[27 Pa.B. 5877]
[Continued from previous Web Page]
TABLE B
Soil Characteristics Slope Required Spray Field Area (Ft2) Depth To Rock Depth To Water Table 3 Bedroom Home Additional Area Per Bedroom 16 to 20 inches 10 to 40 inches <=12% 40,000 10,000 >=12% 80,000 20,000 >40 inches <=12% 15,000 3,750 >12% 30,000 7,500 >20 inches 10 to 20 inches <=12% 20,000 5,000 <=12% 40,000 10,000 >20 inches <=12% 10,000 2,500 >12% 20,000 5,000 § 73.17. Sewage flows.
(a) The flow figures in this subsection and subsection (b) are peak daily flows for the design of community onlot sewage systems. These flow figures are not intended to be used for the calculation of flows for the design of community sewerage systems or for the allocation of flows related to community sewerage systems. Design and permit sewage flows for a community sewerage system are to be calculated using the procedures established in the Department's ''Domestic Wastewater Facilities Manual.'' The sewage flow from single family dwellings served by a community onlot sewage system or from apartments, rooming houses, hotels and motels served byan individual or community sewage system shall be determined from the following table:
Type of Establishment Gallons/Unit/day Residential Gallons/unit
BOD/unit
Hotels and motels 100 .30 Multiple family dwellings and apartments, including townhouses, duplexes and condominiums 400 1.13 Rooming houses (per unit) 200 .60 Single family residences 400* .90 *For units of 3 bedrooms or less; for each bedroom over 3, add 100 gallons.
(b) The sewage flow, which shall exclude any industrial waste, for nonresidential establishments served by an individual or community sewage system shall be determined from the following table:
Type of Establishment Commercial Gallons/day BOD/day Airline catering (per meal served) 3 .03 * * * * * One licensed operator Beauty shops 200 -- Bus service areas not including food (per patron and employe) 5 .02 Country clubs not including food (per patron and employe) 30 .02 Drive-in theaters (not including food--per space) 10 .06 Factories and plants exclusive of industrial wastes (per employe) 35 .08 Laundries, self-service (gallons/washer) 400 2.00 Mobile home parks, independent (per space) 400 1.00 * * * * * Warehouses (per employe) 35 -- Work or construction camps (semipermanent) with flush toilets (per employe) 50 .17 Work or construction camps (semipermanent) without flush toilets (per employe) 35 .02 * * * * *
Churches (additional kitchen waste per meal served) 3 -- Churches (additional with paper service per meal served) 1.5 -- * * * * *
Schools, boarding (per resident) 100 .17 Schools, day (without cafeterias, gyms or showers per student and employe) 15 .04 Schools, day (with cafeterias, but no gym or showers per student and employe) 20 .08 Schools, day (with cafeterias, gym and showers per student and employe) 25 .10
Type of Establishment Recreational and Seasonal Gallons/day BOD/day * * * * *
Camps, hunting and summer residential (night and day) with limited plumbing including water-carried toilet wastes (per person) 50 .12 * * * * * Fairgrounds and parks, picnic--with bathhouses, showers, and flush toilets (per person) 15 .06 Fairgrounds and parks, picnic (toilet wastes only, per person) 5 .06 Swimming pools and bathhouses (per person) 10 .06 (c) Actual water meter or sewer meter flow data indicating peak daily flows different than those shown in this section over a 1-year period for a similar nonresidential establishment may be accepted for use in sizing the onlot disposal system. If average daily flows are used, the peak daily flow shall be calculated by multiplying the average daily flow by two.
(d) Establishments with food preparation facilities are required to install adequately designed pretreatment units and traps to reduce greases and biological oxygen demand (BOD) prior to discharge to an individual or community sewage system.
BUILDING SEWERS § 73.21. Specifications.
(a) Building sewers shall be constructed of a durable material acceptable to the Department or the local agency.
(b) The local agency may restrict the type of materials used by code, ordinance or resolution and shall notify the applicant when restrictions are imposed.
(c) When the average daily flow of sewage from an establishment is 1,000 gallons or less, building sewers shall be at least 3 inches in diameter unless otherwise specified by local plumbing or building codes. When the average daily flow exceeds 1,000 gallons per day, building sewers shall be at least 6 inches in diameter unless otherwise specified by local plumbing or building codes.
(d) Cleanouts shall be provided at the junction of the building drain and building sewer.
(e) Cleanouts shall be provided at intervals of not more than 100 feet.
(f) Bends ahead of the treatment tank shall be limited to 45° or less where possible. If 90° bends cannot be avoided, they shall be made with two 45° bends.
(g) The grade of the building sewer shall be at least 1/8 inch per foot; however, the grade of the 10 feet of building sewer immediately preceding the treatment tank may not exceed 1/4 inch per foot.
(h) Building sewers shall be constructed with watertight joints, shall be of sufficient strength to withstand imposed loads and installed on material suitable for preventing damage from settling.
(i) The building sewer shall be installed to allow continuous venting of the treatment tank through the main building stack unless otherwise specified by local plumbing or building codes.
(j) Building sewers shall be connected to treatment tanks by means of watertight mechanical seals or hydraulic grouting. Use of Portland cement grouting is not permitted.
TREATMENT TANKS § 73.31. Standards for septic tanks.
(a) Capacity.
(1) The minimum liquid septic tank capacity for any installation is 900 gallons.
(2) For single-family dwelling units, not served by a community onlot system, a minimum daily flow of 400 gpd shall be used to determine required septic tank capacity. This figure shall be increased by 100 gallons for each additional bedroom over three. The daily flow indicated provides for use of garbage grinders, automatic washing machines, dishwashers and water softeners.
(3) The minimum septic tank capacity shall be calculated from the following table using estimated sewage flows from paragraph (2), or § 73.17(a)--(c) (relating to sewage flows):
Design flow Tank capacity (gallons per day) (gallons) 0--500 (3.5 x flow exceeding 400 gpd) + (900) 500--5,000 (1.50 x flow exceeding 500 gpd) + (1,250) 5,000--7,500 (1.45 x flow exceeding 5,000 gpd) + (8,000) 7,500--10,000 (1.35 x flow exceeding 7,500 gpd) + (11,625) over 10,000 (1.50 x the daily flow) Note: Septic tanks may be connected in series to attain required capacity.
(b) Construction.
(1) Tanks shall be watertight and constructed of sound and durable material not subject to excessive corrosion or decay.
(i) Precast concrete tanks shall have a minimum wall thickness of 2 1/2 inches and be adequately reinforced.
(ii) Precast slabs used as covers shall have a thickness of at least 3 inches and be adequately reinforced.
(iii) Tanks having a liquid capacity of 5,000 gallons or less may not be constructed of blocks, bricks or similar masonry construction.
(iv) Tanks having a capacity in excess of 5,000 gallons may be constructed onsite to meet the standards of the National Concrete Masonry Association for reinforcement and waterproofing as listed in the most recent edition of its publication ''Concrete Masonry Foundation Walls,'' copyright 1957 NCMA.
(v) Steel tanks shall meet United States Department of Commerce Standards 177-62.
(2) The depth of liquid in any tank or its compartments shall be:
(i) Not less than 2 1/2 nor more than 5 feet for tanks having a liquid capacity of 600 gallons or less.
(ii) Not less than 3 feet nor more than 7 feet for tanks having a liquid capacity of more than 600 gallons.
(3) No tank or compartment may have an inside horizontal dimension less than 36 inches.
(4) Septic tank installations may consist of tanks with multiple compartments or multiple tanks. The first compartment or tank shall have at least the same capacity as the second but may not exceed twice the capacity of the second. Tanks or compartments shall be connected in series and may not exceed four in number in any one installation.
(c) Inlet and outlet connections.
(1) The bottom of the inlet shall be a minimum of 3 inches above the bottom of the outlet.
(2) Inlet baffles or vented tees shall extend below the liquid level at least 6 inches. Penetration of the inlet device may not exceed that of the outlet device.
(3) The outlet baffles or vented tees of each tank or compartment shall extend below the liquid surface to a distance equal to 40% of the liquid depth. Penetration of outlet baffles or tees in horizontal cylindrical tanks shall be equal to 35% of the liquid depth.
(4) The inlet and outlet baffles or vented tees shall extend above liquid depth to approximately 1 inch from the top of the tank. Venting shall be provided between compartments and each tank.
(5) The outlet baffles or vented tees of the last compartment or tank shall be equipped with a solids retainer.
(d) Treatment tank access.
(1) Access to each tank or compartment of the tank shall be provided by a manhole with an inside dimension of at least 20 inches square (20 × 20) or in diameter, with a removable cover. The top of the tank containing the manhole or the top of a manhole extension may not be more than 12 inches below grade level. If access is extended to grade, the access cover shall be airtight. Grade level access covers shall be secured by bolts or locking mechanisms, or have sufficient weight to prevent unauthorized access.
(2) The ground shall slope away from any access extended to grade level.
(e) Inspection port. A maximum 4-inch diameter inspection port with sealed cover shall be installed to grade level above the inlet tee.
§ 73.32. Standards for aerobic treatment tanks.
(a) Capacity shall comply with the following:
(1) The rated treatment capacity of an aerobic treatment tank shall be specified by the manufacturer. The manufacturer's data shall be in conformance with the approved test sequence and protocol in subsection (b).
(2) The minimum manufacturer's rated treatment capacity of an aerobic treatment tank approved under this section is 400 gallons per day.
(3) For single family dwelling units not served by a community system, a minimum daily flow of 400 gpd shall be used to determine required aerobic tank capacity. This figure shall be increased by 100 gallons for each additional bedroom over three. The daily flow indicated provides for use of garbage grinders, automatic washing machines, dishwashers and water softeners.
(4) For all other installations, the rated treatment capacity shall meet or exceed the estimated daily sewage flow as determined from § 73.17(a), (b) or (c) (relating to sewage flows).
(b) Testing and approval shall comply with the following:
(1) Aerobic treatment tanks serving single family dwellings, or establishments, with flows of 1,500 gpd or less shall bear the seal of the NSF indicating testing and approval by that agency under Standard No. 40.
(2) Units tested and awarded a seal under other than the current standard shall be approved for use until expiration of the seal. Units initially submitted for testing or resubmitted for testing shall be approved under the version of Standard No. 40 in effect at that time.
(3) Aerobic treatment tanks serving establishments with flows exceeding 1,500 gpd shall have either:
(i) NSF certification under Criteria C-9.
(ii) Performance data certified by NSF under the provisions of that agency's Standard Performance Evaluation Method.
(c) The Department will provide local agencies with a current list of aerobic sewage treatment tanks that have been found to be in conformance with the Department's standard.
(d) Multiple aerobic treatment tanks connected for the purpose of achieving required hydraulic capacity shall only be permitted where the tanks are connected by parallel. All tanks shall have equal capacity and receive equal loading.
(e) Every aerobic sewage treatment tank shall be equipped with a visual and audible alarm system which shall be designed to respond to any electrical or mechanical failure or malfunction of the tank or any component thereof.
DOSING AND DISTRIBUTION REQUIREMENTS § 73.41. General.
Effluent from the treatment tank shall be discharged to the dosing tank, to the distribution box or directly to the absorption area through a watertight line a minimum of 3 inches in diameter unless otherwise specified by local plumbing or building codes. All lines shall be placed on a minimum grade of at least 1/4 inch per foot, sloping away from the treatment tank. If a distribution box is used, the lines from that box to the laterals shall meet the same standard. If a free access sand filter or buried sand filter is used, the lines from the treatment tank to the pump station and the filter tank to a lift station or chlorine contact tank or storage tank shall meet the standards of this section. Connections of lines to tanks and distribution boxes shall be made using water tight mechanical seals or hydraulic grouting. Use of Portland cement grouting material is not permitted.
§ 73.42. Gravity distribution.
(a) Gravity distribution may be used in all instances, except where prohibited by § 73.43 (relating to pressurized distribution).
(b) The distribution system shall be arranged to provide for uniform distribution of the effluent.
(c) The flow shall be equally divided between individual laterals of a trench system or between seepage beds by use of a distribution box.
(d) The flow shall be divided between individual laterals in a seepage bed by a distribution box or by an unperforated pipe header connecting all laterals within the bed. Where distribution is by means of an unperforated pipe header, the terminal ends of all individual laterals shall also be connected with unperforated pipe.
(e) Distribution boxes shall comply with the following:
(1) When a distribution box is used, it shall be installed level to provide equal distribution of treatment tank effluent to each line. For testing purposes, the person responsible for the installation shall provide an adequate amount of water to check the level of the inlet and outlet lines.
(2) Construction shall comply with the following:
(i) Distribution boxes shall have removable covers.
(ii) Each lateral shall be connected separately to the distribution box.
(iii) The bottom of all outlets shall be at the same elevation, and the bottom of the inlet shall be at least 1 inch above the bottom of the outlet. The bottom of the outlet shall be at least 4 inches above the bottom of the distribution box.
(iv) Baffles shall comply with the following:
(A) A baffle shall be installed in the distribution box in the event that treatment tank effluent is discharged to the distribution box by a pump or siphon.
(B) The baffle shall be perpendicular to the inlet, be secured to the bottom of the box and extend vertically to a point level with the crown of the inlet pipe.
(v) A tee or elbow directed toward the bottom of the distribution box may be substituted for the baffle required by subparagraph (iv).
(3) Distribution boxes shall be installed on an adequate base of undisturbed or properly compacted earth or aggregate outside of the absorption area. Lightweight nonconcrete distribution boxes shall be anchored or otherwise secured to prevent shifting after installation. Adjustable distribution box weirs may be used on the outlet of the box.
(f) Laterals shall be a minimum of 3 inches in diameter unless a larger diameter is specified by local plumbing or building codes. Bends used in the disposal field shall be made with standard fittings.
(g) The maximum length of individual laterals employing gravity distribution is 100 feet.
§ 73.43. Pressurized distribution.
Pressurized distribution is required in the following instances:
(1) All elevated sand mounds.
(2) When the percolation rate exceeds 60 minute/inch.
(3) All systems having a total absorption area in excess of 2,500 square feet.
(4) Individual residential spray irrigation system spray fields and buried sand filters.
§ 73.44. Pressurized distribution design.
(a) General requirements are as follows:
(1) The piping used in a pressurized effluent system shall have watertight joints.
(2) Systems using pressure distribution shall meet the general requirements of §§ 73.52, 73.53, 73.55, and 73.166.
(3) Delivery pipes from dosing pumps shall be installed to facilitate drainage of the distribution piping back to the dosing tank between doses.
(b) Seepage beds of 2,500 square feet or less shall meet the following design standards.
(1) Conveyance of effluent from the dosing tank to the absorption area shall be through a delivery pipe sized to minimize friction loss. Check valves shall be prohibited on delivery pipes. Where the system designer determines that water hammer may be a problem, thrust blocks may be installed on delivery pipes.
(2) When equally sized absorption areas are dosed simultaneously, a header pipe shall be used to connect the delivery pipe from the tank to the manifolds. The header pipe shall be sized to minimize friction loss. Effluent application rates per square foot of absorption areas served by a common header shall have a maximum design variation of 10%. If the distance from the treatment tank to the absorption area would cause excessive backflow into the dosing tank, a transfer tank may be used between the treatment tank or storage tank and dosing tank.
(3) Distribution of effluent to the individual laterals shall be by a central manifold extending into the absorption area from the delivery pipe or header. The manifold shall have the following minimum diameters:
Sq. ft. of Absorption Area Minimum Manifold Diameter 200 to 1,199 1 1/2" 1,200 to 2,500 2" (4) Laterals shall be extended from both sides of the manifold by opposing tees or a double sanitary tee.
(5) Laterals shall consist of 1 1/2 inch diameter pipe, with holes placed along the bottom of the pipe; an end cap shall be cemented on the terminal end of the lateral. Minimum hole size shall be 1/4 inch.
(6) The first hole in the lateral shall be 3 feet from the manifold. Additional holes shall be placed 6 feet on center with the last hole placed directly in the end cap.
(7) The maximum length of a lateral from the manifold to the end cap shall be 51 feet and contain nine holes.
(8) The location and spacing of the laterals shall conform to § 73.53(3)--(6) (relating to seepage beds).
(9) Opposing laterals may not differ in length by more than 6 feet.
(10) When less than the maximum length of lateral is used, as described in paragraph (7), the lateral shall be shortened in 6-foot sections with hole spacing maintained as required in paragraph (6).
(11) All systems shall be designed to maintain a minimum of 3 feet of head at the terminal end of each lateral.
(12) The minimum pump capacity (gpm) shall be calculated by multiplying the total number of discharge holes contained in the laterals of a proposed distribution layout by the gpm factor determined by the hole size at the design head level.
(13) Total pump head shall be calculated by addition of all losses incurred due to elevation changes, pipe and fitting friction losses, and the head level to be maintained at the terminal end of the lateral as specified in paragraph (11).
(14) For purposes of calculating head loss due to friction, head loss in the standard lateral as described in paragraph (7) shall be assumed to be 0. Head loss due to friction in pipe and fittings used in construction of the pressure system shall be calculated using a friction loss table for smooth-walled plastic pipe (C=150).
(15) When siphons are used in a pressure distribution system, each discharge hole shall be at least 5/16 inch in diameter. The discharge from all of the holes in the distribution system may not be less than the minimum rate of the siphon and may not vary from the average discharge rate of the siphon by more than 20%.
(c) Seepage beds of greater than 2,500 square feet shall meet the following design standards:
(1) The diameter of individual laterals, size and spacing of discharge holes, and minimum diameter of the distribution manifold may not be restricted by subsection (b) except that no discharge hole may be less than 1/4 inch for systems using pumps or 5/16 inch for systems using siphons.
(2) The maximum length of a lateral designed under this subsection or subsection (d) shall be 100 feet.
(3) Discharge rates from the individual holes of the lateral at design head shall be calculated using the sharp-edged discharge hole equation: gpm=11.82(d2) (Eh)
gpm=gallons per minute
(d)=diameter of hole (inches)
(h)=head to be maintained at the terminal ends of the lateral (in feet).
(4) All piping and fittings in the system shall be sized to minimize friction losses to provide as uniform distribution of effluent as possible.
(5) The design head at the terminal end of the last lateral shall be at least 3 feet.
(6) The head loss due to friction from the beginning of the distribution manifold to the terminal end of the last lateral may not exceed 15% of the head level to be maintained at the terminal end of the lateral.
(7) Spacing of laterals and discharge holes in the laterals shall provide for uniform distribution of the effluent over the seepage bed.
(8) The arrangement of laterals and discharge holes shall result in the discharge holes being spaced at the apexes of either squares or equilateral triangles.
(i) The maximum spacing between discharge holes shall be 10 feet where an equilateral triangle pattern is utilized.
(ii) The maximum spacing between discharge holes shall be 8 feet where a square pattern it utilized.
(9) The minimum pump capacity shall equal the total discharge from all holes in the laterals when operating at designed head.
(10) The permittee shall conduct a test pressurization of the completed distribution system in the presence of the sewage enforcement officer prior to covering the piping system from view. During the test, the permittee shall confirm that all joints are watertight and that a discharge is occurring from each hole.
(d) Design of pressure distribution in trenches shall comply with the following:
(1) Subsection (c)(1)--(4) and (10) applies to design of trenches utilizing pressurized effluent distribution.
(2) Variation in head in the laterals caused by differences in elevation or friction losses shall be compensated for by individual design of the laterals.
(3) The effluent application rate per square foot of any two trenches served by a common dosing tank shall have a maximum design variation of 10%.
(4) Equalization of loading may be accomplished by variation of discharge hole diameter between trenches, variation of spacing of discharge holes between trenches or another method approved by the Department or sewage enforcement officer.
(5) The maximum spacing between discharge holes is 10 feet.
(6) The manifold for a trench system shall be placed on undisturbed soil a minimum of 6 inches above the trench bottom.
(7) A minimum isolation distance of 3 feet shall be maintained between the manifold and the beginning of any trench. The individual laterals in the trench shall be connected to the manifold using unperforated pipe. The area beneath the manifold and connecting pipe shall consist of undisturbed or compacted soil.
(8) The design head at the terminal end of each lateral shall be at least 3 feet.
§ 73.45. Dosing tanks.
Dosing tanks shall be constructed to the following specifications:
(1) Dosing tanks shall be constructed of materials to the specifications outlined in § 73.31(b) (relating to standards for septic tanks).
(2) For all systems other than individual residential spray irrigation systems, the dosing tank shall be designed so that the estimated daily flow shall be discharged to the absorption area in one or more doses. Minimum dose volume shall be five times the internal liquid capacity of the delivery pipe, manifold and laterals, or 100 gallons, whichever is greater. When a siphon is used in a pressure distribution system, the minimum dose volume shall be equal to the internal liquid capacity of the delivery line plus five times the internal liquid capacity of the manifold and laterals.
(3) The dosing tank shall have a minimum liquid capacity equal to or greater than two times the designed dose volume.
(4) Sufficient space shall be provided for electrical connections and proper pump control operation.
(5) Unless otherwise regulated by local electrical codes, all electrical connections shall be moisture resistant and at a point higher than the inlet pipe, or mounted above grade outside of the dosing tank or manhole extension within a tamper resistant, lockable control box.
(6) A watertight manhole, at least 20 inches square or 24 inches in diameter, extended to grade, shall be provided for access to the dosing tank. Manhole covers shall meet the specifications of § 73.31(d).
§ 73.46. Dosing pumps, siphons and lift pumps.
(a) Dosing pumps for all onlot sewage disposal systems except individual residential spray irrigation systems shall meet the following specifications:
(1) The pump shall be sized to deliver a flow in gpm equal to or greater than the combined flows from all discharge holes in the laterals when operating at designed level of head and shall be rated by the manufacturer for handling of sewage effluent.
(2) The intake of the dosing pump shall be at least 6 inches from the bottom of the tank. The intake of any dosing pump shall be at a lower elevation than the lowest lateral.
(3) Pumps may not be suspended above the bottom of the tank by chains or similar equipment.
(4) A disconnect shall be incorporated into the piping within the dosing tank for ease of pump removal.
(5) An effective warning device, as described in § 73.62(c) (relating to standards for holding tanks), shall be installed in the dosing tank to indicate failure of the pump or siphon. Electrically operated warning systems shall be on a circuit and breaker separate from the pump.
(6) A siphon or other discharge mechanism may be substituted for a pump where site conditions permit the use of a gravity flow device, if the average discharge rate of the device meets the requirements of paragraph (1).
(7) A copy of the performance curve of the pump or discharge specifications for the siphon to be used shall be attached to the system design. A copy of the manufacturer's specification showing that the pump is designed to handle sewage or sewage effluent shall also be attached to the system design.
(8) When an aeration tank is used which results in a periodic pump discharge from the treatment tank, the discharge mechanism may be substituted for a dosing tank and pump if the periodic discharge rate meets the criteria in subsections (a)(1) and (b)(2) and § 73.45(2) (relating to dosing tanks).
(9) Pumps or siphons serving systems having total absorption areas greater than 2,500 square feet shall have a minimum discharge capacity at least two times the estimated peak flow for the facility served.
(10) When an establishment produces more than 50% of its total daily flow during a peak flow period, the minimum dose volume shall equal the anticipated flow during the peak period.
(11) Pumps employed for the purpose of lifting effluent to a higher elevation may not be deemed dosing pumps when the system does not meet the criteria of § 73.43 (relating to pressurized distribution). Pumps for this purpose shall have a discharge capacity at least two times the estimated peak flow of the facility served when operating at designed level of head, but at least 5 gpm and shall be rated by the manufacturer for handling sewage effluent.
(12) Siphon discharge lines shall be equipped with an observation port. The access to the observation port shall be extended to grade, capped and secured to prevent unauthorized entry.
(b) Lift pumps shall meet the following specifications:
(1) Meet the standards in subsection (a)(1)--(5), (7) and (8).
(2) Be designed to discharge a minimum flood dose of 2 inches over the sand surface.
(c) Dosing pumps used to pressurize a spray field distribution system shall be designed in accordance with the specifications in subsection (a)(1)--(5) and (7).
CONSTRUCTION OF ABSORPTION AREAS § 73.51. General.
(a) In all systems, if an absorption area is proposed, the top of the limiting zone shall be at least 4 feet below the bottom of the aggregate. Coarse aggregate used in the distribution system shall meet the requirements of the Department of Transportation specifications, Publication #408, section 703. The size and grading of the aggregate shall meet AASHTO No. 57 requirements from a PADOT certified stockpile and shall be of Type B quality requirements.
(1) Where the depth to the top of the limiting zone is 60 inches or greater, the system shall be installed so that the bottom of the aggregate is a minimum of 4 feet above the limiting zone.
(2) Where the depth to the top of the limiting zone is less than 60 inches, an elevated sand mound is required. Isolation from the limiting zone shall be achieved as required by § 73.55(a)(3)--(5) (relating to elevated sand mounds).
(3) An absorption area may not be installed where less than 20 inches of suitable undisturbed mineral soil exists.
(4) When infiltration chambers or other devices which require no aggregate are used, adequate provisions to protect the infiltrative surfaces from damage by operation of pressure distribution systems shall be made.
(b) Before and after installation, equipment and vehicles shall be kept off the proposed absorption area, including the downslope area, to prevent undue compaction of the soil. Care shall be exercised during construction to prevent undue compaction and damage to the system and the downslope area.
(c) Soil moisture levels during construction of the absorption area shall be such that a sample of natural mineral soil taken from the level of the proposed installation will crumble if compressed into a ball.
§ 73.52. Standard trenches.
(a) Design. The maximum slope of the undisturbed soil of a proposed absorption area where a trench system may be permitted is 25%.
(1) For slopes between 15% and 25%, detailed design in relationship to elevation shall be provided.
The designer shall inspect the installation and verify that, to the best of his knowledge and belief, the system was installed in accordance with the plans and specifications. Copies of the plans and specifications and the designer's report are to be attached to the applicant's copy, sewage enforcement officer's copy and the Department's copy of the application for sewage permit.
(b) Construction. Trenches in an absorption area shall be constructed in accordance with the following:
(1) There shall be a minimum of two trenches per field.
(2) Trenches shall follow approximately the ground surface contours so that variations in trench depth shall be minimized.
(3) There shall be at least 6 feet of soil between the treatment tank or dosing tank and the nearest trench.
(4) The width of the bottom of the individual trench shall be 12 to 72 inches.
(5) The depth to the bottom of the absorption area shall be 12 to 36 inches.
(6) The bottom of the absorption area shall be level to a tolerance of 2 inches per 100 feet.
(7) The minimum width of undisturbed earth between trenches shall be 5 feet. When elevated sand mound trenches are used, the distance between trenches shall be measured from the toe of the sand of each trench.
(8) The minimum depth of aggregate material under laterals shall be 6 inches.
(9) Laterals shall be placed in the center of the trench. The first or last discharge hole of a lateral may be no more than 5 feet nor less than 2 feet from the ends of the trench.
(10) Laterals shall be level to a maximum tolerance of 4 inches of fall per 100 feet toward the terminal end of the lateral.
(11) The minimum depth of aggregate material over the laterals shall be 2 inches.
(12) The depth of aggregate shall be uniform throughout the absorption area.
(13) The top of the aggregate material shall be covered with geotextile fabric, untreated building paper or a 2-inch layer of hay, straw or similar material to prevent backfill material from settling into the aggregate.
(14) The minimum depth of earth cover over the aggregate in all installations shall be 12 inches. Where the top of the aggregate is less than 12 inches from the undisturbed soil surface, the soil cover shall extend beyond the absorption area by at least 3 feet on all sides.
(15) The backfill material shall consist of soil suitable for the growth of vegetation, and be seeded to control erosion.
(16) Trench laterals shall be fitted with end caps.
§ 73.53. Seepage beds.
Whenever seepage beds are employed, they shall meet the requirements of § 73.52(b)(5), (6), (8) and (10)--(16) (relating to standard trenches) in addition to the following specifications:
(1) The maximum slope of the undisturbed soil of a proposed absorption area where a seepage bed may be permitted is 8.0%.
(2) The required absorption area may be provided by one or more seepage beds:
(i) The individual beds of a single onlot system shall be separated by a minimum of 5 feet.
(ii) When elevated sand mound beds are used, the distance between beds shall be measured from the toe of the sand of each bed.
(3) The bed shall contain a minimum of two laterals or two opposing sets of laterals when pressure distribution is used.
(4) Laterals shall be equally spaced a maximum of 6 feet on center, except as provided in § 73.44(c)(8) (relating to pressurized distribution design).
(5) Laterals shall be placed no further than 5 feet nor less than 2 feet from the sidewalls of the bed.
(6) Laterals shall be placed in the bed so that the first and last discharge holes may be no more than 5 feet nor less than 2 feet from the ends of the bed.
§ 73.54. Subsurface sand filter beds and trenches.
(a) General. Subsurface sand filters without underdrains shall meet the following criteria:
(1) Subsurface sand filters may not be utilized on soils where the limiting zone occurs at less than 6 feet below the mineral soil surface.
(2) The average percolation rate, as determined by § 73.15 (relating to percolation tests), shall be greater than 90 minutes per inch.
(3) The average percolation rate at a depth between 36 and 60 inches shall be within the range of 3--90 minutes per inch.
(4) The average percolation rate obtained from paragraph (3) shall be applied to § 73.16(c) (relating to absorption area requirements) for determination of the absorption area and other system requirements.
(5) System design shall meet the requirements of § 73.52 (relating to standard trenches) or § 73.53 (relating to seepage beds) except as modified by subsection (b).
(b) Construction. Subsurface sand filters shall be constructed as follows:
(1) The maximum depth of the excavation shall be 5 feet.
(2) Sand meeting the specifications of § 73.55(c) (relating to sand specifications) shall be placed in the entire bed or trench to a minimum depth of 12 inches.
§ 73.55. Elevated sand mounds.
(a) Design.
(1) The maximum slope of the undisturbed soil, to the extremities of the berm, of a proposed absorption area where elevated sand mound trenches may be permitted is 12%.
(2) The maximum slope of the undisturbed soil, to the extremities of the berm, of a proposed absorption area where an elevated sand mound bed may be permitted is 12%.
(3) The limiting zone is the base elevation for measuring the required depth of sand to achieve a minimum of 4 feet of satisfactory material between the bottom of the aggregate and the top of the limiting zone.
(4) A minimum of 1 foot of sand shall be placed under the aggregate in all elevated sand mound systems.
(5) Existing mineral soil shall be utilized. No mineral soil in the area of the elevated sand mound may be removed or disturbed for the purpose of adding or mixing fill material.
(6) Elevated sand mound trenches shall meet the requirements of § 73.52(b) (relating to standard trenches) and this section.
(7) Elevated sand mound beds on slopes up to 8% shall meet the requirements of § 73.53 (relating to seepage beds) and subsection (b). Other sand mound beds shall comply with subsection (d).
(b) Construction.
(1) Vegetation shall be cut close to the ground throughout the area to be utilized for the absorption area and berm. Bushes and trees shall be cut flush with the ground surface; roots shall be left in place. Cut vegetation or organic litter shall be raked and removed from the absorption and berm areas.
(2) The proposed absorption area not obstructed by stumps or other obstacles shall be roughed or plowed parallel with the contour to a maximum depth of 6 inches, using a multiple share chisel plow or similar implement attached to light-weight equipment. Rotary tilling is prohibited.
(3) Under no circumstances may equipment travel on the plowed soil surface until the sand is in place.
(4) Immediately after plowing, sand shall be placed over the exposed plowed surface. Sand shall be placed from the upslope side of the bed using only lightweight equipment.
(5) The slope of the sand not directly beneath the aggregate area shall be approximately 50%.
(6) The top of the sand directly beneath the aggregate shall be level to a tolerance of +2 inches per 100 feet.
(7) The mound shall be surrounded by a berm consisting of mineral soil containing less than 20% coarse fragments with no coarse fragments greater than 4 inches in diameter, more stable and less permeable than the sand, and lightly compacted during construction to contain and protect the mound interior. The width of this berm shall be a minimum of 3 feet at the top of the aggregate.
(8) Upon completion, the outside slope of the berm may be no greater than 50% and shall be seeded to assure the stability of the berm. The cover over the aggregate shall be a minimum of 1 foot of soil suitable for the growth of vegetation.
(9) No equipment may be permitted on the downslope side of the mound with the exception of lightweight equipment that is used to form the downslope berm. To the greatest extent possible, aggregate and the cover material shall be placed from the upslope side of the mound.
(10) When a mound system with trenches is used, the area between the individual trenches shall be filled with mineral soil. A minimum distance of 5 feet shall separate sand of individual trenches. This measurement shall be from the toe of the sand.
(11) The area surrounding the mound shall be grated to provide for diversion of surface runoff waters.
(c) Sand. Sand suppliers shall provide certification in writing to the sewage enforcement officer and permittee, with the first delivery to the job site from every sand source listing the amount of sand delivered, and that all sand supplied meets the requirements posted in the Department of Transportation specifications Publication #408, section 703. The size and grading shall meet bituminous concrete sand Type B #1 or #3 requirements from a Department of Transportation certified stockpile. The sieve analysis shall be conducted in accordance with PTM #616 and #100.
(d) Elevated sand mound beds. Elevated sand mound beds on slopes greater than 8% shall meet the requirements of § 73.53 and subsection (b). In addition, the following apply:
(1) The absorption area shall have a minimum length to width radio of 4 to 1.
(2) The long axis of the absorption area shall be perpendicular to the slope. The bed construction shall follow the ground surface contours.
(3) Upon completion, the outside slope of the berm may be no greater than 33.3%.
(4) Designing the location of multiple absorption areas so that one absorption area is placed hydraulically upgradient or downgradient from the other may cause the lower absorption area to fail because of excessive hydraulic loading from the upper absorption area. Unless the potential for an impact is shown to be nonexistent by the applicant through the alternative/experimental system process, this type of absorption area placement is prohibited.
RETAINING TANKS § 73.62. Standards for holding tanks.
(a) A holding tank shall be constructed to meet the specifications of § 73.31(b)(1) (relating to standards for septic tanks).
(b) The minimum capacity of a holding tank is 1,000 gallons or a volume equal to the quantity of waste generated in 3 days, whichever is larger.
(c) The holding tank shall be equipped with a warning device to indicate when the tank is filled to within 75% of its capacity. The warning device shall create an audible and visual signal at a location frequented by the homeowner or responsible individual.
(d) Disposal of waste from a holding tank shall be at a site approved by the Department.
§ 73.64. Chemical toilet or other portable toilet.
(a) When proposed for use at temporary construction sites, facilities providing temporary recreational or sporting activities (such as a special event) or temporary seasonal facilities other than those intended for human habitation, chemical toilets or other portable toilets may be exempt from the onlot permitting requirements of Chapter 72 (relating to administration of sewage facilities permitting program) at the discretion of the local agency but improper installation or maintenance of these toilets shall constitute a nuisance under section 14 of the act (35 P. S. § 750.14) and be enforceable by the local agency.
(b) If multiple chemical toilets or other portable toilets are proposed for temporary use at construction sites, recreational activities or seasonal facilities, all units proposed for installation shall be included under one permit.
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