Septic system installation in Gray, Maine.

Maine has regulated septic systems since 1920, and the Maine CDC's Subsurface Wastewater Unit administers the state rules, including those governing site evaluators and local plumbing inspectors. In Gray, septic permits and inspections go through the Code Enforcement Office. The shoreland ordinance requires a plumbing permit, or a completed application with the site evaluation approved by the Plumbing Inspector, before a building permit is issued for anything that needs a new or expanded system.

Gray also asks for a soils report from a state-certified professional for uses that need subsurface disposal. That report covers seasonal high groundwater, ledge and drainage.

Soil maps for Gray show why every site evaluation differs. Hinckley and Windsor loamy sands drain very quickly. Lamoine and Scantic silt loams are wet glaciomarine soils. Paxton, Woodbridge and Ridgebury till have a dense layer about eighteen to twenty-two inches down. Lyman soils have bedrock at about that depth. Wet or shallow ground usually calls for a raised field built with imported fill, and the evaluator's design sets the elevation. Sand-dominated sites have the opposite concern: effluent moves quickly, so the separation to groundwater that the evaluator specifies is closely followed.

Once the system is backfilled, we grade the area and seed it so the field is covered in shallow-rooted grass.