intervel ldl by the percentege of aree composed of thet interval [!i.e., d x s = 10.51 10.351; 11.51 (O.IOI, ••• ,Idnl(snl). D. Meen depth= sum of elI products in c. [i.e., meen depth t ds (0.5110.351 + 11.5110.101 + ••• + ldni(Sn). The Teble below conteins exemple celculetions of meen depth of the pit shown in Figure D-1. The letters refer to the four steps listed ebove. c A B Midpoint Product of Contour Surfece eree of contour midpoint end i ntervel (he or interval percentage area lml other unit I ($) (ml lml 0-1 1.28 33 0.5 0.17 1-2 0.64 17 1.5 0.26 2-3 0.52 14 2.5 0.35 3-4 1.08 28 3.5 0.98 4-5 0.30 8 4.5 0.36 Tote I 3.82 100 D 2.12 = meen depth 130 APPENDIX E FISH PASSAGE STRUCTURES PROVIDING FOR FISH PASSAGE OR CULVERT GUIDELINES Fish passage structures should be provided when it is necessary to cross drainages. Bridges are preferable for fish passage; however, they are often economically unfeasible because of the short project life and remoteness of most floodplain gravel removal operations. If mature timber is avai leble, it may be used for effective and economical log culverts. Metal culverts, although generally undesireable in temporary roads, are usually utilized, but must be instal led properly to provide adequate fish passage. The following guidelines on fish passage structures ere a synopsis of those developed by Dryden and Stein I 1975) and U. S. Department of Agriculture I 1979l for the protection of fish resources. The former document presents guide I ines to be considered in Northwest Territories road design while the latter deals specif- ically with how to properly design fish passage structures in Alaska roadway drainages. Refer to these documents for more detai I and specifics. Hydrological Design Structure Velocities. A. In general, the average velocity should not exceed 0.9 m/s during fish migration periods. Many species require velocities considerably less than this during migration periods and fish passage can be impeded at velocities of 0.3 m/s !Figure E-1 l. B. A 3-day delay period 13 days of velocities in excess of those required for passage! should not be exceeded during the mean annual flood 12.33-year recurrence interval flood). A 7-day delay period should not be exceeded in the design flood. 131 5 40 -30 E u - 10 10 20 30 40 50 60 70 80 WATER VELOCITY (em/sec) Figure E-1. The relationship between fish fork length and ability to move 100m against water velocities of 0-80 em/sec in 10 min. The same curves may elso be used to indicate the ebi lity to make progress against these currents over shorter distances. For instance, to cross e 50-m barrier in 10 min the curves should be shifted 8 em/sec to the right; to cross e 25-m barrier in 10 min the curves should be shifted 12 em/sec to the right. The line for char is derived from the hypothetical equation V = 17 L'·" end represents the measured value In these experiments (from Jones 19731. 132 Minimum Weter Level. The weter level in the culvert should not be less then 20 em during the open-weter seeson unless fish pessege is not required. Structure Design Shepe. A. If suiteble timber is avei leble, netive log stringer or rough-sewed timber bridges end log culverts ere the most desireble temporery structures for the passege of fish. They meintain the neturel streem bed end gradient end ere easy to remove. B. Arch culverts with en open bottom are preferred culverts for permenent roads. These culverts retein neturel bed material. Closed erch cul- verts ere second in preference. C. Horizontel elI ipse culverts cen meintein streem flow width end neturel bed meteriel if the culvert invert is placed below the stream bed elevation. D. Circular culverts ere impractical for fish pessege unless instal led as described by U. S. Department of Agriculture ( 19791, summarized in the following section. Instal let ion end Design. A. Culvert inverts should be laid a minimum of 15 em below normal stream bed elevation. The Alaska State Pipeline Coordinator's Office often recommends a burial depth of 201 of culvert diameter. B. Inverts should be designed to prevent hydrostatic up I ift at the down- stream or upstream end. C. The culvert gradient should be kept as close to 01 gradient as pos- sible so that upstreem or downstream velocity barriers ere not created. 133 Capacity. Culverts should have sufficient capacity to pass the design flood with no backwatering or pending at the upstream end. Location. A. Culverts should not be placed where a channel cutoff or diversion wi I I result. B. The culvert should be placed so that its discharge is not directed at an unstable bank. Multiple Culverts. A 1.8 m spacing should be present between adjacent culvert wal Is. This wi I I provide a downstream backwater area for fish to rest in before attempting passage. REFERENCES Dryden, R. L., and J. N. Stein. 1975. Guidelines for the Protection of the Fish Resources of the Northwest Territories During Highway Construction and Operation: Environment Canada. Fisheries and Marine Service Tech. Rept. Series·No. CEN/T-75-1. 32 pp. Jones, D. R. 1973. An Evaluation of the Swimming Performance of Several Fish Species from the MacKenzie River. Dept. Environment, Fisheries and Marine Service, Winnipeg, Man. 53 pp. U. S. Dept. of Agriculture. 1979. Roadway Drainage Guide for Instal I ing Culverts to Accommodate Fish. Engineering and Aviation Management Div- ision, Forest Service. Alaska Region Report No. 42. 121 pp. 134 APPENDIX F SETTLING PONDS AND WASTEWATER TREATMENT WASTEWATER TREATMENT The Federal-State effluent guidelines indicate that total suspended sol ids ITSSI is the main effluent parameter that must be monitored during mining and processing of construction sand and gravel I Hal I and Kosakowski 19761. The present EPA requirement is that the TSS of a gravel mining effluent should not exceed 30 mg/t at any time. In order to accomplish this final concentration, a series of settling ponds and often a coagulant are normally required. Specific needs wi I I vary according to the amount of washing neces- sary and the sci I characteristics of the material. In a washing operation, wash water can usually be recycled without need for discharge. In this case the amount of settling required wi I I depend on the need of the operator for clean water. Generally, recycled water with a TSS of less than 200 mglt is suitable for reuse. Specific detai Is on how to design and operate settling ponds are dis- cussed in Monroe I 19731 and this document should be referenced if additional information is needed. Following is a brief synopsis of his major recommenda- tions. Settling Ponds-pond with an outlet A. Used to clarify water for reuse or effluent discharge. B. Cross-sectional area of the pond must be large so horizontal velocity is very slow. C. Water must enter pond over most of the width to make the entire pond effective le.g., to avoid short circuiting, channel formation). 135 D. The outlet must be wide to skim off the top clear water and maintain a low horizontal velocity. Fi Iter Ponds-pond without an outlet A. Used where there is no discharge or recirculation. B. Water table must be low enough that water wil I fi Iter out, not into the pond. Pond berms must be high enough to guard against floods. C. Wal Is and bottom of the pond must be porous to allow outflow. Ponds seal more slowly if they are kept ful I so alI the area of wal Is and bottom are working. D. Pond must be large enough so ii wi I I not seal. E. Coagulants should not be used in fi Iter ponds because they shorten the I ife of these ponds. F. It is best to precede the fi Iter pond with a settling pond for heavy particle settlement. Coagulation A. Used when there is a high concentration of solids that wi I I not settle or there is I imited area for settling ponds, or both. B. Must be thoroughly mixed to be efficient. C. Works better in warm water; settlement rate is doubled for every 35°C increase in temperature. D. Commonly used coagulants are: aluminum sulphate laluml, ferrous sul- phate lcopperasl, calcium hydroxide (hydrated limel, calcium oxide I quick I imel, sodium aluminate, sodium carbonate lsoda ashl, ferric chloride lferrisull, sodium silicate. 136 E. Multipond arrangement may be most suitable. F. Coagulant should be added to the water at inlet to each pond. REFERENCES Hall, E. P., and M. W. Kosakowski. 1976. Mineral Mining and Processing Industry. Development Document for Interim Final Effluent Limitations Guide I ines and Standards of Performance. Environmental Protection Agency, Effluent Guide I ines Division, Office of Water and Hazardous Materials. Wash., D. C. 432 pp. Monroe, R. G. 1973. Wastewater Treatment Studies in Aggregate and Concrete Production. Environmental Protection Technology Series EPA-R2-73-003. Environmental Protection Agency, Office of Research and Monitoring, Washington, D. C. 108 pp. 137 APPENDIX G EFFECTS OF BLASTING ON AQUATIC ORGANISMS Although infrequently required on floodplain sites, blasting may be uti I ized during certain phases of gravel removal. Teleki end Chamberlain ( 197Bl developed a series ~f curves and equations to estimate the fatality radius of a particular charge (based on en explosive with a detonation veloc- ity of 4940-5490 m/s) in relation to certain types of fish !Figure G-11. A number of studies have evaluated the effects of blasting on a particu- lar organism or groups of organisms. Table G-1 summarizes the results of some of these studies end indicates the range of sensitivities shown by aquatic organisms to pressure changes. The force generated by a particular charge can be determined at various distances by referring to Table G-2. REFERENCES Alpin, J. A. 1947. The effect of explosives on marine life. Cal if. Fish and Game 33111:23-27. Baxter, R. E. 1971. Effects of Explosives Detonated in Ice on Northern Pike, Kuskokwim River, 1970. Alaska Dept. Fish and Game Info. Leaflet 154. IB pp. Falk, M. R., and M. J. Lawrence. 1973. Seismic Exploration: It's Nature end Effect on Fish. Fish end Meine Service Central Region. Tech. Rept. Series No. CEN/T 73-9. Henson, H. 1954. Fur seal control program, Copper River end Bering River area. Alaska Dept. of Fisheries. 139 Hubbs, C. L., and A. B. Rechnitzer. 1952. Report on experiment designed to determine effects of underwater explosioQs on fish I ife. Cal if. Fish and Game 38131:333-366. Rasmussen, B. 1967. The Effect of Underwater Explosions on Marine Life. Bergen, Norway. 17 pp. Teleki, G. c., and A. J. Chamberlain. 1978. Acute effects of underwater con- struction blasting on fishes in Long Point Bay, Lake Erie. J. Fish Res. Bd. Canada 35: I 191-1 198. U. S. Navy. 1970. U. S. Navy Diving Manual. NAVSHIPS 0994-001-9010. 140 120 A II 100 BO 60 B 40 E 20 >95°/o __; a: 0 u.. 20 100 200 280 20 100 200 280 Cf) 120 :J 0 <( a: 100 >-f-- ::J BO <( ~ u.. 60 40 0 Ill <10°/o A B IV A B 20 100 200 280 20 100 200 280 MAXIMUM EXPLOSIVE WEIGHT PER CHARGE (kgl Figure G-I. Relationship of kilogram per charge to fatality radii (FRI: A= 10-20% mortality, B = 95% mortality. physocl istic, high lateral compression I pumpkin seed, crappie, white bass I. 11 physocl istic, moderate lateral compression (rock bass, smal lmouth bass, ye I low perch I. 111, IV= physostomic, fusiform I 111 = qui I I back, white sucker, yellow bul I head; IV= rainbow trout I I from Teleki and Chamberlain 19781. Equations (From Teleki and Chamberlain 19781 IA: log FR= I .2423 + 0.3340 log kg IB: Log FR= 0.8814 + 0.3390 log kg I IA: Log FR= 1,3340 + 0.3337 log kg I I B: Log FR= 0.9087 + 0.3323 log kg I I IA: Log FR 0.9261 + 0.3344 log kg 11 IB: Log FR 0.8199 + 0.3429 log kg IVA: Log FR= 0,8465 + 0.3382 log kg IVB: Log FR= 0.7297 + 0.3624 log kg 141 ~ "' Teble G-1. Lethal end Sublethal Blesting Pressures of Selected Aquetic Organisms A. Blasting with verious "high explosives". Force Organism lki lopascalsl 8 Six month salmon & herring fry Fish with air bladder Northern pike Arctic cisco and smal I Coregonidae Fur sea I Fish without eir bladder Oyster Blue crab Shrimp Salmon and herring fry w/o eir bladder 0.4 6-7 7 25 74 74 56-126 113-124 169 Effect Lethal Lethal Lethal Lethal Letha I Largely uninjured Low mort a I i ty Lethal No effect "Not greatly affected" Reference Rasmussen 1967 Hubbs & Rechnitzer 1952 Baxter 1971 Felk & Lawrence 1973 Hanson 1954 Alpin 1947 Rasmussen 1967 Rasmussen 1967 Rasmussen 1967 B. Blasting with "Hydromex" !Detonation velocity 4938-5486 m/secl. Organism Pumpkin seed Crappie White bess Gizzerd shed Ye I I ow perch Sma I I mouth bass Rock bess Freshwater drum Qui II back White sucker Yellow bullheed Reinbow trout Carp 8 0ne k i I op.,sc" I Minimum lethal pressure ( k i I opesce Is l 8 30 30 30 39 40 65 65 73 76 73 73 85 7 6.896 pounds per squ8re inch. Fatal pressure 195% mortal it~l (ki lopescalsl 69 73 88 73 76 100 150 Reference Teleki & Chamberlain 197B (for alI organisms on I istl Table G-2. Force in Ki lopascals Expected at Different Distances as e Result of Detonating Different Charges lkgl of Explosives ltetryl or TNTia Radius from Force lkilopascalsl resulting from the following weights of explosion ex~losives tksl lml I 2 5 IO 20 30 40 50 100 200 I 748 942 1279 1611 2030 2324 2558 2755 3471 4374 2.5 299 377 512 645 812 930 1023 1102 1389 1749 5 150 188 256 322 406 465 512 551 694 875 10 75 94 128 161 203 232 256 276 347 437 15 50 63 85 107 135 155 171 184 231 292 25 30 38 51 64 81 93 102 110 139 175 30 25 31 43 54 68 77 85 92 116 146 45 17 21 28 36 45 52 57 61 77 97 60 12 16 21 27 34 39 43 46 58 73 "'" 75 10 13 17 21 27 31 34 37 46 58 "' 100 7 9 13 16 20 23 26 28 35 44 150 5 6 9 II 14 15 17 18 23 29 200 4 5 6 8 10 12 13 14 17 22 300 2 3 4 5 7 8 9 9 12 15 500 I 2 3 3 4 5 5 6 7 9 8 Modified from U. S. Navy 1970. APPENDIX H STANDARD FORMULA AND CONVERSION FACTORS CONTINUITY OF FLOW Q = A1V1 = A2V2 where Q = discharge A1 =cross sectional area of the flow at I v 1 =mean flow velocity at I A2 =cross sectional area of the flow at 2 v2 =mean flow velocity at 2 VELOCITY OF CULVERT FLOW Culvert Flowing Full !Outlet Control! where v = Q T v mean flow velocity in culvert Q = discharge through culvert A= cross sectional area of culvert Cross sectional areas of plate steel arch, pipe-arch, and circular culverts of various sizes are I isted in Tables H-1, H-2, and H-3. Estimates of cross sectional areas of circular culverts whose inverts ere buried below the stream bed can be obtained from Tables H-1 or H-2, using measured or estimated span and rise values. Culvert Flowing Partially Full I inlet Control I Outlet velocity may be approximated by computing the mean velocity for the culvert cross section using Manning's equation. Manning's equation can be written: 145 Table H-1. Cross-Sectional Area of Plate Stee) Arch Culverts Span Rise Cross-Sectional Area m ft-in m ft-in m2· ft 2 1.83 6-0 0.70 2-31;, 0.93 10 2.13 7-0 0.86 2-10 1. 39 15 2.44 8-0 1.02 3-4 1.86 20 2.74 9-0 1.18 3-101;, 2.46 261;, 3.05 10-0 1. 35 4-5 3.16 34 3.35 11-0 1. 36 4-51;, 3.44 37 3.66 12-0 1. 52 5-0 4.18 45 3.96 13-0 1. 55 5-1 4.55 49 4.27 14-0 1. 70 5-7 5.39 58 4.57 15-0 2.01 6-7 6.97 75 4.88 16-0 2.16 7-1 7.99 86 5.18 17-0 2.18 7-2 8.55 92 5.49 18-0 2.34 7-8 9.66 104 5.79 19-0 2.49 8-2 10.96 118 6.10 20-0 2.53 8-31;, 11.52 124 6.40 21-0 2.69 8-10 13.01 140 6.71 22-0 2.72 8-11 13.56 146 7.01 23-0 3.00 9-10 15.89 171 7.32 24-0 3.15 10-4 17.47 188 7.62 25-0 3.31 10-101;, 19.23 207 7.62 25-0 3.81 12-6 22.95 247 146 Table H-2. Cross-Sectional Area of Pipe-Arch Culverts SPAN Span Rise Cross-Sectional Area m ft-in m ft-in m2 te 0.46 1-6 0.28 0-11 0.10 1.1 0.63 2-1 0.41 1-4 0.20 2.2 0.91 3-0 0.56 1-10 0.41 4.4 1.27 4-2 0. 79 2-7 0.81 8.7 1.47 4-10 0.91 3-0 1.06 11.4 1.65 5-5 1.02 3-4 1.33 14.3 1. 85 6-1 1. 40 4-7 2.04 22 2.13 7-0 1.55 5-1 2.60 28 2.41 7-11 1. 70 5-7 3.25 35 2.69 8-10 1.85 6-1 3.99 43 2.97 9-9 2.01 6-7 4.83 52 3.25 10-8 2.11 6-11 5.39 58 3.53 11-7 2.26 7-5 6.22 67 3.81 12-6 2.41 7-11 7.25 78 4.09 13-5 2.57 8-5 8.27 89 4.34 14-3 2.72 8-11 9.38 101 4.67 15-4 2.82 9-3 10.13 109 5.00 16-5 3.02 9-11 11.71 126 5.03 16-6 3.35 11-0 13.29 143 5.31 17-5 3.51 11-6 14.68 158 5.66 18-7 3.66 12-0 16.17 174 5.94 19-6 3.81 12-7 17.65 190 6.27 20-7 4.01 13-2 19.88 214 147 Teble H-3. Cross-Sect ionel Area 'of Circule.r Culverts Inside Diameter Cross-sectional area m ft-in m2 ft 2 0.30 1-0 0.074 0.8 0.46 1-6 0.17 1.8 0.61 2-0 0.29 3.1 0.76 2-6 0.49 5.3 0.91 3-0 0.66 7.1 1.07 3-6 0.89 9.6 1.22 4-0 1.17 12.6 1.37 4-6 1.48 15.9 1. 52 5-0 1.82 19.6 1.83 6-0 2.63 28.3 2.13 7-0 3.58 38.5 2.44 8-0 4.67 50.3 2.74 9-0 5.91 63.6 3.05 10-0 7.29 78.5 3.35 11-0 8.83 95.0 3.66 12-0 10.51 113.1 3.96 13-0 12.33 132.7 4.27 14-0 14.30 153.9 4.57 15-D 16.42 176.7 4.88 16-0 18.68 201.1 5.18 17-0 21.09 227.0 5.49 18-0 23.64 254.5 5.79 19-0 26.34 283.5 6.10 20-0 29.19 314.2 148 where v =.!. R2/3 s112 n V =mean flow velocity in culvert lm/sl n =Menning roughness coefficient R =hydraulic radius lml S = slope of culvert invert lm/ml Approximate values of roughness coefficient are I isted below: smooth I ined culverts corregated metal culverts culverts partially fi I led with gravels and cobbles n = 0.012 n = 0.024 n = 0.036 Estimates of the hydraulic radius of culverts can be obtained from Figure H-1. A nomograph for solving Menning's equation and an example problem ere given in Figure H-2. DISCHARGE MEASUREMENTS Standard Measurement Technique The U. S. Geological Survey has developed a technique for measuring the discharge in a river !Buchanan end Somers, 1969!. A relatively straight and uniform reach of river should be selected for taking discharge measure- ments. The width of the channel Is! should be divided into a number of sub- sections 125 or more ere recommended) that ere often, but do not have to be, the same width !Figure H-3). Velocities are measured at each of the ob- servation points at one or more depths depending on the flow depth, desired accuracy, end rete of change of the flow. Generally speaking, the accuracy of the mean velocity increases with increasing number of current measurements at one observation point. An exception to this is when the flow is changing rapidly, thus requiring that the discharge measurements be completed in a short time span. Equations for calculating mean velocity ere given in Figure H-3 for three common measurement techniques. Discharge in each subsection is the product of the mean velocity in the subsection and the cross-sectional 149 Definition of hydraulic radius: R=~ p Where R = hydraulic radius A = flow cross-sectional area P = wetted perimeter Approximate value of hydraulic radius for circular culverts: Flowdepthd greater than 0.45Dc, use constant value of R.::: 0.28 De Flow depth d less than 0.45 De, use ."!.::: 0.6d 0.45 De Approximate value of hydraulic radius for arch culverts: Flow depth d less than 0.2 x span, use R ~ 0.4d Span r0.2>Spao ----=- Figure H·1. Methods of estimating hydraulic radius of culverts. 150 .3 EQUATION: V= 1 ·~9 R% slf2 I English Units) I ~;;_F40 .2 1-v=ir R%sl2 (Metric Units) ~ 30 ~ A I Q r r-.01 .tO .09 .08 r I -l-20 .07 .06 .6 w .2 " z .05 .7~q ::J .04 C) 8~ z ~-02 r·9 ~6>.., z o'~- .03 -;; a: ~ :::l ~ ~ f-3 a:: .02 I ~ / 8 c L03 0 / ..... I Ill ::) / 7.2-... ~ 5 ""-/ 2 s> z ..... w 1:-.04 a:: -/ ~ '! I 0 0~~~ ,::o ~/ 5)-u:: ... 8 ~.05 "' \, E 0 1. .oo1 ~ ~ ·9 ._. 40 Qli ~6 ...1 ~ l" ~ 006 Q / 6>.., w .005 ~ "~ 1 > w .07 ul ~~-/ Example 3 z Given: ::1: .06 Invert Slope = 0.003 CJ 2m dia. circular ::) .09 0 corrugated culvert, a:: .10 partially lined .002 + Flow depth in culvert = 0.3m I .5 Find: Flow velocity .001 9 Solution: .0009 10 Select roughness r L2 .0008 .0007 coefficient of 0.02 .9 .0006 Connect slope and .8 roughness .ooos coefficient .7 Estimate hydraulic .2 ~3 .0004 .6 radius .0003 6--L20 -.45 dia. = 0.9m I t...5 ·flow depth 0.3m E..4 0.9m Draw line from hydraulic radius through -R = 0.6 x flow intersection of slope-roughness coefficient depth line and turning line to the velocity = 0.18m scale to get V = 0.88m/s FlgureH-2. Nomograph for solution of Manning's equation. 151 where where or or where. bs O=f:. q; i=1 b(n-1) EXPLANATION n Observation Points bn Distance from the Initial Point to the Observation Point dn Depth of Water at the Observation Point COMPUTATIONS q; = V; ( b;+12 b;-1 ]d; V;= ( V;.2d + V;.8d+2v;.6d )/4 'ii; =( V;.2d,. V;.Bd)/2 vi= vi.6d 'ii = mean velocity in section i v;.2 d =measured velocity at 0.2d below the water surface v;_6 d = measured velocity at 0.6d below the water surface v; = measured velocity at O.Bd below the water surface .Sd Figure H-3. Discharge meesurement technique. 152 erea of flow in the subsection. Total discharge in the channel is the sum of the discharges in the subsections (Figure H-31. Approximate Measurement Technique The discharge in a channel cen be approximated using simple field tech- niques. The cross-sectional area of flow can be estimated for the entire cross section as the product of the top width and the average depth. The mean surface velocity in the channel can be estimated by placing an object which just barely floats in the flow near the center of the channel and record- ing the time required to travel between two measured points. The mean velocity is typically 80 to 90 percent of the surface velocity. The product of the estimated mean velocity and cross-sectional area Is the estimated discharge. REFERENCE Buchanan, T. J., and Somers, w. P. 1969. Discharge measurements at gaging stations. Chap. AS, Book 3, Techniques of Water-Resource Investigations of the United States Geological Survey, U. S. Government Printing Office, Washington, D. C. 65 pp. 153 - IJ1 "" Teble H-4. Modified Wentworth Perticle Size Scele to be used for Visuel ly Estimeting Substrete Composition8 Size renge Perticle description mm inches Memmouth boulder >4000 >157 I 13 ft) Very lerge boulder 2000-4000 78-157 16.5-13 ftl Lerge bou I der 1000-2000 39-79 13.3-6.5 ftl Medium boulder 500-1000 20-39 Sme I I bou I der 250-500 10-20 Lerge cobble 130-250 5-10 Sme I I cobb I e 64-130 2.5-5 Very coerse grevel 32-64 1.25-2.5 Coerse grevel 16-32 0.63-1 .25 Medium grevel 8-16 0.32-0.63 Fine grevel 4-8 0.16-0.32 Pee grevel 2-4 O.OB-0. 16 Very coerse send 1-2 0.04-0.08 Send 0.062-1 0.0024-0.04 Si I t-cley <0.062 <0.0024 8 From Bovee, K. D. end R. T. Mi lhous. 1978. Hydreul ic simuletion in instreem flow studies: Theory end Techniques. U.S. Fish end Wildlife Serv. lnstreem Flow Info. Peper No. 5. 125 pp. Table H-5. Conversion Factors To convert into Multiply by Length mm inches 0.03937 mm feet 3.281 X 10-3 em inches 0.3937 feet -2 em 3.281 X 10 m feet 3.281 m yards 1.094 km miles 0.6214 Aree 2 square feet 10.76 m 2 square yards 1.196 m ha acres 2.471 km2 square mile 0.3861 Volume 3 cubic yards 1.308 m Speed m/s feet per second 3.281 Volume flow rete m3 ts cubic feet per second 35.31 Mass kg pound-mass 2.205 Force N pound-force 0.2248 N Ki logrem-force 0.1020 Pressure kPe pound-force per square inch 0.1450 Temperature oc OF 9/5 !then add 321 Concentration mg/1. parts per mi II ion -I .0 155 APPENDIX I GLOSSARY abandoned channel --A channel that was once an active or high-water chan- nel, but currently flows only during infrequent floods. active channel --A channel that contains flowing water during the ice-free season. active floodplain--The portion of a floodplain that is flooded frequently; it contains flowing channels, high-water channels, and adjacent bars, usually containing I ittle or no vegetation. aesthetics --An enjoyable sensation or a pleasurable state of mind, which has been instigated by the stimulus of an outside object, or it may be viewed as including action which wil I achieve the state of mind de- sired. This concept has a basic psychological element of individual learned response and a basic social element of conditioned social atti- tudes. Also, there can be ecological conditioning experience because the physical environment also affects the learning process of attitudes. algae --Primitive plants, one or many-eel led, usually aquatic and capable of elaborating the foodstuffs by photosynthesis. aliquot--A portion of a gravel removal area that is worked independently, often sequentially, from the other portions of the area. a I I uv i a I r i ver A river which has formed its channel by the process of aggradation, and the sediment by which it carries !except for the wash load) is similar to that in the bed. arctic--The north polar region bounded on the south by the boreal forest. 157 armor layer --A layer of sediment that is coarse relative to the material underlying it and is erosion resistant to frequently occurring floods; it may form naturally by the erosion of finer sediment, leaving coarser sediment in place or it may be placed by man to prevent erosion. aufeis --A~ !ce feature that is formed by water overflowing onto a surface, such as river ice or gravel deposits, and freezing, with subsequent layers formed by water overflowing onto the ice surface itself and freezing. backwater analysis --A hydraulic analysis, the purpose of which is to compute the water surface profile in a reach of channel with varying bed slope or cross-sectional shape, or both. bank--A comparatively steep side of a channel or floodplain formed by an erosional process; its top is often vegetated. bank-ful I discharge--Discharge corresponding to the stage at which the overflow plain begins to be flooded. bar--Anal luvial deposit or bank of sand, gravel, or other material, at the mouth of a stream or at any point in the stream flow. beaded stream--A smal I stream containing a series of deep pools intercon- nected by very smal I channels, located in areas underlain by permafrost. bed --The bottom of a watercourse. bed load Sand, si It, gravel or soi I and rock detritus carried· by a stream on, or immediately above its bed. bed load material --That part of the sediment load of a stream which is composed of particle sizes found in appreciable quantities in the shift- ing portions of the stream bed. 158 bed, moveble-A streem bed mede up of meteriels reedily trensporteble by the streem f I ow. bed, streem --The bottom of 11 streem below the low summer flow. breided river--A river conteining two or more interconnecting chennels seperated by unvegetated gravel bers, spersely vegeteted islends, end, occesionel ly, heevily vegeteted islends. Its floodplein is typicel ly wide end spersely vegeteted, end conteins numerous high-weter chennels. The laterel stebi I ity of these systems is quite low within the boun- deries of the ective floodplein. cerrying cepeclty, biological --The meximum everege number of e given orgen- ism thet cen be meinteined indefinitely, by the habitat, under a given regime !in this cese, f I owl • cerrying cepacity, discherge --The meximum rete of flow thet e chennel is capeble of pessing. chennel --A nature! or ertificiel weterwey of perceptible extent which periodically or continuously conteins moving weter. It has a definite bed end benks which serve to confine the weter. configuretion --The pettern of e river chennellsl es it would eppeer by looking verticel ly down et the weter. contour--A line of equel elevetion ebove e specified detum. cover, benk --Arees essocieted with or edjacent toe streem or river thet provide resting shelter end protection from predetors-e.g., undercut banks, overhenging vegetetion, accumuleted debris, and others. cover, fish--A more specific type of instreem cover, e.g., pools, boulders, weter depths, surfece turbulence, end others. 159 cover, instreem --Arees of shelter in e streem chennel thet provide equetic orgenisms protection from predetors ore piece in which to rest, or both, end conserve energy due to a reduction in the force of the cur- rent. cross section eree--The eree of e stream, chennel, or waterway opening, usually teken perpendicular to the streem centerline. current --The flowing of weter, or other fluid. Thet portion of e stream of weter which is moving with e velocity much greeter than the everege or in which the progress of the water is principally concentrated !not to be confused withe unit of measure, see velocity!. detum --Any numericel or geometrical quantity or set of such quantities which mey serve as a reference or base for other quentities. An egreed standard point or plene of stated elevation, noted by permanent bench merks on some solid immovable structure, from which elevetions are meas- ured, or to which they are referred. dewater --The dreining or removal of weter from an enclosure or channel. discherge --The rate of flow, or volume of water flowing in e given streem et e given piece and within a given period of time, expressed as cu ft per sec. dreinege area--The entire erea drained by e river or system of connecting streams such that alI streem flow originating in the area is discherged through a single outlet. dredge--Any method of removing gravel from ective channels. drift, invertebrete --The equatic or terrestriel invertebrates which heve been releesed from lbehevioral drift!, or heve been swept from (catas- trophic drift! the substrete, or have fa I len into the stream end move or fleet with the current. 160 duration curve--A curve which expresses the relation of alI the units of some item such as head and flow, arranged in order of magnitude along the ordinate, and time, frequently expressed in percentage, along the abscissa; a graphical representation of the number of times given quantities are equaled or exceeded during a certain period of record. erosion, stream bed --The scouring of material from the water channel and the cutting of the banks by running water. The cutting of the banks is also known as stream bank erosion. fines--The finer grained particles of a mass of soi I, sand, or gravel. The material, in hydraulic sluicing, that settles last to the bottom of a mass of water. flood--Any flow which exceeds the bank-ful I capacity of a stream or chan- nel and flows out on the floodplain; greater than bank-ful I discharge. floodplain--The relatively level land composed of primarily unconsolidated river deposits that is located adjacent to a river and is subject to flooding; it contains an active floodplain and sometimes contains an inactive floodplain or terracelsl, or both. flood probability--The probabi I ity of a flood of a given size being equaled or exceeded in a given period; a probabi I ity of I percent would be a 100-year flood, a probability of 10 percent would be a 10-year flood. flow--The movement of a stream of water or other mobile substances, or both, from place to place; discharge; total quantity carried by a stream. flow, base--That portion of the stream discharge which is derived from natural storage-i.e., groundwater outflow and the draining of large lakes and swamps or other sources outside the net rainfal I which creates the surface runoff; discharge sustained in a stream channel, 161 not e result of direct runoff end without the effects of regulation, diversion, or other works of man. Also cal led sustaining flow. flow, leminer --That type of flow in e stream of weter in which eech par- ticle moves in a direction perel lei to every other particle. flow, low--The lowest discharge recorded over e specified period of time. flow, low summer--The lowest flow durin~ c typical open-water season. flow, uniform--A flow in which the velocities ere the same In both magni- tude end direction from point to point. Uniform flow is possible only in e channel of constant cross section. flow, varied--Flow occurring in streams having e variable cross section or slope. When the discharge is constant, the velocity changes with each change of cross section end slope. fork length--The length of e (ish measured from the tip of the nose to the fork in the tai 1. freeze front --A surface thet may be stationery, which hes e temperature of 0°C and is warmer on one side of the surface end colder on the other. frequency curve --A curve of the frequency of occurrence of specific events. The event thet occurs most frequently is termed the mode. gege --A device for indicating or registering magnitude or position in spe- cific units, e.g., the elevation of e water surface or the velocity of flowing water. A steff graduated to indicate the elevation of a water surface. geomorphology --The study of the form end •evelopment of lendscepe fea- tures. 162 habitat --The place where a population of animals I ives and its sur- roundings, both I iving and non I iving; includes the provision of life requirements such as food and shelter. high-water channel --A channel that is dry most of the ice-free season, but contains flowing water during floods. hydraulics--The science dealing with the mechanical properties of fluids and their application to engineering; river hydraulics deals with mechanics of the conveyance of water in a natural watercourse. hydraulic depth--The average depth of water in a stream channel. It is equal to the cross-sectional area divided by the surface width. hydraulic geometry--Those measures of channel configuration, including depth, width, velocity, discharge, slope, and others. hydraulic radius --The cross-sectional area of a stream of water divided by the length of that part of its periphery in contact with its contain- ing channel; the ratio of area to wetted perimeter. hydrograph --A graph showing, for a given point on a stream, the discharge, stage, velocity, or another property of water with respect to time. hydrology--The study of the origin, distribution, and properties of water on or near the surface of the earth, ice-rich material --Permafrost material with a high water content in the form of ice, often taking the shape of a vertical wedge or a horizontal lens. impervious --A term applied to a material through which water cannot pass or through which water passes with great difficulty. 163 inactive floodplain--The portion of a floodplain that is flooded infre- quently; it may contain high-water and abandoned channels and is usually lightly to heavily vegetated. island--A heavily vegetated sediment deposit located between two channels. large river--A river with a drainage area greater than 1,000 km 2 and a mean annual flow channel top width greater than 100m. lateral bar--An unvegetated or I ightly vegetated sediment deposit located adjacent to a channel that is not associated with a meander. Manning's equation --In current usage, an empirical formula for the calcula- tion of discharge in a channel. The formula is usually written Q = 1.49 R 2/3 5 112 A. n mean flow--The average discharge at a given stream location computed for the period of record by dividing the total volume of flow by the number of days, months, or years in the specified period. mean water velocity The average velocity of water in a stream channel,. which is equal to the discharge in cubic feet per second divided by the cross-sectional area in square feet. For a specific point location, it is the velocity measured at 0.6 of the depth of the average of the velocities as measured at 0.2 and 0.8 of the depth. meander wave length --The average downval ley distance of two meanders. meandering river A river winding back and forth within the floodplain. The meandering channel shifts downval ley by a regular pattern of ero- sion and deposition. Few islands are found in this type of river and gravel deosits typically are found on the point bars at the insides of meanders. 164 medium river --A river with a drainage area greater than 100 km 2 but less than 1,000 km 2 and a mean annual flow channel top width greater than 15 m but less than 100 m. microhabitat--Localized and more specialized areas within a community or habitat type, uti I ized by organisms for specific purposes or events, or both. Expresses the more specific and functional aspects of habitat and cover that allows the effective use of larger areas !aquatic and ter- restrial l in maximizing the productive capacity of the habitat. !See cover types, habitat). mid-channel bar--An unvegetated or lightly vegetated sediment deposit lo- cated between two channels. parameter --A variable in a mathematical function which, for each of its particular values, defines other variables in the function. permafrost --Perennially frozen ground. pit excavation--A method of removing gravel, frequently from below over- burden, in a manner that results in a permanently flooded area. Gravels are usually extracted using drag I ines or backhoes. point bar An unvegetated sediment deposit located adjacent to the inside edge of a channel in a meander bend. pool --A body of water or portion of a stream that is deep and quiet rela- tive to the main current. pool, plunge--A pool, basin, or hole scoured out by fal I ing water at the base of a waterfall. profile--In open channel hydraulics, it is the water or bed surface ele- vation graphed aganist channel distance. 165 reach --A comparatively short length of a stream, channel, or shore. regional analysis --A hydrologic analysis, ihe purpose of which is to esti- mate hydrologic parameters of a river by use of measured values of the same parameters at other rivers within a selected region. riffle--A shallow rapids in an open stream, where the water surface is broken into waves by obstructions wholly or partly submerged. riparian--Pertaining to anything connected with or adjacent to the banks of a stream or other body of water. riparian vegetation--Vegetation bordering floodplains and occurring within floodplains. riprap-Large sediments or angular rock used as an artificial armor layer. river regime--A state of equilibrium attained by a river in response to the average water and sediment loads it receives. run--A stretch of relatively deep fast flowing water, with the surface essentially nonturbulent. scour--The removal of sediments by running water, usually associated with remov~l from the channel bed or floodplain surface. scrape-A method of removing floodplain gravels from surface deposits using tractors or scrapers. sediment discharge--The volumetric rate of sediment transfer past a spe- cific river cross section. sinuous river --Sinuous channels are similar to meandering channels with a less pronounced winding pattern. The channel may contain smaller 166 point bars and have less tendency for downval ley shifting. The channels are more stable with respect to lateral shifting. sinuousity --A measure of the amount of winding of a river within its flood- plain; expressed as a ratio of the river channel length to the corres- ponding val ley length. slope--The inclination or gradient from the horizontal of a line or sur- ~face. The degree of inc I ination is usually expressed as a ratio, such as I :25, indicating one unit rise in 25 units of horizontal distance. smal I river -A river with a drainage area less than 100 km 2 and a mean annual flow channel top width of less than 15m. split river--A river having numerous islands dividing the flow into two channels. The islands and banks are usually heavily vegetated and stable. The channels tend to be narrower and deeper and the floodplain narrower than for a braided system. stage--The elevation of a water surface above or below an established datum or reference. standing crop --The abundance or total weight of organisms existing in an area at a given time. straight river The thalweg of a straight river typically winds back and forth within the channel. Gravel bars form opposite where the thalweg approaches the side of the channel. These gravel bars may not be ex- posed during low flow. Banks of straight systems typically are stable and floodplains are usually narrow. These river systems are considered to be an unusual configuration in transition to some other configura- tion. subarctic--The boreal forest region. 167 suspended load --The portion of stream load moving in suspension and made up of particles having such density of grain size as to permit movement far above and for a long distance out of contact with the stream bed. The particles are held in suspension by the upward components of turbu- lent currents or by colloidal suspension. tal ik --A zone of unfrozen material within an area of permafrost. terrace--An abandoned floodplain formed as a result of stream degradation and that is expected to be inundated only by infrequent flood events. thalweg--The line following the lowest part of a val ley, whether under water or not; also usually the I ine following the deepest part or middle of the bed or channel of a river or stream. thermokarst --Landforms that appear as depressions in the ground surface or cavities beneath the ground surface which result from the thaw of ice-rich permafrost material. top width--The width of the effective area of flow across a stream chan- nel. velocity--The time rate of motion; the distance traveled divided by the time required to travel that distance. wash load--In a stream system, the relatively fine material in near-perman- ent suspension, which is transported entirely through the system, without deposition. That part of the sediment load of a stream which is composed of particle sizes smaller than those found in appreciable quantities in the shifting portions of the stream bed. water quality--A term used to describe the chemical, physical, and biolog- ical characteristics of water in reference to its suitability for a particular use. 168 wetted perimeter --The length of the wetted contact between the stream of flowing water and its containing channel, measured in a plene at right angles to the direction of flow. wildlife--AI I living things that are neither human nor domesticated; most often restricted to wildlife species other than fish and invertebrates. 169 CD " :J " .... .. 3 "C " .... .. .... 0 0' .. c Ul .. c. ~ .... :T 3 " .... -, X .... " 0' .. Ul Ul .. .. "C "' "' .. "' Ul ;u N < .. .. -, 0 n "' " -· ........ -· .. 0 :J :>-n U> :TU> " 0 => n :J -· .. " -.... .. c. -i -< "C .. 0 - c. .. "C 0 Ul .... Small Medium Large Active floodplain Inactive floodplain Terrace Active channel High-water channel Abandoned channel Bed Point bar Lateral bar Mid-channel bar Inside meander Outside meander Vegetated island Vegetated bank 50272-101 REPORT DOCUMENTATION !-'~REPORT NO. I~ 3. Recipient"s Accession No. PAGE FWS/OBS-80/09 4. Title and Subtitle 5. Report Date June 1980, Pub. dete GRAVEL REMOVAL STUDIES IN ARCTIC AND SUBARCTIC FLOODPLAINS IN ALASKA-GUIDELINES MANUAL .. N/A 7. Author(s) 8. Performinc Orpnlzatlon Rept. No. WOODWARD-CLYDE CONSULTANTS 9. Performln& O .... nlntlon Name and Address 10. Project/Task/Work Unit No. Woodwerd-Ciyde Consultents 11. Contnct(C) or Grant(G) No. 4791 Business Perk Blvd., Suite f1 Anchorege, Aleske 99503 (C) FWS 14-16-0008-970 (G) 12. SponsorinK Ora:anlutlon Name and Address 13. Type of Report & Period Covered U. S. Fish end Wild! ife Service Fine! Report 1011 Eest Tudor Roed 1975 -1980 Anchorege, Aleske 99503 14. 15. Supplementary Notes This report is pert of Interagency Energy -Environment Reseerch end Development Progrem of the Office of Reseerch end Development, U.S. Environmentel Protection Agency -------------·· 16. Abstract (Limit: 200 wordS) A 5-yeer investigetion of the effects of floodplain grevel mining on .the physicel end biologicel charecteristics ·of river systems in arctic end subarctic Aleske is described. Twenty-five sites were studied within four geogrephic regions. The sites were selected such thet within eech of the regions the group of sites exhibited e wide renge of river end mining cherecteristics. The field date collection progrem covered the mejor disciplines of hydrology/hydreul ics, equetic biology, weter quel ity, end terrestriel biology. In eddition, geotechnicel _engineering, end aesthe- tics site reviews were conducted. A wide renge of megnitude end type of physical end bio!ogicel changes were observed in response to mining ectivity. Little chenge wes observed et some sites, whereas other sites exhibited changes in chennel morphology, hydraulics, sedimentetion, ice regime, equatic habitet, water quality, benthic mecroinvertebretes, fish uti lizetion, vegetetion, soil cherecteristics, end bird and memmel usege. Two mejor products of the project ere a Technicel Report which synthesizes and evaluates the date collected at the sites, end 11 Guide! ines Menual thet eids the user in developing plans end opereting materiel sites to minimize environmentel effects. . 17. Document Analysis a. Descriptors Greve! Remove!, Alaske, Arctic, Subarctic, Floodpleins, Streams, Scraping, Pit Excevation, Environmental impects, Hydrology-Hydreul ics, Aquetic Biology, Terrestriel Ecology, Water Quel ity, Aesthetics, Geotechnicel Engineering, Site Selection, Site Design. b. Identifiers/Open-Ended Terms c. COSATI Field/Group lL Availability Statement 1!. Security Class (This Report) 21. No. of P88H Unclessified 169 Releese unlimited -- 20. rrnrl,i'~"i'IY'k•J'" .. ' 22. Price (See ANSI-z39.18) s .. Instructions on Reverse OPTIONAL FORII 272 (4-7n (Formerly NTIS-35) Department of Commerce • *U.S. GOVERNMENT PRINTING OFFICE: 198Q--699-278 REGIONAL OFFICE BIOLOGICAL SERVICES TEAMS Region 1 Team Leader U.S. Fish and Wildlife Service Lloyd 500 Building, Suite 1692 500 N.E. Multnomah Street Portland, Oregon 97232 FTS: 429-6154 COMM: (503) 231-6154 Region2 Team Leader U.S. Fish and Wildlife Service P.O. Box 1306 Albuquerque, New Mexico 87103 FTS: 474-2971 COMM: (505) 766-1914 Region3 Team Leader U.S. Fish and Wildlife Service Federal Building, Fort Snelling Twin Cities, Minnesota 55111 FTS: 725-3593 . COMM: (612) 725-3510 Region4 Team Leader U.S. Fish and Wildlife Service 17 Executive Park Drive, N.W. P.O. Box 95067 Atlanta, Georgia 30347 FTS: 257-4457 COMM: (404) 881-4457 Regions Team Leader U.S. Fish and Wildlife Service One Gateway Center Suite700 Newton Corner, Massachusetts 02158 FTS: 829-9217 COMM: (617)965-5100, Ext. 217 Region6 Team Leader U.S. Fish and Wildlife Service P.O. Box 25486 Denver Federal Center Denver, Colorado 80225 FTS: 234-5588 COMM: (303) 234-5588 Alaska Area Office Team Leader U.S. Fish and Wildlife Service 1011 E. Tudor Road Anchorage, Alaska 99503 FTS: 3~150 ask for COM M: (907) 276-3800