SECTION 01660
WATER TEST FOR CONCRETE TANKS
PART 1 GENERAL
1.1 DESCRIPTION
A. This section includes leakage testing for all new liquid holding concrete tanks.
1.2 TEST CONDITIONS
A. Conduct test prior to backfilling and prior to coating tank.
B. Test shall not be started prior to concrete obtaining its 28 day strength.
C. Water for testing: Treated plant effluent is available for use by the Contractor. Contractor shall provide temporary pumping and piping facilities to transport water. City water (W1) and / or non-potable water (W2) is available for use by the Contractor. Contractor shall pay costs of W1 and W2 water directly to the Owner. Contractor shall provide temporary pumping and piping facilities to transport water as required. Disposal of water used in testing shall be the Contractor's responsibility.
1.3 TEST CRITERION
A. Water Leakage Tests - All Water-Holding Structures:
1. All new water-holding structures shall be subjected to leakage tests after the concrete has been cured and obtained its design strength, and before backfill, brick facing, or other work that will cover the exposed faces of the walls is begun.
2. All basins to be subjected to leakage tests shall be filled with water to the normal liquid level line. After the basin has been kept full for 48 hours, it will be assumed for the purposes of the test that the absorption of moisture by the concrete in the basin is complete. All valves and gates to the structure shall then be closed and the change in water surface measured for a 24-hour period.
3. During the test period, all exposed portions of the structure shall be examined and all visible leaks or damp spots shall be marked; such leaks or damp spots shall be later patched or corrected in a manner acceptable to the Engineer. If the drop in water surface in the 24-hour period exceeds 1/10 of 1 percent of the normal volume of liquid contained in the water-holding structure, after accounting for evaporation and precipitation in open basins, the leakage shall be considered excessive. Evaporation shall be determined by floating an evaporation pan in the structure during the test period.
4. If the leakage is excessive, the basin shall be drained, all leaks previously marked shall be patched, and the necessary repairs made. The Contractor's method of repair shall be subject to the requirements of these Specifications and submitted for review by the Engineer.
5. The basin shall then be refilled and again tested for leakage. This process shall be continued until the drop in water surface in a 24-hour period with the basin full is less than 1/10 of 1 percent of the volume of liquid held in the basin. All
1.
repairs of faulty workmanship and materials, as well as additional testing, shall be made by the Contractor in an acceptable manner at no additional cost to the Owner. Both the correction for excessive leakage and the removal of the damp or wet spots on walls shall be required to pass the leakage test.
PART 2 PRODUCTS
Not Used.
PART 3 EXECUTION
3.1 TEST PROCEDURE
A. Fill tank to intended operating level:
1. Compute volume of tank to this level.
B. Measure water elevation on each tank wall at four equidistant points and average readings:
1. Provide stilling wells at each measuring point to dampen wave action.
2. Make measurements to 0.005 feet.
C. At end of test period measure water elevation to determine loss or gain volumetrically:
1. Correct for evaporation and rainfall.
D. Tanks initially passing leakage test shall have all visible leaks repaired prior to coating.
E. Perform following to tanks not meeting allowable leakage:
1. Locate leaks.
2. Drain tank and repair leaks.
3. Submit methodology and proposed materials for repairing of leaks to Engineer for review. Engineer will determine acceptability of proposed methods and materials.
4. Repair cracks.
5. Refill and retest tank.
6. Repeat repairing and testing procedures as many times as necessary to meet allowable leakage.
F. Water leakage testing shall be performed on the following structures:
1. RAS Denitrification Tank (Structure #32)
END OF SECTION
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