La. Admin. Code tit. 51 § XII-225

Current through Register Vol. 50, No. 11, November 20, 2024

Section XII-225 - General

A. The materials and designs used for finished water storage structures shall provide stability and durability as well as protect the quality of the stored water.

B. Steel structures shall be constructed in accordance with the American Water Works Association (AWWA) standards, incorporated by reference into these rules (see §277 for referenced standards) concerning steel tanks, standpipes, reservoirs, and elevated tanks wherever they are applicable. Other materials of construction are acceptable when properly designed to meet the requirements of this Subchapter.

C. Sizing. The following criteria applies to the sizing of storage facilities.

1. Storage facilities should have sufficient capacity, as determined from engineering studies, to meet domestic demands, and where fire protection is provided, fire flow demands.

2. The minimum storage capacity (or equivalent capacity) for systems not providing fire protection shall be equal to the average daily consumption.

a. This requirement may be reduced when the source and treatment facilities have sufficient capacity with standby power to supplement peak demands of the system.

3. Excessive storage capacity should be avoided to prevent potential water quality deterioration problems.

D. Location of Reservoirs. The following criteria applies to the location of reservoirs.

1. Ground level reservoirs shall be protected from contamination to a point two feet above the 100-year flood elevation requirements and from groundwater infiltration. Sewers, drains, standing water, and similar sources of possible contamination must be kept at least 50 feet from the reservoir. Gravity sewers constructed of water main quality pipe, pressure tested in place without leakage, may be used at distances greater than 20 feet but less than 50 feet.

2. The bottom of ground level reservoirs and standpipes should be placed at the normal ground surface. If the bottom of a storage reservoir shall be below the normal ground surface, at least 50 percent of the water depth must be above grade.

3. The top of a partially buried storage structure shall not be less than two feet above normal ground surface. Clearwells constructed under filters may be exempted from this requirement when the design provides adequate protection from contamination.

E. Protection from Contamination. All finished water storage structures shall have suitable watertight roofs which exclude birds, animals, insects, and excessive dust. The installation of appurtenances, such as antenna, shall be done in a manner that ensures no damage to the tank, coatings or water quality, or corrects any damage that occurred.

F. Protection from Trespassers. Fencing, locks on access manholes, and other necessary precautions shall be provided to prevent trespassing, vandalism, and sabotage. Consideration should be given to the installation of high strength, cut resistant locks or lock covers to prevent direct cutting of a lock.

G. Drains. No drain on a water storage structure may have a direct connection to a sewer or storm drain. The design shall allow draining the storage facility for cleaning or maintenance without causing loss of pressure in the distribution system.

H. Stored Water Age. Finished water storage designed to facilitate fire flow requirements and meet average daily consumption shall be designed to minimize stagnation and/or stored water age.

1. Consideration shall be given to separate inlet and outlet pipes, mechanical or similar mixing, or other acceptable means to prevent poor water circulation and long detention times that can lead to loss of disinfectant residual, microbial growth, formation of disinfectant byproducts, taste and odor problems, and other water quality problems.

I. Overflow. Water storage structure overflow shall comply with the following.

1. All water storage structures shall be provided with an overflow which is brought down to an elevation between 12 and 24 inches above the ground surface, and discharges over a drainage inlet structure or a splash plate. No overflow may be connected directly to a sewer or a storm drain. All overflow pipes shall be located so that any discharge is visible.

2. Certain pre-stressed concrete tanks having an overflow opening installed on the top or side of the tank shall not be required to have an internal overflow pipe as long as each opening is covered with an "eyelid" that prevents contamination of the water in the tank. The discharge from such overflow openings shall still be required to discharge over a splash plate large enough to prevent erosion of the tanks foundation or any other support structures. Caution shall be taken to ensure that any overflow down the outside of the tank will not affect electrical or cause other safety concerns.

a. When an internal overflow pipe is used on elevated tanks, it should be located in the access tube. For vertical drops on other types of storage facilities, the overflow pipe should be located on the outside of the structure.

b. The overflow for a ground-level storage reservoir shall open downward and be screened with twenty- four mesh non-corrodible screen. The screen shall be installed within the overflow pipe at a location least susceptible to damage by vandalism.

c. The overflow for an elevated tank shall open downward and be screened with a four mesh, non-corrodible screen to keep out animals or insects. The screen should be installed within the overflow pipe at a location least susceptible to damage by vandalism.

d. The overflow pipe shall be of sufficient diameter to permit waste of water in excess of the filling rate.

J. Access. Finished water storage structures shall be designed with reasonably convenient access to the interior for cleaning and maintenance. At least two (2) manholes shall be provided above the waterline at each water compartment where space permits.

1. Elevated Storage or Dome Roof Structures shall comply with the following.

a. At least one of the access manholes shall be framed at least four inches above the surface of the roof at the opening. They shall be fitted with a solid water tight cover which overlaps the framed opening and extends down around the frame at least two inches, shall be hinged on one side, and shall have a locking device.

b. All other manholes or access ways shall be bolted and gasketed according to the requirements of the state health officer, or shall meet the requirements of Subparagraph a of this Paragraph.

2. Ground Level or Flat Roof Structures shall comply with the following.

a. Each manhole shall be elevated at least 24 inches above the top of the tank or the finished grade of the surrounding ground, whichever is higher.

b. Each manhole shall be fitted with a solid water tight cover which overlaps a framed opening and extends down around the frame at least two inches. The frame shall be at least four inches high. Each cover shall be hinged on one side, and shall have a locking device.

K. Vents. Finished water storage structures shall be vented. The overflow pipe shall not be considered a vent. Open construction between the sidewall and roof is not permissible. The vents:

1. shall prevent the entrance of surface water and rainwater;

2. shall exclude birds and animals;

3. should exclude insects and dust, as much as this function can be made compatible with effective venting;

4. shall, on ground-level structures, open downward with the opening at least 24 inches above the roof and be covered with twenty-four mesh non-corrodible screen. The screen shall be installed within the pipe at a location least susceptible to vandalism;

5. shall, on ground storage tanks, open downward with the opening at least 24 inches above the finished grade of the surrounding ground and be covered with twenty-four mesh non-corrodible screen. The screen shall be installed within the pipe at a location least susceptible to vandalism; and

6. shall, on elevated tanks and standpipes, open downward, and be fitted with either four mesh non-corrodible screen, or with finer mesh non-corrodible screen in combination with an automatically resetting pressure-vacuum relief mechanism, as required by the state health officer.

L. Roof and Sidewalls. The roof and sidewalls of all water storage structures shall be watertight with no openings except properly constructed vents, manholes, overflows, risers, drains, pump mountings, control ports, or piping for inflow and outflow. Particular attention shall be given to the sealing of roof structures which are not integral to the tank body.

1. Any pipes running through the roof or sidewall of a metal storage structure must be welded, or properly gasketed. In concrete tanks, these pipes shall be connected to standard wall castings which were poured in place during the forming of the concrete. These wall castings should have seepage rings imbedded in the concrete.

2. Openings in the roof of a storage structure designed to accommodate control apparatus or pump columns, shall be curbed and sleeved with proper additional shielding to prevent contamination from surface or floor drainage.

3. Valves and controls should be located outside the storage structure so that the valve stems and similar projections will not pass through the roof or top of the reservoir.

4. The roof of the storage structure shall be well drained. Downspout pipes shall not enter or pass through the reservoir. Parapets, or similar construction which would tend to hold water and snow on the roof, will not be approved unless adequate waterproofing and drainage are provided.

5. The roof of concrete reservoirs with earthen cover shall be sloped to facilitate drainage. Consideration should be given to installation of an impermeable membrane roof covering.

6. Reservoirs with pre-cast concrete roof structures must be made watertight with the use of a waterproof membrane or similar product.

M. The material used in construction of reservoirs shall be acceptable to the state health officer. Porous material, including wood and concrete block, are not suitable for potable water contact applications.

N. Safety must be considered in the design of the storage structure. The design shall conform to applicable laws and regulations of the area where the water storage structure is constructed.

1. Ladders, ladder guards, balcony railings, and safely located entrance hatches shall be provided where applicable.

2. Elevated tanks with riser pipes over eight inches in diameter shall have protective bars over the riser openings inside the tank.

3. Confined space entry requirements shall be considered.

O. Freezing. Finished water storage structures and their appurtenances, especially the riser pipes, overflows, and vents, shall be designed to prevent freezing which will interfere with proper functioning.

1. Equipment used for freeze protection that will come into contact with the potable water shall meet NSF/ANSI Standard 61 or be approved by the state health officer.

2. If a water circulation system is used, it is recommended that the circulation pipe be located separately from the riser pipe.

P. Internal Catwalk. Every catwalk over finished water in a storage structure shall have a solid floor with sealed raised edges, designed to prevent contamination from shoe scrapings and dirt.

Q. Silt Stop. The discharge pipes from water storage structures shall be located in a manner that will prevent the flow of sediment into the distribution system. Removable silt stops should be provided.

R. Grading. The area surrounding a ground-level structure shall be graded in a manner that will prevent surface water from standing within 50 feet of it.

S. Painting and/or cathodic protection. Proper protection shall be given to metal surfaces by paints or other protective coatings, by cathodic protective devices, or by both.

1. Paint systems shall meet NSF/ANSI Standard 61 and be acceptable to the state health officer. Interior paint must be applied, cured, and used in a manner consistent with the NSF/ANSI approval. After curing, the coating shall not transfer any substance to the water which will be toxic or cause taste or odor problems. Prior to placing in service, an analysis for volatile organic compounds is advisable to establish that the coating is properly cured. Consideration should be given to 100 percent solids coatings.

2. Wax coatings for the tank interior shall not be used on new tanks or in the rehabilitation of existing tanks. Old wax coating must be completely removed before using another tank coating.

3. Cathodic protection should be designed and installed by competent technical personnel, and a maintenance contract should be provided.

T. Disinfection. Finished water storage structures shall be disinfected in accordance with AWWA Standard C652-11 (see Table 277).

1. If bacteriological testing for coliform organisms is negative and chlorine residuals are at acceptable distribution system levels, the storage tank may be placed into service. If such testing shows the presence of coliform bacteria, the tank cannot be placed into service and repeat samples shall be taken until two consecutive samples, taken at 24-hour intervals, are negative. The tank shall not be placed into service until the sample results are satisfactory.

2. Disposal of heavily chlorinated water from the tank disinfection process shall be in accordance with Paragraph 4.3.5.1 of AWWA Standard C652-11 or in accordance with the requirements of the Louisiana Department of Environmental Quality (LDEQ) or other state or federal authorities, whichever is stricter.

U. Smooth-nosed sampling tap(s) or similar non-threaded stainless steel sampling taps shall be provided to facilitate collection of water samples for both bacteriological and chemical analyses. The sample tap(s) shall be easily accessible.

La. Admin. Code tit. 51, § XII-225

Promulgated by the Department of Health, Office of Public Health, LR 44335 (2/1/2018), effective 8/1/2018.

AUTHORITY NOTE: Promulgated in accordance with the provisions of R.S. 40:4.A.(8), 40:4.13.D.(1)(2) and 40:5.A.(2)(3)(5)(6)(7)(17).