1993 Specifications CSJ s 3136-01-126, etc. & 0683-01-070, etc. SPECIAL SPECIFICATION 3504 Septic Tank System 1. Description. This Item shall govern for all materials, equipment and labor necessary for the installation of Septic Tank System and all associated piping, fittings and appurtenances. Installation of the Septic Tank System shall be conducted by a qualified licensed system installation Contractor. The Contractor shall comply with the requirements of all laws, ordinances, rules and regulations of federal, state and local authorities. The Contractor shall provide documentation, which is acceptable to the Engineer, that they are experienced and qualified in Septic Tank System installation. All personnel shall be trained and experienced in the system installation practices and safety precautions. 2. Materials. (1) Summary. (a) This Section includes sewage disposal systems consisting of the following: 1. Concrete septic tanks and manholes. 2. Septic tank filters. 3. Automatic sump pumps. 4. Control panels. 5. Distribution pipes and fittings. 6. Leaching pipes and fittings. 7. Absorption trench fill materials. 8. Absorption field materials. 9. Valves. (b) Refer to Sections included in the Special Specification, Toll Plaza Facility : 1. Division 15 Section Sanitary Waste and Vent Piping for sewer piping from buildings and structures to septic tank system. 2. Division 15 Section Sump Pump for sewage pumps selected for distribution to absorption fields. (2) Definitions. (a) Absorption Field. Subsurface wastewater disposal process. (b) Absorption Trench. System of leaching pipes and filtering materials installed in trenches for wastewater disposal. 1-7 3504
(c) Distribution Piping. Solid pipe and pipe fittings installed with tight joints between septic tank and other septic tank system structures to, but not including, leaching piping. (d) Leaching Piping. Perforated pipe and pipe fittings or plain pipe with open joints in absorption field. (e) PVC. Polyvinyl chloride. (3) Submittals. (a) Product Data. Include construction details, material descriptions, dimensions of individual components and profiles, and finishes as specified on the plans for the following: 1. Concrete septic tanks and manholes. 2. Septic tank filters. 3. Automatic sump pumps. 4. Control panels. 5. Distribution pipes and fittings. 6. Leaching pipes and fittings. 7. Absorption trench fill materials. 8. Absorption field materials. 9. Valves. (b) Shop Drawings. Include manhole openings, covers, pipe connections, and accessories for the following precast, reinforced-concrete structures: 1. Concrete septic tank. 2. Concrete manholes. (c) Coordination Drawings. Show piping, underground structures, and other utilities. Indicate size and invert elevations of piping and structures. (d) Permits. Contractor shall submit an approved On-Site Sewage Facility (OSSF) permit from Williamson County and Cities Health District. (4) Project Conditions. 3. Products. (a) Existing Utilities. Do not interrupt utilities serving facilities occupied by Owner or others unless permitted under the following conditions and then only after arranging to provide temporary utility services according to requirements indicated: 1. Notify Engineer not less than two days in advance of proposed utility interruptions. 2. Do not proceed with utility interruptions without Engineer's written permission. (1) Precast Concrete Septic Tanks and Manholes. (a) Description. Septic tank, 1500 gallon three-compartment tank with a 400-gallon first compartment, 600 gallon second compartment and 500 gallon pump chamber, precast reinforced-concrete tank and covers, designed for structural loading 2-7 3504
according to ASTM C 890 and made according to ASTM C 1227, or as described on the plans, or as directed by the Engineer. (b) Description. Manhole, precast reinforced-concrete sections according to ASTM C478, or as specified on the plans, with approved ring and cover. Include manhole over each septic tank compartment top as directed by the Engineer. (c) Inlet and Outlet Access. 15-in. diameter as described on the plans or as directed by the Engineer. (d) Backfill. Select backfill type III fill, or 3/8 in. washed river pea gravel, or as shown on the plans, or as directed by the Engineer. (2) Septic Tank Filters. (a) Description. Septic tank outlet filters, removable filter that restricts discharge solids to specified size and has access from surface for service. Zabel A-1801 Filter or approved equal. (3) Automatic Sump Pumps. (a) Description. Automatic submersible effluent pump. Barnes SP-33 0.3 hp Pump or approved equal. (b) Unit Size. Same as tank outlet pipe size, unless otherwise indicated. (4) Control Panels. (a) Description. Control panel with audio/visual high water alarm, separated fused disconnect for alarm circuit and pump circuit. GP-2115 control panel or approved equal. Properly mounted to pressure treated pole or to building. (5) Distribution Pipes and Fittings. (a) Refer to Special Specification, Toll Plaza Facility Division 15 Sanitary Waste and Vent Piping, Part 3 Execution Article for identification of systems where piping materials specified below are used. (b) PVC Sewer Pipe and Fittings. ASTM D 3034, SDR 26, non-perforated, for solvent-cement or elastomeric gasket joints. 1. Solvent Cement. ASTM D 2564. 2. Gaskets. ASTM F 477, elastomeric seal. (6) Leaching Pipes and Fittings. (a) Refer to Special Specification, Toll Plaza Facility Division 15 Sanitary Waste and Vent Piping, Part 3 Execution Article for identification of systems where piping materials specified below are used. (b) PVC Sewer Pipe and Fittings. ASTM D 2729, perforated, for solvent-cement joints. 1. Solvent Cement. ASTM D 2564. 3-7 3504
(c) Non-Vehicular-Traffic-Area Cleanouts. PVC pipe and fittings, ASTM D 3034, SDR 26, nonperforated, for solvent-cement or elastomeric gasket joints. Include PVC threaded cleanout plug. (d) Vehicular-Traffic-Area Cleanouts. ASME A112.36.2M; with round, flanged, cast-iron housing and secured, scoriated, medium-duty loading class, cast-iron cover. Include cast-iron ferrule and countersunk brass cleanout plug. (7) Absorption Trench Fill Materials. (a) Filtering Material. 3/8 to 1 in. of one uniform size of washed crushed stone, or 3/8 in. washed river pea gravel, or as directed by the Engineer. (b) Filter Mat. Geotextile woven or spun filter fabric, in 1 or more layers, for minimum total unit weight of 3 oz./sq. yd. (8) Absorption Field Materials. (a) Fill Material. 6 to 8 in. of sandy loam, or as shown on the plans, or as directed by the Engineer. (b) Vegetation Cover. Seed or hydromulch with perennial grasses or a mixed variety as described under Item 164 Seeding for Erosion Control, or as shown on the plans, or as directed by the Engineer. No shrubs or trees. (9) Valves. 4. Execution. (a) Description. 2 in. brass gate valve with 6 in. PVC valve box and cover, or as shown on the plans, or as directed by the Engineer. (b) Description. 1-1/4 in. pressure adjustment valve, or as shown on the plans, or as directed by the Engineer. (1) Examination. (a) Survey the area for septic tank system installation. Locate and mark existing utilities, underground structures, and aboveground obstructions before beginning and avoid disruption of and damage to services. (b) Examine soil structure, materials, and conditions. (c) Proceed with installation only after unsatisfactory conditions have been corrected. (2) Preparation. (a) Clean exposed surfaces of tanks and other structures and protect as necessary to ensure freedom from damage and deterioration at time of Substantial Completion. (3) Earthwork. 4-7 3504
(a) Excavating, Trenching, and Backfilling for Distribution Pipes and Fittings are specified in Item 400, Excavation and Backfill for Structures : 1. Stockpile topsoil for possible reuse in finish grading without intermixing with other excavated material. Stockpile materials away from edge of excavation and do not store within drip line of remaining trees. 2. Backfill with approved materials in a manner approved by the Engineer. 3. Place, grade, and shape stockpiles to drain surface water. Cover to prevent windblown dust. (b) Excavating and Backfilling for Septic Tanks are specified in Item 400, Excavation and Backfill for Structures : 1. Excavate sufficient width and length for tanks to a depth determined by tank inlet and outlet elevations. Provide level bottom. 2. Backfill with approved materials in a manner approved by the Engineer. (c) Excavating and Backfilling for Absorption Fields are specified in Item 400, Excavation and Backfill for Structures : 1. Excavate trenches a minimum 12 in. in width and 14 in. in depth, minimum, for a single pipe. 2. Backfill absorption trenches immediately with approved backfill materials to the elevations and grades as shown on the plans, or as directed by the Engineer. (4) Identification. (a) Arrange for installation of green warning tape directly over piping (including absorption field piping), at outside edges of underground structures, and at outside edges of absorption fields. (b) Use detectable warning tape over piping, over edges of underground structures, and over edges of absorption fields. (5) Septic Tank Installation. (a) Install precast concrete septic tanks level according to ASTM C 891. (6) Piping Applications. (a) Use pipes, fittings, and joining methods, for all piping sizes, according to the following applications: 1. Install solid piping and fittings to connect septic tank with leaching pipes. 2. Install leaching piping and fittings. Install leaching pipe with perforations at bottom. (7) Pipe Joint Construction and Piping Installation. (a) Join and install solvent-cement-type PVC pipe and fittings according to ASTM D 2855 and ASTM F 402. (b) Join gasketed PVC pipe and fittings with elastomeric seals according to ASTM D 3212. 5-7 3504
(c) Install distribution PVC piping according to ASTM D 2321. (d) Install leaching PVC piping according to ASTM D 2321 and ASTM F 481. (8) Absorption Field Installation. (a) Filtering Material. Place a supporting layer of filtering material over the compacted trench base to a compacted depth not less than 12 in. below bottom of pipe, or as shown on the plans. (b) Install distribution piping at a minimum slope of 1% and a maximum slope as determined by the Engineer. (c) Install leaching piping solidly bedded in filtering material, with full bearing for each pipe section throughout its length. Maintain pipe alignment with no slope, or as directed by the Engineer. 1. Install perforated pipe with perforations down and joints tightly closed. Install collars and couplings as required. 2. Install elbow fittings with tight joints. 3. Place additional filtering material as needed and as directed by the Engineer. (d) Install filter mat over filter material before backfilling. (e) Place layers of sandy loom topsoil above area. Provide grass seed or hydromulch with perennial grasser or a mixed variety or as shown on the plans. Provide side slope and tie slope toe smoothly into existing grade as shown on the plans or as directed by the Engineer. (f) Install distribution piping at a minimum slope of 1% and a maximum slope as directed by the Engineer. (9) Cleanout Installation. (a) Install cleanouts and extension from piping to cleanout at grade as indicated. Use 4 in. PVC pipe with threaded PVC cap. Set top of cleanout 2 in. above surrounding grade. (b) Install cleanouts and extension from piping to cleanout at grade as indicated. Set cleanout housing and cover in concrete block 18 by 18 by 12 in. deep, unless location is in concrete pavement. Set top of cleanout 1 in. above surrounding grade or flush with grade if installed in pavement. (c) Refer to Special Specification, Toll Plaza Facility Division 3 Section Cast-in- Place Concrete for formwork, reinforcement, and concrete. (10) Connections. (a) Connect sanitary sewerage piping to septic tank. (b) Connect piping between septic tank system structures and absorption fields. (11) Field Quality Control. 6-7 3504
(a) System Tests. Perform testing of completed septic tank system piping and structures according to authorities having jurisdiction. (b) Additional Tests. Fill underground structures with water and let stand overnight. If water level recedes, locate and repair leaks and retest. Repeat tests and repairs until there is no leakage. (c) Williamson County and Cities Health District Inspections. The Contractor shall coordinate with Williamson County and Cities Health District for the required construction inspections and final acceptance inspection. (12) Cleaning. (a) Clear interior of piping and structures of dirt and other superfluous material as work progresses. (b) Maintain swab or drag in piping, and pull past each joint as it is completed. Place plugs in ends of uncompleted pipe at end of workday or when work stops. 5. Measurement. This Item will be measured by the each, installed, complete in place, made fully operational and tested in accordance with this special specification or as directed by the Engineer. 6. Payment. The work performed and the materials furnished in accordance with this Item and measured as provided under Measurement will be paid for at the unit price bid for Septic Tank System. This price shall be full compensation for furnishing, placing and testing all materials and equipment, seeding, and for all tools, labor, shop drawings, documentation, and incidentals necessary to complete the work. 7-7 3504