Plympton ZBA Hears Warnings That SLT Construction Lots Exceed Nitrogen Limits

PLYMPTON — May 21, 2026 — Plympton Zoning Board hears expert testimony that a proposed 40B development would drive well-water nitrates to more than double the federal drinking water limit. At a May 21 continuation hearing on SLT Construction's Chapter 40B comprehensive permit application, hydrogeologist Scott Horsley, retained by the Plympton Board of Health, presented a nitrogen-loading analysis calculating a downgradient concentration of 22 milligrams per liter for the 21-lot Spring Street project, against a federal standard of 10 milligrams per liter and a MassDEP planning threshold of 5 milligrams per liter. Peer reviewer Johnny Knowles of GEI Consultants confirmed the revised lot plan meets Title V requirements only if innovative and alternative septic systems are used, technologies currently prohibited by Plympton's Board of Health regulations. Horsley argued the prohibition is well-founded, citing data from the Massachusetts Septic System Test Center showing variable compliance rates with IA operation and maintenance contracts and the absence anywhere in the region of the "responsible management entity" that state and federal regulators now say is needed to make IA systems reliable. Fire Prevention Captain John Scherstein separately flagged unresolved access and water-supply concerns on the revised site plan. No votes were taken.