HomeMy WebLinkAboutAkutan geothermal report Appendix E 2014
Appendix E
Quarry Evaluation for the Geothermal Road Project
Quarry Evaluation for the
Geothermal Road Project
Akutan, AK
Prepared by
Quarry Site
Mead & Hunt, Inc. 1345B North Road Green Bay, Wisconsin 54313
920 496 0500 fax 920 496 0576 www.meadhunt.com
Technical Memorandum
To: Ray Mann
RMA Consulting Group
From: Jim Botz, P.E.
Reviewed by: Kari Nichols, P.E.
Date: January 14, 2014
Subject: Quarry Evaluation for the Geothermal Road Project, Akutan, AK
1.0 Introduction and Background
A Geothermal Road is being designed to provide access to the geothermal site from the Akutan
Harbor. It will be approximately 4.7 miles long and will extend from the Akutan Boat Harbor on
the north side of the valley to the production well site. As planned, the road will be 20 feet wide
with a gravel surface course measuring 6 to 12 inches in thickness. Based on these design
dimensions, it is estimated that 14,000 cubic yards of high quality gravel surface course will be
required for the project. The potential quarry site nearby was identified initially as a source for
the materials. Once developed, it was expected that the quarry would also be a source for
construction aggregates, such as concrete, in conjunction with the geothermal plant
construction and other City of Akutan projects. This memorandum summarizes the explorations
and findings related to the potential quarry site.
An early investigative study for the harbor development performed by Peratrovich & Nottingham,
Inc. (1982) identified three possible quarry sites for the production of rip rap and crushed rock.
The largest site measured two acres and was located on the north side of the valley at the head
of the bay. This site is depicted in Figure 1 (Attachment A). It was estimated that as much as
290,000 cubic yards of material could be generated from this site. Due to its proximity and easy
access to the Geothermal Road project, this site was selected for further exploration and
evaluation.
2.0 Field Exploration
To begin the evaluation of the quality of the rock source, three rock core borings were planned
to be drilled at the base of the hillside. The borings were planned to be drilled at a 30 degree
angle from vertical to a depth of 60 feet. A BQ rock core (1.43 inches in diameter) was selected
as the most suitable size core for the drilling equipment that could be mobilized to the site.
Technical Memorandum
RMA Consulting Group
January 14, 2014
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The City of Akutan retained Denali Drilling of Anchorage, Alaska to perform the work. Denali
Drilling mobilized a Geoprobe track drill rig to the quarry site on September 5, 2013. Three
drilling locations were identified at the site by Jim Botz (Mead & Hunt) and Jason Love (Denali
Drilling). Drilling began at the easternmost location (C-1) close to Whale Bone Creek, the
source for drilling water (see Attachment A). Over a period of four days, Denali Drilling was only
able to advance the boring to a depth of 29.5 feet. During that time, Denali Drilling was plagued
with numerous equipment breakdowns and an inability to get replacement parts on a timely
basis. Due to budget constraints, the quarry exploration program was terminated September
14, 2013. At that time, only one boring was partially completed.
3.0 Exploration and Testing Results
The results of Boring C-1 are summarized on the attached boring log (Attachment B). The
boring encountered five feet of overburden soils before encountering bedrock. The overburden
soils consisted of a brown silty sand. A dark gray Andesite was encountered after the initial
overburden soils that extended to the termination depth of the boring. The Andesite was
medium grained, hard, and thin-to-medium bedded.
The rock cores were evaluated for overall quality by computing the Rock Quality Designation
(RQD), a standard first step for evaluating rock core samples. This procedure simply totals all
core lengths of greater than 4 inches and divides that total by the total length of the core run. A
higher percentage RQD indicates a higher rock quality. For Boring C-1, the quality of rock
tended to increase with depth as indicated by RQDs, increasing from 23% (very poor quality) at
6 feet up to 87% (good quality) at 25 feet into the formation. The boring was drilled at an angle
of 45 degrees and all depths in the boring log reference the actual length of boring rather than
the vertical or horizontal distances. A photographic log of the cores is included as Attachment C.
Next, the rock core was submitted to the AECOM test laboratory in Green Bay, Wisconsin for
rock quality testing on December 20, 2013, where Los Angeles Abrasion (LA Abrasion) and
Sodium Sulfate Soundness tests were performed on the rock core sample. The LA Abrasion
test indicates a rock’s ability to resist degradation under repeated traffic loadings. The Sodium
Sulfate Soundness test indicates a rock’s ability to resist the forces of weathering and simulates
the action of freezing water. The results of these tests are included as Attachment D.
The test results failed to meet the minimum standards for durability in both cases. The standard
set by the Alaska Department of Transportation and Public Facilities (DOT&PF) for the LA
Abrasion test is a maximum particle size loss of 45%. The Akutan rock core samples had a
particle size loss of 52.5%. The Sodium Sulfate Soundness test had a particle size loss of
Technical Memorandum
RMA Consulting Group
January 14, 2014
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71.2% compared to a required DOT&PF maximum of 12%. A further qualitative evaluation of
the Andesite was made by allowing the rock to be saturated in water for a period of five days.
After five days, the rock core sample exhibited some loss in strength which further documented
the Andesite’s poor durability properties.
The rock available from the proposed quarry site is a very poor-quality material and is not
recommended as a source for the gravel surface course for the Geothermal Road project. The
rock material will not hold up well to the harsh weather of Akutan and will not perform well as a
base course or concrete aggregate. It is unlikely that other similar rock source locations at the
head of the bay will produce a rock of any better quality.
4.0 Recommendations
Although there may be some opportunity to use blasted rock from the cut through the saddle
about a mile west of the harbor, the initial road construction from the harbor to the saddle will
need to use gravel surface course that is imported to the site. This imported material will likely
need to be sourced from one of the two operating quarries in Dutch Harbor. Both of these
quarries produce gravel material from granite in compliance with DOT&PF requirements for
durability.
Once the project reaches the saddle, a large volume of blast rock will be produced from the cut
through the saddle. Although initial conversations with area experts suggest that it is unlikely,
this material may be of better quality. The blast rock from the saddle location can most certainly
be used for general rock fills along the road. Further exploration and testing of that rock source
would be required to evaluate that material prior to its use as construction aggregates on the
project. The blast rock material testing should be undertaken during the final design phase of
the project.
Attachments:
A. Figure 1: Quarry Site
B. Boring Log of C-1
C. Photographs of Rock Core
D. Laboratory Test Results
Attachment A: Figure 1: Quarry Site
Attachment B: Boring Log of C-1
LOG OF BORING NO.:
SITE LOCATION:
SURFACE ELEVATION:
ɣ= DRY DENSITY, PCF WC - WATER CONTENT, %
N = BLOWS PER FOOT Qp = CALIBRATED PENETROMETER, TSF
Test results:
LA Abrasion: 52% loss
Sodium Sulfate Soundness: 71% loss
29.5
Run 3: Rec. = 93%
RQD = 28%
Run 5:Rec. = 93%
RQD = 31%
Run 6:Rec. = 100%
RQD = 69%
14.5
Run 7:Rec. = 100%
RQD = 87%
One 3 in. zone of gravel size particles
Run 4: Rec. = 85%, RQD = 33%
24.5
Run 1:Rec. = 100%
RQD = 0%Dark gray Andesite - medium grained - hard - very
slightly weathered - thin to medium bedded
9.5
Run 2: Rec. = 80%
RQD = 23%
4 zones 1 to 6 in. of gravel size particles
5.0
5.6
13.5
Brown silty sand
30 End of boring
19.5
10
C-1
Akutan, AK
+8 (estimated)
WATER LEVEL MEASUREMENTS
DRILLING DATES: September 5, 2013 to September 8, 2013
DRILLING METHOD(S): BQ (1.69" diameter) wireline core
DESCRIPTION OF MATERIAL
Run
Lengths
(FT)
LABORATORY AND CORE
RESULTS
25
15
20
DATE DEPTH ELEVATIONTIME
DRILLING FIRM: Denali Drilling
3054300-100001.0 / 000004 / 000006
Geothermal Road
PROJECT NO.:
RMA Consulting Group
CLIENT:
PROJECT NAME:
DEPTH (FT)
5
Attachment C: Photographs of Rock Core
Photograph 1: C‐1 Run 1 and 2
Photograph 2: C‐1 Run 3 and 4
Photograph 3: C‐1 Run 3 and 4
Photograph 4: C‐1 Run 6
Photograph 5: C‐1 Run 7
Photograph 6: Field photograph of core samples.
Attachment D: Laboratory Test Results
LA Abrasion Test Data Sheet - ASTM C 131
Project No.:
Job No.:
Date:
Report No.:
Architect/
Engineer:Contractor:
Project:Source:
Report Test of:
Mechanical Analysis Gradings for Test
Sieve Size Weight Cumulative Weight %%Sieve Size Weight in Grams
or No.Retained Retained Retained Passing or No.A B C D
3-Inch 3-Inch
1 1/2-Inch 1 1/2-Inch 1250
1-Inch 1-Inch 1250
3/4-Inch 3/4-Inch 1250 2500
1/2-Inch 1/2-Inch 1250 2500
3/8 Inch 3/8 Inch 2500
1/4-Inch 1/4-Inch 2500
No. 4 No. 4
No. 8 No. 8 5000
Pan Abrasion Data (Grading):B
Total Total Sample Weight (Grams) (A)5000
Charge of Spheres Dry Weight Washed On
Grading No. of
Spheres
Spec.
(grams)
Weight As Run
(grams)Passing
A 12 5000 ± 25 Percent Wear
B 11 4584 ± 25 4595 Dry Weight Washed On 2376
C 8 3330 ± 20 Passing 2624
D 6 2500 ± 15 Percent Wear 52.5 %
Remarks:Specifications Requirements
Abrasion Loss By Weight:45 % Max
Abrasion Loss, This Sample:52.5
This sample DOES [ ] DOES NOT [X] meet specification
Tested By:RJP Computed By:RJP Checked By:
Geothermal Road Quarry C-1, Akutan, Alaska
Crushed Rock Core
60249529
12/23/2013
C-1
Mead & Hunt, Inc.
(C500/Ax100)
(C100/Ax100)
(C100=A-B100)
(B100)
(C500=A-B500)
(B500)
K:\PROJECTS\60249529\60249529_LA Abrasion Test Data Sheet (Mead and Hunt).xls
Analysis of Aggregates - Soundness of Aggregate Test Data Sheet
ASTM C 88, 5 Cycles
Project No.:Date:
Project:Report No.:
Architect / Engineer:Contractor:
Source:
Report of Tests of:
Sieve Size
Passing Retained
Grading of Original
Sample %
Weight of Fraction
Before Test
Actual
% Loss
Weighted Average
Loss
Soundness Test of Coarse Aggregate
2-1/2 in.1-1/2 in.
1-1/2 in.3/4 in.
3/4 in.3/8 in.76.9 1000.4 65.4 50.3
3/8 in.No. 4 23.1 300.1 90.6 20.9
Totals 100.0 71.2
Sieve Size
Passing Retained
Grading of Original
Sample %
Weight of Fraction
Before Test
Actual
% Loss
Weighted Average
Loss
Soundness Test of Fine Aggregate
No. 100
No. 50 No. 100
No. 30 No. 50
No. 16 No. 30
No. 8 No. 16
No. 4 No. 8
3/8 in.No. 4
Totals
Specification Requirements
Coarse Aggregate Fine Aggregate
Sodium Sulfate Loss by Weight 12.0 % Max Magnesium Sulfate
Sodium Sulfate Loss by Weight
Loss by this Sample 71.2 % Loss by this Sample
This sample DOES [ ] DOES NOT [X] meet the specification This sample DOES [ ] DOES NOT [ ] meet the specification
Tested By:Checked By:RJP RJP
Crushed Rock Core
12/23/13
C-1A
60249529
Geothermal Road Quarry
Mead & Hunt, Inc.
C-1, Akutan, Alaska
K:\PROJECTS\60249529\60249529_Soundness of Aggregate (Mead and Hunt).xls