NOTE This standard governs the materials, design criteria, fabrication, and installation of the site sanitary sewer collection system from the building service tie-in point to the point of connection at the public sewer main or on-site treatment facility. (1.1)

NOTE The system covered includes gravity sewer mains and service laterals, sanitary manholes, cleanouts, service wye and tee connections, pipe bedding and trench backfill, and sanitary lift stations with their wet wells, pumps, valve vaults, force mains, and controls. (1.2)

NOTE Where the public sewer extension within the right-of-way is governed by the authority having jurisdiction (AHJ) standard details, those details govern that segment and this standard governs the on-site portion only. (1.3)

NOTE The following are outside the scope of this standard. (1.4)

NOTE Site sanitary work is intrinsically a coordination problem before it is a piping problem. (1.5)

NOTE The invert elevation at the public sewer tap fixes the entire downstream geometry of the on-site system: every upstream invert, manhole rim, and minimum-cover constraint flows backward from that one elevation. The need for a lift station, the achievable pipe slopes, and the conflict clearances with water main and storm are all decided early, in concert with Site Utilities, Storm Drainage, and Earthwork. Treat the tap invert and the design peak flow as the two anchor values that must be confirmed before pipe materials or structures are selected. (1.6)

NOTE Materials, design, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited or the authority having jurisdiction adopts a different edition. (2.1)

NOTE Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing. (2.2)

NOTE ASTM F679 has been withdrawn; its scope for large-diameter PVC gravity sewer pipe was consolidated into ASTM D3034, which now covers 3 in. through 60 in. (2.3)

NOTE Any reference, submittal, or product data citing F679 for sewer pipe shall be updated to D3034. Citing the withdrawn standard creates submittal-review confusion and a potential non-compliance finding by the reviewing utility. (2.4)

NOTE The Ten States Standards are a state-adopted design-criteria floor, not an ASTM or ASCE numbered product standard. (2.5)

NOTE The Recommended Standards for Wastewater Facilities are adopted by regulation or policy in most of the continental United States and establish the effective minimum criteria for gravity sewer slope, manhole spacing, and lift station design. Where the local AHJ has adopted a more stringent criterion, the AHJ criterion governs. (2.6)

NOTE The Contractor shall submit the following action submittals for review and approval before any sanitary sewer material is ordered or installed: (3.1.1)

NOTE The Contractor shall submit the following closeout submittals before final acceptance of the sanitary sewer system: (3.2.1)

NOTE The Contractor shall employ installers experienced in the placement, jointing, and testing of buried gravity and pressure sewer pipe of the materials and sizes specified. (4.1)

NOTE I/I prevention is the quality measure that matters most over the life of the system. (4.2)

NOTE Inflow and infiltration (I/I) is groundwater and stormwater entering the sewer through defective joints, cracked structures, and unsealed pipe penetrations. Excess I/I consumes hydraulic capacity, drives up treatment cost, and is the most common reason a utility rejects or conditionally accepts a new collection system. The single highest-leverage I/I defense is a properly installed flexible boot connector at every pipe-to-manhole penetration; mortared penetrations crack with settlement and are the dominant infiltration path. The testing requirements in this standard exist primarily to verify I/I integrity before backfill makes remediation destructive. (4.3)

NOTE The gravity sewer pipe material shall be selected for the burial depth, soil and groundwater conditions, and utility-conflict clearances of the run. (5.1.1)

NOTE PVC gasketed sewer pipe is the default gravity material for the great majority of site sanitary runs at normal depth. HDPE is selected where fusion-welded leak-free joints, long deflected pulls, or directional drilling are advantageous. Ductile iron is reserved for shallow-cover crossings, restrained-joint conditions, and the rigid segment at the building connection where loading or proximity to other utilities requires it. (5.1.2)

NOTE The gravity sewer shall be designed to maintain a self-cleansing velocity of at least 2.0 ft/s when flowing full or half-full at the design peak flow. (5.2.1)

NOTE Self-cleansing velocity keeps solids in suspension so the pipe scours itself rather than accumulating a sediment bed that reduces capacity and generates odor. The minimum slope that achieves 2.0 ft/s depends on pipe diameter and the Manning roughness coefficient; smaller pipe needs a steeper slope. A single flat minimum slope applied across all diameters is wrong in both directions: it is non-conservative for 8 in. pipe and grossly over-steep for 6 in. laterals. Compute the minimum slope per diameter. (5.2.2)

NOTE Each building service lateral shall connect to the main through a factory-molded wye or tee fitting, or an approved manufactured saddle wye where a field connection to an existing main is required. (5.3.1)

NOTE Field-cored connections made without a proper manufactured saddle fitting are a leading source of I/I and of structural failure at the connection: a hand-cut hole with a mortared-in pipe stub cracks and admits groundwater. Specify a factory wye on new mains and an approved saddle wye fitting only where tying into an existing main. (5.3.2)

NOTE The pipe bedding and trench backfill class shall be selected to support the pipe, protect the joints, and transfer surface loads without overstressing the pipe wall. (6.1)

NOTE Bedding is the engineered material placed under and around the pipe up to the spring line or pipe crown; it controls pipe deflection and joint integrity far more than the native backfill above it. "Granular fill" with no gradation or AASHTO limit is an open invitation for the contractor to use angular crushed concrete or oversized stone that point-loads and cracks PVC bell joints. Specify the bedding class and the gradation limits explicitly. (6.2)

NOTE Manhole type and material shall be selected for groundwater, hydrogen sulfide exposure, and traffic loading. (7.1)

NOTE Precast reinforced concrete manholes per ASTM C478 are the dominant and default type. Fiberglass manholes per ASTM D3753 are selected where high groundwater, corrosive soil, or sustained hydrogen sulfide (H2S) exposure would attack concrete. H2S generation is most severe downstream of force main discharges and in low-velocity reaches; in those locations a corrosion-resistant manhole or a protective lining is warranted. Traffic loading determines the barrel diameter, base thickness, and frame-and-cover load rating. (7.2)

NOTE Joints between precast manhole sections shall be sealed with a rubber gasket conforming to ASTM C443 or a preformed flexible butyl sealant conforming to ASTM C990. (7.3.1)

NOTE Both jointing methods are accepted; the choice depends on the manufacturer's section design and the groundwater condition. The joint must remain watertight under external hydrostatic head, which is the I/I path most often overlooked because it is below grade and invisible after backfill. (7.3.2)

NOTE The manhole frame and cover shall be gray iron castings conforming to ASTM A48, Class 35B minimum, with a load rating selected for the location. (7.4.1)

NOTE A manhole in or near a trafficked area requires an AASHTO H-20 (HS-20) traffic-rated frame and cover; a non-traffic location in landscaping may use a lighter rating. Covers in flood-prone or high-I/I areas should be solid (no vent holes) and may be gasketed or locking. Specify the rating, lid type, and any locking or insert requirement so the contractor orders the correct casting. (7.4.2)

NOTE A lift (pump) station shall be provided only where gravity flow to the public main or on-site treatment is not feasible at the design depth and slope. (8.1)

NOTE A lift station introduces ongoing energy cost, mechanical maintenance, and a wet-weather failure mode that gravity sewers do not have, so it is an option of last resort. Confirm during early design whether the site can reach the public main by gravity at acceptable cover and slope; if it cannot, the lift station must be sized and located before the collection-system layout is finalized, because the station footprint, electrical service, and force main routing constrain the whole site. The decision threshold is governed by the tap invert elevation, site grades, and the resulting required excavation depth. (8.2)

NOTE Lift station pumps shall be submersible non-clog centrifugal solids-handling pumps, applied and selected per ANSI/HI 1.1-1.6, in a duplex (minimum two-pump) arrangement for redundancy. (8.3.1)

NOTE A single-pump station has no redundancy: a pump failure backs up the entire tributary system. The duplex arrangement allows either pump to meet the design flow alone with the second pump as standby, alternating to equalize wear. Non-clog impellers and a minimum solids-passing sphere are required because raw sewage carries rags and solids that bind narrow passages. (8.3.2)

NOTE The wet well material and effective volume shall be selected to limit pump cycling and to provide emergency storage. (8.4.1)

NOTE Wet well storage volume sets the pump cycle time. Too small a volume causes the pump to start and stop rapidly; frequent starts overheat the motor, accelerate wear, and void the pump warranty. The active volume between the pump-on and pump-off levels must be large enough to hold cycle time within the motor manufacturer's maximum starts-per-hour limit at the design flow. The wet well must also provide reserve storage above the high-level alarm to ride through a short power or pump outage without an overflow. (8.4.2)

NOTE The hazardous-area classification of the wet well and valve vault shall be determined per NFPA 820, and the electrical design shall match that classification. (8.5.1)

NOTE NFPA 820 classifies the wet well interior and connected spaces as hazardous (typically Class I, Division 1 inside the wet well and Division 2 in the connected valve vault) because of the potential for explosive sewer gas. That classification drives the motor and cable ratings, the conduit sealing fittings, and the ventilation design. Omitting the classification from the documents is a frequent cause of electrical-subcontractor RFIs and rework, because the installer cannot select compliant equipment without it. (8.5.2)

NOTE A valve vault separate from the wet well shall house the discharge check valves, isolation valves, and force main connection. (8.6.1)

NOTE Keeping valves out of the wet well keeps maintenance staff out of the hazardous, gas-laden wet well for routine valve work and keeps the valves above the sewage. Each pump discharge needs a check valve to prevent backflow when it stops and an isolation valve to allow servicing one pump while the other runs. (8.6.2)

NOTE Odor control shall be evaluated for any lift station or force main discharge in proximity to occupied buildings, building entries, or parking areas. (8.7.1)

NOTE Hydrogen sulfide released at the wet well vent or at the force main discharge manhole produces odor complaints and corrosion. A station that vents next to a building entry or a parking area is a post-occupancy liability. Passive venting (a carbon-media canister or a tall vent stack) suffices for low-strength or remote stations; an active carbon or chemical scrubber may be warranted where the station is close to occupied space or the wastewater is septic. (8.7.2)

NOTE All gravity sewer testing shall be completed and accepted before final backfill compaction and surface restoration over the tested segment. (9.1)

NOTE Test sequencing is a requirement, not a convenience. A low-pressure air test or deflection test run after the trench is fully backfilled and paved makes any failure expensive to find and destructive to repair. The acceptance tests must be scheduled into the construction sequence so they occur on the open or lightly-backfilled trench, with the spec stating the order explicitly so the test is not skipped. (9.2)

NOTE Pipe shall be installed to line and grade on a continuously supported, properly bedded trench bottom, with bell ends laid facing upstream. (10.1)

NOTE Sewer pipe is laid uphill against the flow with the bell facing upstream so the spigot of each joint points downstream into the bell, which keeps the joint from being pried open by flow and bedding movement. Line and grade are non-negotiable on a gravity sewer; small grade errors that create bellies (low spots) trap solids and defeat the self-cleansing design. (10.2)

NOTE Plastic pipe shall be protected from prolonged ultraviolet exposure and supported to prevent deformation during storage. (11.1)

NOTE PVC and HDPE pipe degrade and lose impact strength under sustained sunlight, and they take a permanent set if stored unsupported in tall stacks or over point supports. Gaskets and elastomeric connectors must be kept clean and out of the sun. Castings, pumps, and control panels must be kept dry and undamaged until installation. (11.2)

NOTE The Contractor shall warrant the installed sanitary sewer system against defects in materials and workmanship for the project warranty period. (12.1)

NOTE The Contractor shall furnish the spare parts and special tools needed to keep the lift station in service after acceptance. (13.1)