Section 810.14. Water storage facility inspections.

  The interior and exterior of water storage facilities serving public water systems shall be regularly inspected and maintained. Inspections of storage facilities 10,000 gallons or greater shall be by a professional tank inspection firm or by a registered professional engineer. Maintenance shall include removal of sediment and biofilm prior to evaluation of structural, mechanical and coating systems. Repairs shall be provided as necessary to ensure good working condition. Interior and exterior paint coatings for steel elevated water storage tanks or treatment structures shall be inspected by a person trained to evaluate the integrity of the paint system and repainted as necessary to maintain structural integrity. The water supplier may perform the inspection if experienced in paint inspection.

(1)   Frequency. All storage facilities shall be inspected a minimum of every 5 years and as required in sub. (2) (a) unless otherwise approved by the department. Repairs or welding on the exterior of a tank may make a special interior inspection necessary. Exterior inspections of vent and overflow screens and hatches shall be conducted once per year by the water supplier.

(2)   Methods. Any of the following methods are acceptable for the required 5-year interior tank/ water storage facility inspection:

(a) Drain down inspections. Drain down inspections include completely draining the tank. Rigging and ladders may be necessary to access all surfaces. The tank shall be cleaned of all sediment prior to inspecting. Unless an alternative schedule is approved by the department, a drain down inspection shall be utilized a minimum of every ten years or every other inspection.

1. Following all drain down inspections and painting, the interior of the tank shall be disinfected in accordance with one of the methods in AWWA Standard C652-02. A minimum of 2 successive safe samples, taken at 24-hour intervals, shall be obtained which indicate bacteriologically safe water; or one safe sample shall be obtained only if a free chlorine residual of at least 0.1 mg/l is remaining when the results of the safe sample are reported.

2. For all concrete ground reservoirs with cracks or signs of leakage, the top shall be soaked with water and the interior shall be checked for leaks.

(b) Float down or partial drain inspections. Float down inspections involve the use of a disinfected inflatable raft and allow access to all levels of the tank. The water level shall be lowered below the normal low operating level to expose the sidewalls of the tank. If the tank is to remain in service during the inspection or the water will be sent to the distribution system following the inspection, all of the following requirements apply:

1. A minimum 0.5 mg/l chlorine residual shall be maintained in the tank throughout the inspection.

2. All equipment shall be dedicated for potable water use and is disinfected with a 200 ppm chlorine solution.

3. For all concrete ground reservoirs with cracks or signs of leakage, the top shall be soaked with water and the interior shall be checked for leaks.

4. A minimum of 2 bacteriologically safe samples shall be obtained from the tank after the inspection, one following the inspection and one 24 hours later.

5. A minimum pressure of 35 psi shall be maintained throughout the distribution system during the inspection.

(c) Diver inspections. Diver inspections shall involve the use of a commercial diver tethered to, and in communication with, the outside. Procedures shall be done in accordance with Section 4.4 of AWWA Standard C652-02 and Section 12.0 of the Consensus Standards for Commercial Diving and Underwater Inspection. The department recommends that the tank be removed from service during the inspection. If the tank is to remain in service during the inspection or if the water will be sent to the distribution system following the inspection, all of the following requirements apply:

1. A minimum 0.5 mg/l chlorine residual shall be maintained in the tank throughout the inspection.

2. All equipment shall be dedicated for potable water use and shall be disinfected with a 200 ppm chlorine solution. The inspector shall also be disinfected.

3. The inspection of the tank shall be done after the sediment is removed from the bottom of tank and shall include a visual inspection of any expansion joints.

4. For all concrete ground reservoirs with cracks or signs of leakage, the top shall be soaked with water and the interior shall be checked for leaks.

5. A minimum of 2 bacteriologically safe samples shall be obtained from the tank after the inspection, one following the inspection and one 24 hours later.

(d) Robotic inspections. Robotic inspections shall involve a rover unit with a fiber optic tether and video camera and shall include cleaning capabilities. If the tank is to remain in service during the inspection or if the water will be sent to the distribution system following the inspection, all of the following requirements apply:

1. A minimum 0.5 mg/l chlorine residual shall be maintained in the tank throughout the inspection.

2. All equipment entering the tank shall be dedicated for potable water use and be disinfected with a 200 ppm chlorine solution.

3. For all concrete ground reservoirs with cracks or signs of leakage, the top shall be soaked with water and the interior shall be checked for leaks.

4. A minimum of 2 bacteriologically safe samples shall be obtained from the tank after the inspection, one immediately following the inspection and one 24 hours later.

(3)   Department notification. The department's regional drinking water staff person shall be given 48 hours prior notice of the date and time of the inspection.

(4)   Inspection report submittal. Upon completion of the water storage facility inspection, a completed department report form shall be submitted to the department's regional drinking water staff person documenting the condition of the storage facility. The water supplier shall submit copies of any additional reports and videos prepared by the inspector.

(5)   Manhole cover gasket. Following all inspections and maintenance, the integrity of the gasket between the access manhole cover and curbing shall be checked and replaced if necessary to prevent the entrance of dust and insects. If no gasket is present, one meeting s. NR 811.64 (7) requirements shall be provided to prevent the entrance of dust and insects.

History: CR 09-073 : cr. Register November 2010 No. 659 , eff. 12-1-10.

Note

The report forms are available from the department's regional or central office drinking water program staff. Microsoft Windows NT 6.1.7601 Service Pack 1