SSTS design and installation best practices

The following list of best practices for SSTS installations was drafted by St. Louis County, Minn., in 2008 based on the experiences of SSTS installers and inspectors.

ssts-piping

Outside the tank, the pressure pipe can sag in the area between the tank and the undisturbed soil as the ground settles. This dip is where ice can build up and plug the system. Make sure backfill around the tank is tapped down well, especially beneath the pressure pipe outlet. Second, install a short length of sturdy (schedule 40) 4-inch pipe from the tank to the undisturbed soil. The 4-inch pipe is less prone to sagging. Connect the 4-inch pipe to the regular 2-inch pressure pipe with a reducer adapter.

 

  • Inside the tank, use a quick release hard coupling for pump line rather than a flexible coupling. Coupling should be no more than 2 feet below grade, or use a system that allows for easy pump removal without entry.
  • Do not bury manhole covers.  
  • Install an alarm on the effluent filter. Plugged filter screens can allow septic tank liquid levels to increase and bypass greases over the top into the pump tank and then into field.
  • If manifold is 2-inch and laterals are 1.5-inch, drill an extra orifice in the bottom of the manifold to allow it to drain.
  • If tank is in a wet location, keep the tank shallow and wrap seams and riser column with water proofing membrane. Utilize factory foamed tanks. Install drain tile around tank to lower infiltration potential if grade allows.
  • Utilize factory foamed tanks and lids.  
  • Insulate pressure manifolds.
  • Pay attention to storm water management in both design, construction and final landscaping of the area.
  • Carefully bed tanks with sand or pea rock and backfill with material devoid of large rocks.
  • Properly recycle mercury floats, control boxes, and other hazardous components.
  • Double check final cover amounts to insure it has not been lost in shaping of system.
  • Verify soils early.
  • Plan access routes of materials carefully. Follow them and do not compromise downhill and under bed dispersal capability.
  • Carefully monitor materials as they arrive from the pit; they can change.  
  • Do not use dirty rock — ever.
  • Sleeve pump line with 4-inch PVC to undisturbed ground; seal with a flexible connector or 4/2 bushing
  • Install and anchor inspection pipes in rock bed.

 

A good way to insulate tanks is to use spray foam insulation because it eliminates gaps. It should cover the upper half of the tank. Spray foam can also be used to insulate the underside of riser lids. The foam insulation is applied by the tank manufacturer at their plant.

A good way to insulate tanks is to use spray foam insulation because it eliminates gaps. It should cover the upper portion of the tank. Spray foam can also be used to insulate the underside of riser lids. The foam insulation is applied by the tank manufacturer at their plant.

 

  • Cut kerfs (slits) in inspection and access pipe tops to allow easier cap removal.
  • Use drain back on supply lines instead of deep burial pump lines. If this is not possible, insulate over supply line at all locations where it is holding water less than 7 feet underground and 4 feet in all directions where it is close to surface.  
  • Give your inspector adequate notice about finals. Notify them at their office regarding your plans and anticipated schedule for constructing a system. Good communication is essential to prevent conflicts and delays.
  • Draw up an as-built for systems and give to both the homeowner and inspector.
  • Do not undersize pumps, use 2-5 feet of distal head in design.
  • Read the entire design before system is constructed and call designer about suggested design changes and correction of mistakes. Adjustments are sometimes needed. Designer should check with inspector about necessary documentation.
  • Verify design system location before building it. Designer should stake out location.
  • Double check property lines and how these line locations were arrived upon.  
  • Look around for missed wells prior to construction.
  • Heavily straw systems constructed in late season.
  • Put on placard or notice on cap or lid of effluent screen riser to identify location.
  • Seal between plastic risers with silicone caulk and or wrap with waterproofing membrane.
  • Encourage property owner to maintain an O & M service contract on the systems built or repaired.
  • Encourage septic tank size upgrades for big families if needed.
  • Recommend lint filters for everyone; insist for large families.
  • Recommend freezing protection measures for low winter water use applications.
  • Explain the onsite system and how it works to the property owner before you leave the site.
  • Build the best system you can.
  • Stand by your work.

 

Systems installed during the fall should be insulated with a layer of mulch or straw over the mound/treatment field to help prevent problems with freezing that can occur before a grass or other vegetative cover can be established

Systems installed during the fall should be insulated with a layer of mulch or straw over the mound/treatment field to help prevent problems with freezing that can occur before a grass or other vegetative cover can be established.