W. Va. Code R. § 64-47-4

Current through Register Vol. XLI, No. 45, November 8, 2024

Section 64-47-4 - Sewage Collection Systems

4.1. General.

4.1.a. Design. The design of new systems or extensions to existing systems shall carry sanitary sewage flows plus contain an allowance for non-excessive infiltration.

4.1.b. Modifications. Modifications to the design on existing systems shall be to carry sanitary sewage flows plus contain an allowance for non-excessive infiltration and inflow.

4.1.c. Overflows. The Commissioner shall review on a case-by-case basis, overflows from new interceptor sewers.

4.1.d. Combined Sewers. The Commissioner shall not approve new combined systems.

4.1.e. Design Factors. In determining the required capacities of sanitary sewers, an applicant shall consider the following factors:

4.1.e.1. Maximum hourly quantity of sewage;

4.1.e.2. Additional maximum wastewater flow from industrial plants; and

4.1.e.3. Groundwater infiltration.

4.1.f. Design Basis Per Capita Flow. To arrive at average dry weather flows from combined residential, commercial, and institutional sources, an applicant shall design a new system on the basis of one of the following two methods:

4.1.f.1. Using estimates based on a one-year record of a fully documented analysis of water use adjusted for consumption and losses; or

4.1.f.2. Using state developed per capita wastewater flows using 70 GPCD or existing water usage records for various sizes and types of municipalities.

4.2. Gravity.

4.2.a. Design Period. The maximum allowable design period for sewers is 50 years for the estimated tributary area. This rule shall allow phasing of collection system.

4.2.b. Infiltration Allowance and Industrial Flows. The Commissioner may add an infiltration allowance to the per capita design flows of 200 gallons per inch diameter per mile per day and a reasonable allowance for future industries to arrive at the average daily flow (ADF).

4.2.c. Peak Flows.

4.2.c.1. When flowing full, an applicant shall make sewer designs to carry a peak flow of:

4.2.c.1.A. Lateral Sewers - 4 x ADF; and

4.2.c.1.B. Trunk and Interceptor and Outfall Sewers - 2.5 x ADF.

4.2.d. When deviating from the above stated peak design flows, an applicant shall provide in the design engineering report a brief justification and description of the procedure he or she used for sewer design.

4.2.e. Calculation. An applicant shall present computations and other design data for proposed sewage collection and treatment facilities of greater than 100,000 gallons per day, in an appropriate form to the Commissioner. The computations shall include:

4.2.e.1. Average daily flow and peak daily flow at critical points such as the change in size of sewers; and

4.2.e.2. The velocity at minimum, average and peak flows in sewers, as required.

4.2.f. Minimum Size.

4.2.f.1. No gravity sewer shall be less than eight inches in diameter except for using six inch diameter sewer pipe for lateral sewers when:

4.2.f.1.A. No possibility of future extension exists; and

4.2.f.2.B. The sewer cannot service more than either 30 mobile homes or 23 residences.

4.2.f.2. There shall be no allowance for a four-inch sewer pipe for the gravity collection system.

4.2.g. Small Diameter-Gravity Sewers.

4.2.g.1. On a case-by-case basis the Commissioner may allow these sewers for sanitary sewage collection.

4.2.g.2. Pretreatment is a requirement prior to discharge into these small diameter-gravity sewers.

4.2.g.3. The minimum pipe size is four inches.

4.2.g.4. An applicant may use cleanouts instead of manholes and shall install them:

4.2.g.4.A. At all changes in direction; and

4.2.g.4.B. At all connections.

4.2.h. Cover. The minimum allowable earth cover on sewers is three feet unless otherwise approved by the Commissioner. Generally, sewers shall be sufficiently deep enough to drain basement fixtures, to protect the sewers from surface loadings and to prevent freezing.

4.2.i. Slope.

4.2.i.1. For new sewers, the design and construction shall be to give velocities, when flowing full, of not less than two feet per second based on Kutter's or Manning's formula using an "n" value of 0.013.

4.2.i.2. For existing sewers, the Commissioner recommends a value of "n" as 0.015 to determine existing capacities. The Commissioner shall grant permission to use other practical "n" values if he or she considers it justifiable on the basis of research or field data an applicant presents.

4.2.i.3. The Commissioner recommends slopes greater than the ones in Table 64-47-C. at the end of this rule that contains minimum required slopes.

4.2.i.4. Under special conditions, if detailed data given are justifiable, the Commissioner may grant an applicant permission to use slopes slightly less than those required for the two feet per second velocity when flowing full. When selecting decreased slopes, the engineer shall provide the Commissioner a report and the computations of the depth of flow in the pipes at minimum, average, and peak rates of flow. This rule recognizes that the decreased slopes may cause additional sewer maintenance.

4.2.i.5. Sewers shall lay in a straight line with uniform slope between manholes. Concrete anchors, or approved equal, shall anchor sewers laid on a 20% slope or greater and spaced as follows:

4.2.i.5.A. Not over 36 feet center to center on slopes between 20% to 35%.

4.2.i.5.B. Not over 24 feet center to center on slopes between 35% to 50%.

4.2.i.5.C. Not over 16 feet center to center on slopes 50% and over.

4.2.j. Alignment. Sewers 24 inches in diameter or less shall lay with straight alignment between manholes.

4.2.k. Increasing Size. When a sewer joins a larger one, the invert of the larger sewer shall be sufficiently lower to maintain the same energy gradient. An approximate method for securing these results is to place the 0.8 depth of both sewers at the same elevation.

4.2.l. High Velocity Protection. An applicant shall make special provisions to protect against displacement by erosion and shock when velocities are greater than 15 feet per second.

4.2.m. Materials. The material selected for the pipe shall be adaptable to local conditions, such as character of industrial wastes, possibility of septicity, soil characteristics, exceptionally heavy external loadings, abrasion, and similar problems.

4.2.n. Types of Gravity Pipe. Design of all sewers shall be to prevent damage from superimposed loads. Proper allowance for loads on the sewer shall be according to the width and depth of trench. Construction of gravity sewer lines shall be of clay, plastic, ductile iron, or concrete sewer pipe meeting the following minimum specifications:

4.2.n.1. House Connection to Collector Sewers:

Clay - ASTM C 700

Plastic - ASTM D 2729, D 2751, D 2836, D 2852

Ductile Iron - AWWA C-110, C-151, Cement lined

Concrete - ASTM C 14

4.2.n.2. Collector and Interceptor Sewers:

Clay - ASTM C 700 - Joints meet the requirements of ASTM C 425. This rule does not permit seal joints or cement joints.

Plastic-ASTM D 3033, D 3034, F 789, A 2000

Composite - ASTM D 2680

Ductile Iron - AWWA C-110, C-151, Cement lined

Concrete - ASTM C-76

4.2.o. Bedding. In accordance with ASCE Manual & Report on Engineering Practice No. 37, bedding shall be Class "A", "B", "C." To provide the strength necessary for future soil and load conditions, the engineer shall determine the class of bedding.

4.2.p. Inverted Siphons. Inverted siphons shall have not less than two barrels, with a minimum pipe size of six inches, and be provided with necessary appurtenances for convenient flushing and maintenance. The manholes shall have adequate clearances for rodding; and in general, provide sufficient head and pipe sizes selected to secure velocities of at least three feet per second for average flows. Arrangement of the inlet and outlet details shall be to divert the normal flow to one barrel in order to take either barrel out of service for cleaning. Use of ductile iron pipe or equal is a requirement.

4.2.q. Stream Crossing. When sewers must cross under a stream or watercourse, there shall be a minimum separation of three feet between the stream bed and the top of the sewer pipe. However, the Commissioner may approve other methods provided there is equivalent protection and performance. Use of ductile iron pipe or equal is a requirement.

4.2.r. Aerial Sewers. Aerial sewers require the Commissioner's prior approval.

4.2.s. Protection of Drinking Water Supplies.

4.2.s.1. Water Supply Interconnections. There shall be no physical connection between a public or private drinking water supply system and a sewer or appurtenance.

4.2.s.2. Relation to Public Water Systems. A general guideline is that gravity or pressure sanitary sewers, or both, shall be at least 10 feet horizontally from a drinking water supply.

4.2.s.3. Relation to Wells. No gravity or pressure sanitary sewer line shall be located within 50 feet of a public, private, or individual homeowner's drinking water well. However, if physical limitations prevent a 50-foot separation, the Commissioner may give written approval for variance from these requirements. Under no conditions shall the construction of any gravity or pressure sanitary sewer be closer than 10 feet to a private homeowner's well.

4.2.s.4. Relation to Water Lines.

4.2.s.4.A. Horizontal Separation. Gravity or pressure sanitary sewers shall be at a minimum of 10 feet horizontally away from any existing or proposed water lines. However, if maintaining the 10-foot horizontal separation is not possible, the construction of the sewer and testing shall be as prescribed in paragraph 4.2.s.5. of this rule. A sewer shall not be constructed closer than three feet edge to edge to a water line.

4.2.s.4.B. Vertical Separation. When a gravity or pressure sanitary sewer must cross water lines, its construction shall be at an elevation so that the top of the sewer line is a minimum of 18 inches beneath the bottom of the water main. However, if meeting the 18-inch vertical separation requirement is not possible, then the construction of the sewer and testing shall be as prescribed in paragraph 4.2.s.5. of this rule.

4.2.s.5. Special Construction Requirements.

4.2.s.5.A. Horizontal. In cases where water and gravity or pressure sanitary sewer lines must lay closer than 10 feet apart, the sewer line construction shall be a minimum of 18 inches lower than the water line and constructed of a pressure type pipe meeting requirements for water lines. The installation shall undergo hydraulic testing for a period of not less than 24 hours and considered satisfactory if leakage is not more than 0.25 gallons per inch diameter of pipe per joint. In lieu of hydraulic testing, the sewer line can be air tested. The placement of the water line shall be upon an undisturbed earth shelf or bench. Backfilling to create the bench is not permissible. Maintaining maximum possible horizontal distance between the lines is a requirement. Where meeting these conditions is not possible, an applicant shall obtain written approval for a variance from the Commissioner. When placement of the lines is within five feet of each other, each line shall have a metallic impregnated, permanent identification tape buried directly above it denoting "sewer line" or "potable water line."

4.2.s.5.B. Vertical. If maintaining a vertical clearance of 18 inches as specified in subparagraph 4.2.s.4.B. of this rule is not possible, the location of the gravity or pressure sanitary sewer shall be so that it crosses between joints of the water line. Also, construction of the sewer line shall be so that it crosses under the water line at mid joint. The construction of the sewer shall be of a pressure type pipe meeting the requirements for water lines at the crossing. This rule requires maintaining a minimum vertical clearance of six inches between the sewer and water lines. The construction of a gravity or pressure sanitary sewer line, or both, shall not be over the top of a water line. However, when meeting the standard vertical installation requirements is not possible, encase the sewer line so that the casing extends at least 10 feet on each side of the crossing. This rule requires maintaining a minimum vertical separation of 18 inches between the lines.

4.2.t. Sewer Riser Pipes.

4.2.t.1. All mobile home lots shall have a sewer riser pipe with a minimum diameter of four inches and extend at least four inches above the ground in a vertical position.

4.2.t.2. When not serving a mobile home, all sewer riser pipes shall be tightly capped or plugged to keep them watertight.

4.3. Manholes.

4.3.a. Location. Manholes shall be placed:

4.3.a.1. At the end of each sewer line;

4.3.a.2. At all changes in slope, size, or alignment;

4.3.a.3. At all intersections; and

4.3.a.4. At distances not greater than 400 feet for sewers 15 inches in diameter or less, and 500 feet for sewers 18 inches to 30 inches in diameter. The Commissioner may waive this requirement and permit greater spacing in larger sewers and in sewers carrying settled effluent.

4.3.a.5. This rule allows for the construction of cleanouts at the upper end of all lines. In some special conditions, cleanouts may replace manholes, but installation of them requires approval by the Commissioner prior to installation.

4.3.b. Materials. Manholes shall be pre-cast concrete, poured-in-place concrete, or concrete manhole block.

4.3.c. Drop Type. A sewer entering a manhole at an elevation of 24 inches or more above the manhole invert provides for outside drop pipe. The entire drop connection shall be encased in concrete. If an inside drop is necessary, the manhole and access provided for cleaning shall have a pipe fastened to it.

4.3.d. Diameter. The minimum base diameter of manholes shall be 48 inches. Larger diameters are preferable for large diameter sewers with a minimum opening of 24 inches.

4.3.e. Steps. There shall be a provision for non-corrosive steps embedded in the walls, offset and spaced 12 to 18 inches apart vertically.

4.3.f. Flow Channel. The inside base of the manhole shall be filled with concrete to form a bench sloping toward the flow channel. In addition, both the flow channel and the bench shall be troweled to a smooth surface.

4.3.g. Watertightness. Solid manhole covers are required where the manhole covers may flood by street runoff or high water.

4.3.g.1. Manholes of segmented block shall have waterproofing on the exterior with plaster coatings, supplemented by a bituminous waterproof coating;

4.3.g.2. Concrete manholes shall have waterproofing on the exterior where groundwater conditions are unfavorable; and

4.3.g.3. Pipe connections to manholes and joints on manholes shall be watertight.

4.4. Pumping Station.

4.4.a. General.

4.4.a.1. Flooding. The location of stations including electrical equipment shall be at an elevation not subject to the 100-year flood or otherwise have adequate protection against the 100-year flood.

4.4.a.2. Location.

4.4.a.2.A. Preferably, the location shall be off the right-of-way of streets and alleys and shall be a suitable structure;

4.4.a.2.B. The station shall be readily accessible, but be as far as possible from the nearest dwelling; and

4.4.a.2.C. Fencing shall be required to prevent entry of unauthorized persons unless the Commissioner gives prior approval for an alternative method.

4.4.a.3. Overflows. There shall be no overflows or bypasses from lift stations at new facilities.

4.4.a.4. Pumping Rates and Number of Pumping Units. All lift stations, each capable of providing the maximum design flow, shall have minimum dual pumps. The size of the pumping units shall be to provide the minimum cleaning velocity of two feet per second at the rated capacity, assuming a C=120 for plastic pipe and C=100 for all other pipe materials in the Hazed-Williams Formula.

4.4.a.5. Type. The Commissioner may approve the wet well or wet well/dry well type, or both.

4.4.b. Design.

4.4.b.1. Long Drive Shaft Pumps. A wet well installation achieved by mounting the pump in the wet well and connecting it by a drive shaft to the motor above the wet well shall not be approved.

4.4.b.2. Separation. There shall be complete separation of the wet well and dry well, including its superstructure.

4.4.b.3. Pump Removal. There shall be provisions to facilitate removing pumps and motors.

4.4.b.4. Access. Dry wells of pumping stations and wet wells containing either bar screens or mechanical equipment requiring inspection or maintenance shall have suitable and safe means of access.

4.4.b.5. Size. The effective capacity of the wet well shall provide a detention time not exceeding 30 minutes for the design average flow.

4.4.b.6. Floor Slope. The wet well floor shall have a minimum slope of one to one towards the hopper bottom. The horizontal area of the hopper bottom shall be no greater than necessary for proper installation and function of the inlet. Bottoms shall have a smooth finish.

4.4.b.7. Protection Against Clogging.

4.4.b.7.A. Readily accessible bar screens with clear openings not exceeding 2.5 inches, unless using pneumatic ejectors or installing special devices to protect the pumps from clogging or damage, may precede pumps handling raw sewage;

4.4.b.7.B. Where the size of the installation warrants, this rule recommends a mechanically cleaned bar screen with a grinder or comminution device;

4.4.b.7.C. There shall be convenient facilities for handling screenings where screens are located; and

4.4.b.7.D. It is preferable to use duplicate protection units of proper capacity for the larger or deeper sections.

4.4.b.8. Pump Openings.

4.4.b.8.A. Pumps shall be capable of passing 2.5-inch solids or be of the grinder pump type when used in residential developments of 500 persons or less;

4.4.b.8.B. Pumps for all other installations shall be capable of passing three-inch solids or be of the grinder pump type; and

4.4.b.8.C. Pumps shall be non-clog type pumps or ejectors.

4.4.b.9. Priming. The placing of the pump shall be so that under normal operating conditions it shall operate under a positive suction head, except as specified for suction lift pumps.

4.4.b.10. Electrical Equipment. Electrical systems and components such as motors, lights, cables, conduits, switch boxes, and control circuits, in enclosed or partially enclosed spaces, shall be of materials resistant to the environment when usage takes place.

4.4.b.11. Intake. Each pump shall have an individual intake. Wet well design shall be such as to avoid turbulence near the intake.

4.4.b.12. Dry Well Dewatering.

4.4.b.12.A. The dry wells shall have a separate pump in them to remove leakage or drainage with the discharge above the overflow level of the wet well;

4.4.b.12.B. A connection to pump suction may be used as an auxiliary feature;

4.4.b.12.C. Water ejectors connected to a drinking water supply shall not be approved; and

4.4.b.12.D. All floor and walkway surfaces shall have an adequate slope to a point of drainage.

4.4.b.13. Controls.

4.4.b.13.A. Control float cables' location shall not be affected by the flows entering the wet well or by the suction of pumps;

4.4.b.13.B. Float tubes in dry wells shall extend high enough to prevent overflow;

4.4.b.13.C. A means to automatically alternate the pump in use shall be in place; and

4.4.b.13.D. Pump stations with motors or controls below grade shall have a secure external disconnect switch.

4.4.b.14. Valves and Piping.

4.4.b.14.A. Pumps shall have a full closing valve on the suction piping except on submersible and vacuum primed pumps;

4.4.b.14.B. The installation of a check valve followed by a gate valve on the discharge piping is required; and

4.4.b.14.C. The location of the valves shall not be in a wet well.

4.4.b.15. Ventilation. All dry well installations shall have mechanical ventilation.

4.4.b.15.A. Wet Wells. Ventilation shall be either continuous or intermittent.

4.4.b.15.A.1. If continuous, ventilation shall provide at least 12 complete air changes per hour; and

4.4.b.15.A.2. If intermittent, ventilation shall provide at least 30 complete air changes per hour.

4.4.b.15.B. Dry Wells. Ventilation shall be either continuous or intermittent.

4.4.b.15.B.1. If continuous, ventilation shall provide at least six complete air changes per hour; and

4.4.b.15.B.2. If intermit-tent, ventilation shall provide at least 30 complete air changes per hour.

4.4.b.16. Flow Measurement. There shall be the capability for placing suitable devices for measuring sewage flow at all pumping stations, and the devices shall be placed at critically located pumping stations.

4.4.b.17. Water Supply. There shall be no physical connection between any potable water supply and a sewage pumping station.

4.4.b.18. Alarm Systems. All pump station installations shall equip a high-water alarm light at the lift station.

4.4.b.19. Reliability. At the determination of the Commissioner, emergency power may be a requirement under specific circumstances, such as above water intakes, recreational waters, or other situations.

4.4.b.20. Portable Equipment. In some instances, portable equipment may furnish service to more than one pumping station. However, when using this equipment, it shall have the capability to operate between the wet well and the discharge side of the station. The station shall equip permanent fixtures that shall facilitate rapid and easy connection of lines.

4.4.b.21. Emergency Power Generation. All emergency power generation equipment, if required, shall include instructions indicating the essential need of routinely and regularly starting and running the units at full load.

4.4.c. Suction Lift Pumps.

4.4.c.1. Suction lift pumps shall be of the self-priming or vacuum priming type.

4.4.c.1.A. Self-priming Pumps. Self-priming pumps shall be capable of rapid priming and repriming at the "lead pump on" elevation. Accomplishing the self-priming and repriming shall be automatic under design operating conditions. Suction piping shall not exceed the size of the pump suction and shall not exceed 25 feet in total length. Priming lift at the "lead pump on" elevation shall include a safety factor of at least four feet from the maximum allowable priming lift for the specific equipment at design operating conditions. The combined total of dynamic suction lift at the "pump off" elevation and required net positive suction head at design operating conditions shall not exceed 22 feet.

4.4.c.1.B. Vacuum-priming Pump Stations. Vacuum-priming pump stations shall equip dual vacuum pumps capable of automatically and completely removing air from the suction lift pump. The vacuum pumps shall have adequate protection from damage due to sewage. The combined total of dynamic suction lift at the "pump off" elevation and required net positive suction head at design operating conditions shall not exceed 22 feet.

4.4.c.2. The net positive suction head and specific speed requirements as stated on the manufacturer's pump curve under the most severe operating conditions shall limit the capacity of a suction lift pump.

4.4.c.3. The location of the suction lift pumps shall not be within the wet well.

4.4.c.4. Access to the wet well shall not be through the dry well, and the dry well shall have a gas-tight seal when mounted directly above the wet well.

4.4.d. Submersible Pumps.

4.4.d.1. Pump Removal. Pumps shall be readily removable and replaceable without dewatering the wet well or disconnecting any piping in the wet well.

4.4.d.2. Hoist Provision. The Commissioner may require a submersible pumping facility to have a hoist for removing the pump from the wet well.

4.4.d.3. Electrical Control Location. The location of electrical controls shall be outside the wet well in a suitable housing for protection against weather and vandalism.

4.4.e. Pneumatic Ejectors.

4.4.e.1. Venting. This rule requires the venting of ejector pots to the atmosphere.

4.4.e.2. Duplicate Compressors. There shall be duplicate compressors and consideration shall be given to providing an air storage tank.

4.4.f. Force Mains.

4.4.f.1. Size. Minimum size of force mains to serve facilities having a population of 500 people or less shall be three inches for solids passing pumps. Minimum size of force mains serving populations of over 500 people, shall be four inches for solids passing pumps. Applicant may utilize smaller size force mains in conjunction with grinder pumps.

4.4.f.2. Air Relief Valve. Placement of air relief valves shall be at high points in the force mains.

4.4.f.3. Termination. The force mains shall enter the receiving manhole with its center-line horizontal and with an invert elevation that shall insure a smooth laminar flow transition to the gravity flow section, but in no case shall the force main enter the gravity sewer system at a point more than one foot above the flow line of the receiving manhole.

4.4.f.4. Materials of Construction. The construction of force mains shall be of plastic, ductile iron or cement lined steel pipe bearing the pressure class required by the total dynamic head.

4.4.f.5. Anchoring. Anchoring of the force mains shall be sufficient within the pump station and throughout the line length. The number of bends shall be as few as possible. There shall be thrust blocks, restrained joints, or tie rods where there is a need for restraint.

4.5. Vacuum Sewage Collection Systems.

4.5.a. Main Lines.

4.5.a.1. Materials.

4.5.a.1.A. PVC or ABS of schedule 40 DWV, Class 200, or SDR 21.

4.5.a.1.B. Joints may be either solvent welded, O-ring, or heat fusion joints, that have a specific design to seal against vacuum.

4.5.a.2. Piping.

4.5.a.2.A. Minimum diameter pipe size shall be three inches in the collection system.

4.5.a.2.B. There shall be cleanouts at a maximum of every 200 feet on straight runs and at changes in direction.

4.5.a.2.C. Frost depth or load condition shall dictate how deep to bury the line, but except as allowed on a case-by-case basis by the Commissioner, it shall be no less than three feet deep.

4.5.a.2.D. The system manufacturer shall certify all vacuum system designs.

4.5.a.2.E. The applicant shall utilize the manufacturer's recommendation for reform pockets and lifts.

4.5.a.2.F. Total available head loss from any input point should not exceed 18 feet of water. There shall be a reserve of five feet of water for valve operation.

4.5.a.2.G. Installation of the collection system shall meet the following tightness test specification, "the system shall be vacuumed to 24 inches of mercury vacuum pressure, allowed 15 minutes to stabilize, and thereafter shall not lose more than 1% vacuum pressure per hour over a minimum of a four-hour period." There shall be testing prior to the installation of valves.

4.5.b. House Connections.

4.5.b.1. Pneumatic or electric controllers shall actuate valves. This rule prohibits valve systems that are electrically controlled. Minimum valve size shall be three inches.

4.5.b.2. The location of the valve shall be outside the dwelling. The location of the pipe between the dwelling and valve shall be to provide 10 to 15 gallons storage, or the location of a 30-gallon tank shall be between the dwelling and the valve. This rule requires a permanent maintenance easement for the valve and its appurtenances.

4.5.b.3. Valve boxes shall have a solid bottom and be counter weighted to prevent flotation when located in an area subject to flooding or high ground water. The cover and valve box material shall be of adequate strength to withstand the expected maximum dynamic and static loading conditions. Venting valve boxes shall reduce condensation and shall be constructed of corrosion resistant material.

4.5.b.4. The vent system for the house shall have a diameter of three inches or greater to prevent evacuation of traps during vacuum valve operation. The vent pipe shall extend above the eaves of the house. The commissioner shall consider other methods for venting on a case-by-case basis.

4.5.b.5. Those systems using a pneumatic controller shall have adequate protection of the sensor controllers, and any portion of the controller apparatus vented to atmosphere shall have protection from flooding, screened from insect entry, and provided with rain covers.

4.5.c. Sewage Collection Tanks.

4.5.c.1. The sewage collection tanks shall be of either coated welded steel or fiber glass and shall be vacuum tight.

4.5.c.2. Each inlet to the tank shall have its own shut-off valve.

4.5.c.3. There shall be liquid level sensors installed to operate the discharge sewage pumps, the high-level alarm and to interrupt the electrical power to the vacuum pumps.

4.5.c.4. The size of the collection tank shall be to hold a maximum of 10 minutes design flow. The size of the collection tanks shall be at 1.5 x operating volume or a minimum of 400 gallons.

4.5.d. Vacuum Pumps.

4.5.d.1. There shall be vacuum reserve tanks installed in series between the sewage collection tank and the vacuum pumps.

4.5.d.2. This rule allows for the use of either liquid ring or sliding vane vacuum pumps as long as they are compatible with pumping moist air containing some sewer gases.

4.5.d.3. There shall be a check valve installed between the vacuum reservoir tank and the vacuum pumps.

4.5.d.4. There shall be dual vacuum pumps, each capable of handling the load, and emergency back-up power.

4.5.d.5. Venting the vacuum pump exhaust outside the building is a requirement. If there is a possibility of objectional odors due to proximity of inhabited dwellings, the evacuation line from the vacuum reserve shall have carbon absorption.

4.5.e. Sewage Pumps.

4.5.e.1. There shall be dual pumps, each capable of handling 2.5 times the average daily flow.

4.5.e.2. There shall be emergency back-up power to operate the entire system.

4.5.e.3. The sewage pumps shall be capable of meeting the NPSH requirements as dictated by the vacuum conditions in the sewage collection tanks.

4.5.e.4. There shall be shut-off valves so that each pump can be isolated for repairs.

4.5.e.5. The discharge piping shall incorporate a check valve/gate valve arrangement such as utilized in a conventional pump station.

4.5.e.6. High level alarms and loss of vacuum alarms shall be capable of transmitting to three or more responsible parties.

4.5.f. Design Requirements.

4.5.f.1. It is a requirement to submit hydraulic calculations for the vacuum mains and force mains with the application.

4.5.f.2. It is a requirement to submit plans and profiles of all mains. Profiles shall indicate depth to mains, and plans shall indicate all valves.

4.5.f.3. When these standards are not applicable, it is a requirement to follow the manufacturer's recommendations.

4.5.g. Maintenance and Operation.

4.5.g.1. Factory trained maintenance personnel employed by the entity shall be available 24 hours per day.

4.5.g.2. An applicant shall keep an inventory of parts including spare valves, controllers, valve pits, and others.

4.5.g.3. This rule does not allow mixing of equipment such as different makes and models, for a specific project.

4.5.h. Miscellaneous.

4.5.h.1. Collection stations shall equip ventilators and heater dehumidifiers.

4.5.h.2. Branch lines shall have individual cut off valves to allow isolation of the line for repair. Main line sections shall have isolation valves no less than 2,000 feet apart.

4.5.h.3. Consideration to lessen the size of the treatment units in new systems that utilize water saving devices such as vacuum toilets, shall be based upon review and approval by the Commissioner.

4.5.h.4. Retaining spare controllers, valves, and sensors shall be on a basis of one per each 15 units installed.

4.5.h.5. House vent stacks shall be at least three inches in diameter. If necessary, there shall be an installation of a three- to four-inch stack on the gravity sewer lateral adjacent to the house wall.

4.5.i. Relation of vacuum lines to water lines shall be as for gravity lines. See paragraph 4.2.s.4. of this rule.

4.6. Pressure Sewage Collection System.

4.6.a. General.

4.6.a.1. Simplex units shall serve no more than three residences. Duplex units shall serve no more than 10 residences. Other multiple source applications require approval by the Commissioner. This rule requires spare pumps.

4.6.a.2. Types of Pressure Systems.

4.6.a.2.A. Grinder Pump Pressure System.

4.6.a.2.B. Septic Tank Effluent Pumping Pressure System.

4.6.a.3. Types of Pumps.

4.6.a.3.A. Submersible, Centrifugal Grinder Pumps. Pumps shall be readily removable and replaceable without dewatering the wet well.

4.6.a.3.B. Semi-Positive Displacement Grinder Pumps. Pumps shall be readily removable and replaceable without dewatering the wet well. There shall be pressure relief valves unless the Commissioner approves another means of pressure relief.

4.6.a.3.C. Non-Clog Submersible Centrifugal Effluent Pumps.

4.6.b. Design Requirements.

4.6.b.1. Hydraulic Calculations. Submitting calculations with the application is a requirement.

4.6.b.1.A. The determination of peak flows shall be from the manufacturers recommendations based upon the pumping equipment the system is using.

4.6.b.1.B. There shall be head losses due to valves and fittings.

4.6.b.1.C. For purposes of calculation, using a C=100 in the Hazen-Williams Formula for all pipe, except for using a C=120 for plastic pipe is a requirement.

4.6.b.1.D. Design velocity shall be in the range of two to five feet per second.

4.6.b.1.E. Computed design life of the pumps shall be on the basis of 10 years.

4.6.b.2. Plans. Submitting plans and profiles of all pressure mains is a requirement. Profiles shall indicate depth of pressure mains. The plans shall indicate all valves.

4.6.b.3. Design. The design shall be in accordance with the standards herewith stated, except when not covered by this standard, then following the manufacturer's recommendations is a requirement.

4.6.c. Pressure Mains.

4.6.c.1. Type. Minimum Pressure Rating - PVC SDR 21, Schedule 40, or PVC SDR 26 may be used.

4.6.c.2. Size. The minimum size service line from the grinder pump to the collection main shall be one and 1.25 inches.

4.6.c.3. Valves and Cleanouts.

4.6.c.3.A. Valving mains shall occur at junctions in order that segments of the system may be taken out of service for maintenance.

4.6.c.3.B. Cleanouts shall be at junctions so that lines may be cleaned.

4.6.c.3.C. The placement of cleanouts with valves shall be at every 400 to 600 feet on straight runs.

4.6.c.3.D. The location of cleanouts and valves shall be at changes in direction of the lines.

4.6.c.3.E. There shall be air release valves at high points in the line.

4.6.c.3.F. There shall be ball or gate valves with cleanouts at the ends of lines.

4.6.c.3.G. There shall be a method of providing continuity of service for main collector lines.

4.6.c.4. Thrust Blocks. There shall be concrete thrust blocks at changes in direction and at "T" junctions.

4.6.c.5. Flushing. This rule requires using one of the following methods:

4.6.c.5.A. Flush tanks of 1,000 gallons capacity with pumps at the ends of lines;

4.6.c.5.B. Water hydrants with backflow preventers at the end of lines, the backflow preventer shall be of the reduced pressure type and shall be non-removable; or

4.6.c.5.C. Water tank truck with pumps.

4.6.c.6. Relation to water lines shall be as for gravity lines. See paragraph 4.2.s.4. of this rule.

4.6.d. Grinder Pump Pressure System.

4.6.d.1. Location.

4.6.d.1.A. The location of the pump station shall be outside the residence or commercial building.

4.6.d.1.B. The location of the control box for a single residence unit shall be on the outside of the building, preferably with the pump station.

4.6.d.1.C. For duplex grinder pump stations, the location of the control box shall be with the pump station.

4.6.d.2. Electrical.

4.6.d.2.A. Control panels shall be of the NEMA type 3 or 4 enclosure.

4.6.d.2.B. The pump and float electrical controls shall have provisions for disconnection without entering the main control box.

4.6.d.3. Alarms.

4.6.d.3.A. When using a single unit grinder pump station, there shall be a high-water alarm light outside the residence.

4.6.d.3.B. When using a dual grinder pump station, there shall be an alarm light at the control box by the pump station.

4.6.d.4. Emergency Holding.

4.6.d.4.A. An existing septic tank may act an emergency holding tank.

4.6.d.4.B. In areas of frequent power outages of a duration of more than four hours each, the installation of emergency holding tanks of 200 gallons capacity is a requirement.

4.6.d.5. Sequence of Connections. The sequence of valves, pump, and other appurtenances from the residence to the collection force main shall be as follows: four-inch sewer line, gate valve, pump, check valve, gate valve, and connection line with 45-degree bend in the direction of flow.

4.6.d.6. Check and Gate Valves.

4.6.d.6.A. Check or gate valves shall be either plastic or bronze.

4.6.d.6.B. Check valves may be either swing check or ball type. If using swing type check valves, construction of a one- to two-foot horizontal run of straight pipe on the downstream side of the check valve is a requirement.

4.6.d.7. Level Controls. Level controls in the pump station shall be either mercury magnetic switches, mercury switches, or pressure switches.

4.6.e. Septic Tank Effluent Pressure Systems.

4.6.e.1. Location. Same as Submersible Pumps. See subdivision 4.4.d.of this rule.

4.6.e.2. Controls.

4.6.e.2.A. Control panels shall be NEMA type 3 or 4 enclosure.

4.6.e.2.B. The pump and float controls shall have provision for disconnection without entering the main control box.

4.6.e.3. Alarms. Same as Grinder Pump Pressure Systems. See paragraph 4.6.d.3. of this rule.

4.6.e.4. Sequence of Connections. The sequence of valves, pump, and other appurtenances from the residence to the collection force main shall be as follows: four-inch sewer line, septic tank, pumping chamber with pump, check valve, gate valve and connection to main collection line with 45- degree bend in direction of flow.

4.6.e.5. Check and Gate Valves. Same as paragraph 4.6.d.6. of this rule.

4.6.e.6. Level Controls. Same as paragraph 4.6.d.7. of this rule.

4.6.e.7. There shall be provisions for the treatment of septage at the plant. There shall be a provision for a septic tank pumping vehicle.

4.6.f. Maintenance and Operation.

4.6.f.1. In the interest of obtaining proper maintenance and operation on a pressure sewer system, the applicant shall be either:

4.6.f.1.A. Under the jurisdiction of a public entity;

4.6.f.1.B. Under the jurisdiction of a private company regulated by the public service commission; or

4.6.f.1.C. Under the jurisdiction of a property owners association.

4.6.f.2. Maintenance personnel employed by an entity operating a pressure system shall attend a factory training course on maintenance and operation of the proposed units.

4.6.f.3. For maintenance needs, this rule recommends a truck provided with a hoist.

4.6.f.4. This rule requires permanent maintenance easements if the location of the pumping equipment and other appurtenances is on private property.

4.6.f.5. An applicant shall keep spare parts, such as air relief valves, gate valves, and relay switches in inventory.

4.6.f.6. This rule does not allow mixing equipment (makes, models) for a specific project.

4.6.f.7. An applicant shall provide spare pumps in the initial design according to Table 64-47-D. at the end of this rule.

W. Va. Code R. § 64-47-4