HomeMy WebLinkAboutFourth of July Creek Hydroelectric Project Hydrology Report - Jun 2010 - REF Grant 21954201503 WEST 33RD AVENUE, ANCHORAGE, ALASKA 99503
PHONE: (907) 258-2420 FAX: (907) 258-2419Independence Power, LLC
M EMORANDUM
DATE: JUNE 2, 2010
SUBJECT: FOURTH OF JULY CREEK HYDROLOGY – PROGRESS REPORT
TO: PROJECT FILE
FROM: JOEL GROVES – PROJECT MANAGER
BACKGROUND:
Flooding in late July 2009 scoured the stream bed at the powerhouse site gauging station on
Fourth of July Creek, invalidating the stage-discharge rating curve developed in 2008-2009.
This flood event also damaged the stream gauge installation. The extent of scour and flood
damage was not characterized until a site visit in December 2009.
CORRECTIVE ACTIONS:
1. In March 2010, the stream gauge was relocated to a more sheltered location to reduce the
likelihood of future damage to the gauge. The relocated gauge is in the same pool as the
original gauge.
2. In March 2010, a second gauge was installed approximately 100 yards downstream of the
original gauge. This gauge will serve as a backup gauge to reduce the potential for loss of
data.
3. Additional flow measurements have been conducted to establish new rating curves for both
powerhouse site gauging stations.
DATA:
Flow measurements have been conducted to develop rating curves over the range of proposed
project flows at both gauging stations.
1. Discharge data from September 2008 through May 2010 is presented on Page 2.
2. The current (2009-2010) rating curves for both stations and the 2008-2009 curve for the
upper powerhouse station are presented on Page 3.
3. Flow measurements used to develop the rating curves are tabulated on Page 4.
FOURTH OF JULY CREEK - DISCHARGE DATA0501001502002503003504009/1/08 10/27/08 12/22/08 2/16/09 4/13/09 6/8/09 8/3/09 9/28/09 11/23/09 1/18/10 3/15/10 5/10/10DATEDISCHARGE AT INTAKE SITE (CFS)Measured DischargeExpected Discharge at Intake (Based on Hydrology Model)2008-09 Calculated Flow at Intake2009-10 PROVISIONAL Calculated Flow at Intake (UPPER PH GAUGE)2009-10 PROVISIONAL Calculated Flow at Intake (LOWER PH GAUGE)NOTE: Calculated flows are based on the stage recorded at the gauging station and the stage-discharge curve(s) for each gauge. Flows are scaled by basin area to the proposed intake site.INDEPENDENCE POWER, LLC - JUNE 2010
RATING CURVES FOR POWERHOUSE SITE GAUGING STATIONS2008-09 Rating Curve - Upper PH Stationy = 16.109x3 + 151.16x2 + 503.93x + 601.4R2 = 12009-10 Rating Curve - Upper PH Stationy = 39.47x3 + 371.81x2 + 1203.8x + 1347R2 = 0.99912009-10 Rating Curve - Lower PH Stationy = 43.124x2 + 598.55x + 2080.8R2 = 1020406080100120140160-7.50 -6.50 -5.50 -4.50 -3.50 -2.50 -1.50Stage (ft)Discharge (cfs)2008-09 Measurements (Upper PH Station)2009-10 Measurements (Upper PH Station)2009-10 Measurements (Lower PH Station)Poly. (2008-09 Measurements (Upper PH Station))Poly. (2009-10 Measurements (Upper PH Station))Poly. (2009-10 Measurements (Lower PH Station))INDEPENDENCE POWER, LLC - JUNE 2010
FOURTH OF JULY CREEK HYDROLOGY STUDY
STAGE - DISCHARGE MEASUREMENTS
Date/Time
Stage (ft, Upper PH
Site Gauging
Station)
Stage (ft, Lower PH
Site Gauging
Station)
Measured
Discharge (cfs)Notes
9/26/08 15:00 -1.58 -119
12/4/08 15:45 -2.92 -17.7
3/27/09 13:20 -3.24 -7.5
4/9/09 12:15 -3.27 -6.6
4/23/09 19:55 -3.16 -10.2
5/5/09 17:30 -2.23 -50.8 pre 7/09 flood
12/3/09 16:05 -2.45 -47.7 post 7/09 flood
3/31/10 17:15 -3.20 -6.58 9.6
4/25/10 18:05 -2.99 -6.42 15.3
5/1/10 16:30 -2.64 -6.07 36.6
5/29/2010 14:45 -1.85 -5.15 142.8
INDEPENDENCE POWER, LLC - 6/2/2010 S-D data, _4thJulyGauging.xls