S-10-0164 Attachment 13 Eagle Lake WWTP Leak Location Survey and Report.pdf

LEAK LOCATION SERVICES, INC.

16124 UNIVERSITY OAK ! SAN ANTONIO, TEXAS 78249 ! (210) 408-1241 / FAX (210) 408-1242

Since 1992 www.llsi.com results@llsi.com

November 11, 2009

Mr. Jeffrey M. Greis USDA Forest Service 2550 Riverside Drive Susanville, CA 96130 e-mail: jmgreis@fs.fed.us

Subject: Report for "Leak Location Surveys of Four Wastewater Ponds Located Near Eagle Lake, California ” LLSI Proposal 1302

Dear Mr. Greis:

On September 22, through September 25, 2009, Phillip Gatesuwan and Thane Hefley of Leak Location Services Inc. (LLSI) conducted geomembrane leak location surveys on four wastewater ponds near Eagle Lake, California. The ponds are lined with a single 40-mil Hypalon geomembrane and have 3H:1V side slopes. The Evaporation Pond # 3 did not have water in it, so it could not be tested. Primary Pond #1 is circular and has a radius of 81.5 feet. Primary Pond #2 has floor dimensions of 100 feet by 160 feet, and Evaporation Ponds #1 and # 2 have floor dimensions of 240 feet by 345 feet. This report documents the results of the surveys.

I. RESULTS

A. Primary Pond #1

Primary Pond #1 evidently did not have geomembrane on the floor area, so only the slopes were surveyed for leaks. As the probe was towed across the pond, a very strong signal was measured 30 feet from the perimeter, but no signal was obtained beyond that point. It was surmised that the floor did not have a geomembrane and the large signal was caused by battens that fasten the geomembrane to the floor or by the probe moving across the edge of the geomembrane. So a strategy was developed to keep the current injection electrode near the survey area and to survey only the slopes. No leak signals were detected, but the effectiveness of the leak location survey was probably compromised greatly because of the current flowing to the unlined bottom.

B. Primary Pond # 2

Sixteen leaks were found in the geomembrane liner of Primary Pond #2. Table 1 lists the locations of the leaks. Figure 1 shows the approximate locations of the leaks. The locations of the leaks are referenced to survey lines marked in feet on the geomembrane near the top of the slope.

The distances along the survey line to the leaks were also marked on the geomembrane.

USDA Forest Service Page 2 of 8 November 11, 2009 LLSI Project 1302

Table 1. Locations of Leaks in Primary Pond # 2

LEAK LOCATION

1 Line 0, 70 feet from mark on the north east side slope

2 Line -2.5, 20 feet from mark on the north east side slope

3 Line 12.5, 78 feet from mark on the east side slope

4 Line 10, 12 feet from mark on the east side slope

5 Line 72.5, 10 feet from mark on the east side slope

6 Line 97.5, 7 feet from mark on the east side slope

7 Line 97.5, 72 feet from mark on the east side slope

8 Line 102.5, 70 feet from mark on the east side slope

9 Line 107.5, 10 feet from mark on the east side slope

10 Line 125, 10 feet from mark on the east side slope

11 Line 197.5, 20 feet from mark on the south east side slope

12 Line 202.5, 30 feet from mark on the south east side slope

13 On lone 190, 10 feet from mark on the west side slope

14 Line 80, 10 feet from mark on the west side slope

15 Line 35, 10 feet from mark on the west side slope

16 Line 22.5, 14 feet from mark on the west side slope

USDA Forest Service Page 3 of 8

FIGURE 1. APPROXIMATE LOCATIONS OF THE LEAKS FOUND IN PRIMARY POND # 2

C. Evaporation Pond #1

Sixteen leaks were found in the geomembrane liner of Evaporation Pond #1. Table 2 lists the locations of the leaks. Figure 2 shows the approximate locations of the leaks. The locations of the leaks are referenced to survey lines marked in feet on the geomembrane near the top of the slope. The distances along the survey line to the leaks were also marked on the geomembrane.

USDA Forest Service Page 4 of 8

Table 2. Locations of Leaks in Evaporation Pond #1

LEAK LOCATION

1 Line 0, 230 feet from mark on the north side slope

2 Line 10, 39 feet from mark on the north side slope

3 Line 12.5, 248 feet from mark on the north side slope

4 Line 32.5, 20 feet from mark on the north side slope

5 Line 97.5, 227 feet from mark on the north side slope

6 Line 127.5, 25 feet from mark on the north side slope

7 Line 132.5, 25 feet from mark on the north side slope

8 Line 237.5, 255 feet from mark on the north side slope

9 Line 267.5, 20 feet from mark on the north side slope

10 Line 325, 262 feet from mark on the north side slope

11 Line 360, 100 feet from mark on the north side slope

12 Line 360, 30 feet from mark on the north side slope

13 Line 265, 7 feet from mark on the south side slope

14 Line 280, 8 feet from mark on the south side slope

15 Line 295, 6 feet from mark on the south side slope

16 Line 302.5, 6 feet from mark on the south side slope

USDA Forest Service Page 5 of 8

FIGURE 2. APPROXIMATE LOCATIONS OF THE LEAKS FOUND IN

EVAPORATION POND #1

D. Evaporation Pond #2

Thirty-two leaks were found in the geomembrane liner of Evaporation Pond #2.

Table 3 lists the locations of the leaks. Figure 3 shows the approximate locations of the leaks. The locations of the leaks are referenced to survey lines marked in feet on the geomembrane near the top of the slope. The distances along the survey line to the leaks were also marked on the geomembrane.

Table 3. Locations of Leaks in Evaporation Pond #2

LEAK LOCATION

1 Line 2.5, 215 feet from mark on the south side slope

2 Line 5, 38 feet from mark on the south side slope

3 Line 15, 252 feet from mark on the south side slope

4 Line 37.5, 20 feet from mark on the south side slope

5 Line 112,5, 22 feet from mark on the south side slope

6 Line 137.5, 120 feet from mark on the south side slope

USDA Forest Service Page 6 of 8

LEAK LOCATION

7 Line 210, 208 feet from mark on the south side slope

8 Line 220, 216 feet from mark on the south side slope

9 Line 272.5, 24 feet from mark on the south side slope

10 Line 320, 162 feet from mark on the south side slope

11 Line 322.5, 24 feet from mark on the south side slope

12 Line 330, 22 feet from mark on the south side slope

13 Line 335, 21 feet from mark on the south side slope

14 Line 340, 23 feet from mark on the south side slope

15 Line 345, 26 feet from mark on the south side slope

16 Line, 347.5, 112 feet from mark on the south side slope

17 Line 347.5, 22 feet from mark on the south side slope

18 Line 365, 67 feet from mark on the south side slope

19 5 feet from mark on the east side slope

20 7 feet from mark on the east side slope

21 Line 325, 5 feet from mark on the east side slope

22 Line 250, 5 feet from mark on the north side slope

23 Line 212.5, 5 feet from mark on the north side slope

24 Line 205, 4 feet from mark on the north side slope

25 Line 167.5, 8 feet from mark on the north side slope

26 Line 140, 4 feet from mark on the north side slope

27 Line 122.5, 8 feet from mark on the north side slope

28 Line 10, 8 feet from mark on the north side slope

29 4 feet from mark on the west side slope

30 8 feet from mark on the west side slope

31 2 feet from mark on the west side slope

32 8 feet from mark on the west side slope

USDA Forest Service Page 7 of 8

FIGURE 3. APPROXIMATE LOCATIONS OF THE LEAKS FOUND IN

EVAPORATION POND #2

II. TECHNIQUE

A. General

The electrical leak location method detects electrical paths through the liner caused by water in the leaks of the liner. A voltage is connected to one electrode placed in a conducting media covering the liner and another electrode placed in contact with earth ground. Electrical current flowing through the leaks in the liner produces localized anomalous areas of high current density near the leaks. These areas are located by making electrical potential measurement scans throughout the flooded area.

B. Calibration

The leak location survey equipment was tested for proper operation using an artificial leak per ASTM D7007. A simulated leak was constructed by placing a 0.06 inch hole in a plastic container with a thickness approximating the thickness of the liner. An insulated wire with a stripped end will enter the container through a sealed insulating penetration. The other end of the wire is connected to ground. The container is filled with water from the pond and submerged in the pond. The leak detection distance was approximately 3 feet.

USDA Forest Service Page 8 of 8

C. Towed-Probe Survey

A towed-probe survey was used for the survey of the ponds. This method is to tow a remote sensor across the shorter dimension of the pond while survey personnel stand at the top of the side-slopes on opposite banks of the pond. The sensor is towed down the side-slope across the bottom and then back up the opposite side-slope along the established survey lines. The probe and cable are then moved to the next survey line and the process reversed. The survey lines are spaced approximately 2.5 feet apart and are established by placing temporary marks on the liner side-slope near where the survey operators will stand.

When a leak is located, the position of the leak is determined by measuring the distance to the sensor when the sensor is at the leak. However, because the probe can only be maneuvered along the survey line, and because of the tolerances in the measurement accuracy, the positioning accuracy for located leaks is anticipated to be about three-feet. When the water is removed for repair, the leak must be located visually by the leak repair crew using the distance marks provided to guide the repair personnel.

If there are any questions about the leak location surveys or this report, please contact us at

(210) 408-1241. We appreciate this opportunity to have been of service to U.S. Forest Service on this important service requirement.

Very truly yours, Herman Flores Project Manager

Approved by:

Glenn T. Darilek Principal Engineer