A_04__SOW_Rhyolite_Water_Tank_Cleaning.docx

Page | Statement Of Work Cleaning, Disinfecting, Testing, and Filling up 5,000-Gallon Potable Water Tank System Rhyolite Recreation Site, Near Beatty, Nevada

Background: Bureau of Land Management (BLM) has and maintains a Recreation Site at Rhyolite near town of Beatty. This site has a caretaker that camps at the site and maintains, watches, and guards the facilities to make sure visitors do not damage any of the buildings and amenities. Many years ago, BLM installed an underground water tank, a pump, and a piping system to provide potable water for use of the caretaker. City Water, from Indian Springs area, is brought and poured in the tank as frequently as needed. Water by means of a pump and gravity is flown through the pipe to a spigot next to the caretaker’s trailer. Approximate locations of the tank, pump, and spigot are shown in below photos. There is no record showing when the underground tank was cleaned and washed last. The tank is in need of cleaning.

Scope of Work:

Emptying and Cleaning Tank:

Empty the tank from any water by means of vacuuming or pumping. Make sure the pump is not running dry and avoid any damage to the pump. Remove any sludge, debris, corrosion, bio-film, sediments, and foreign objects inside the tank and clean the tank by any necessary means such as brushing and use of power washer equipment. Use a potable pump to flush out dirty water from the tank. Follow all Federal, State (such as Occupational Safety and Health Administration, OSHA), and local governing regulations (Confined Space). Fill the tank with potable water after cleaning is complete and verified by the COR to his/her satisfaction.

Disinfecting:

Disinfect the water distribution system as follows:

· Disinfectant: Shall be chlorine in the form of a hypochlorite solution.

· Dosage: Chlorine concentration in solution shall be 50 to 80 ppm,

· Filling System: Fill the entire water system with the chlorine solution according to AWWA C651 and C652 (AWWA.org). Open taps and valves and leave open until an odor of the disinfectant is noticeable in the water coming from the outlets. After this occurs, close the taps and valves. The tank full of water shall have free chlorine residual of 10 ppm.

· Testing Period: Allow disinfectant to remain in the system for approximately 24 hours. During the retention period, operate valves, stops, taps, and other appurtenances to assist the disinfection.

Flushing:

After the chlorine solution has sat in the tank for 24 hours, flush out/empty the storage tank. Do not drain the tank into a septic system or adjacent surface water body. Chlorine solution can kill the good bacteria in the septic system. Refill the tank and flush all taps until chlorine can no longer be smelled. If a portable pump is used, ensure that the intake hose is clean and wiped down with bleach to prevent contamination. Continue flushing until the waste water is clear and no chlorine odor is detected.

Testing:

Once the storage tank has been thoroughly flushed, test for free chlorine residual to ensure it is non-detectable (or zero). This can be done using an approved HACH DPD color metric test kit. Once a non-detectable chlorine residual has been obtained, collect operational & maintenance (O&M) total coliform bacteria water samples. If the test results are negative for bacteria, the drinking water is considered safe to use and drink.

Disinfection Materials:

The disinfection materials shall be:

· Calcium Hypochlorite: Shall be a commercial product having approximately 70 percent available chlorine by weight. Product shall comply with requirements of AWWA B 300.NN. Product shall be labeled and listed as NSF approved for use with potable water. A five-percent solution shall be made by mixing 5 percent of calcium hypochlorite with 95 percent water by weight. Make into a paste, then thin to slurry by the addition of water. CAUTION: When calcium hypochlorite is used as the source of chlorine, it should be dissolved or suspended in water when introduced into solvent-welded PVC pipe (The dry chemical can react violently with solvent-welding materials). Precautions listed on the calcium-hypochlorite container shall be followed. Safety precautions and personal protective equipment shall be used, as required.

· Sodium Hypochlorite: AWWA B 300.

Dispose the residual chlorinated water in a legal manner.

Disinfection Report:

The report shall include the following:

· Type and form of disinfectant used.

· Date and time of disinfectant injection start time and completion time.

· Test locations.

· Initial and 24-hour disinfectant residuals (quantity in treated water) in parts per million (ppm) for each outlet sampled /tested.

· Date and time of flushing start and completion.

· Disinfectant residual after flushing in ppm for each outlet tested.

Bacteriological Examination and Report:

Take samples according to AWWA C651 and C652, Sections 9 and 10 (Sample must be in test laboratory less than 30 hours after sampling for laboratory testing) and obtain certified test results. Provide the results to the COR.

The report shall include the following:

· Date issued, project name, and testing laboratory name, address, and telephone number.

· Time and date of water sample collection.

· Name of person collecting samples.

· Sample locations described for testing and lab reporting.

· Coliform bacteria test results for each outlet tested.

· Certification that water conforms, or fails to conform, to bacterial standards of State of Nevada and Nye County.

· Bacteriologist's signature.

Testing Laboratory:

The laboratory shall be certified as an approved laboratory for examination of drinking water in compliance with applicable regulations of the State of Nevada, Division of Health (Safe Drinking Water Act).

US 95

to from Las Vegas to Tonopah Rhyolite Beaty

US 95

from Beatty to Las Vegas

HWY. 374

Caretaker Camp Site

Approximate Location of Sp igot Approximate Location of Water Tank

WATER TANK LOCTAION

WATER TANK & WATER PUMP LOCATION

Water Pump Location Caretaker Camp Site

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