The Northampton Conservation Commission on June 26 issued a negative determination (checking Box 2 on the RDA form) for a remedial tight-tank septic installation at a warehouse on East Hampton Road, concluding the proposed work will not alter wetland resource areas regulated under the local wetlands ordinance.

Colm Desto of Arlo Vex, representing Phillips Enterprises, explained the owners failed a Title 5 percolation test because test pits encountered fill and no native soil suitable for a septic leach field. Desto said the Board of Health had approved the tight-tank approach and that the proposed tight tank would sit “right where the existing septic tank is,” with removal of the existing leach field. The plan retains the existing line from a second building and locates all work outside flagged wetland areas, though entirely within the riverfront (100-foot) area.

Commissioners asked technical questions about operation, maintenance and contingency measures. Desto said the owner will have a contract with a licensed septic hauler for regular pump-outs; the tight tank includes multiple float alarms and backup power and was designed with conservatism in tank sizing. He said the proposed tight tank is sized at about 3,000 gallons and that the existing septic tank is likely around 1,500 gallons. The applicant described buoyancy (ballast) wings and a buoyancy calculation to prevent the tank from rising in saturated soils.

Commissioners also discussed erosion-control measures for removal of the leach field and proposed silt-fence placement around the limit of work; the applicant said erosion controls will be installed outside the wetland buffer. Commissioners asked whether sewer connections exist nearby; staff and participants said municipal sewer is roughly 1,800 feet away on Earl Street and that a sewer connection would be a substantial expense.

After discussion, a motion was made, seconded and approved by roll call to issue a negative determination (Box 2) that the work will not alter the wetland resource areas. The commission recorded an affirmative roll call (Paul, David, Beth, Melissa, Mason, Downey and Kevin voted yes).