310 C.M.R. 15.221 – General Construction Requirements for All System Components

(1) All tanks, including septic tanks, distribution boxes, pump chambers, dosing chambers and grease traps, shall be either:
1. (a) watertight through manufacturer's specification and warranty; or
2. (b) made watertight by the manufacturer, equipment supplier or installer using asphalt or synthetic polymer sealer specified by the concrete or synthetic material manufacturer.
(2) Septic tanks, grease traps, pump chambers, dosing chambers and distribution boxes shall be constructed or set level and true to grade on a level stable base which has been mechanically compacted. If the component is placed in fill, proper compaction is required to ensure stability and to prevent settling; native ground with a six inch aggregate base is otherwise adequate.
(3) Septic tanks, grease traps, pump chambers and dosing chambers shall be equipped with a watertight access manhole(s) with a minimum diameter of 20 inches and constructed of durable material.
(4) All system components shall be constructed of corrosion resistant materials.
(5) All piping shall be a minimum of SDR 35 PVC in areas not subject to automobile or heavy equipment traffic. In areas where such traffic exists or is anticipated, Schedule 40 PVC, or an equivalent standard approved by the Department, shall be used.
(6) All pressurized pipes shall be designed and installed to meet the following requirements:
1. (a) to prevent freezing by being installed below the frost line, by being adequately insulated if installed above the frost line, or be self-draining;
2. (b) to specify the appropriate class or schedule of pipe to withstand maximum pressure and/or anticipated vehicular loads; and
3. (c) to specify appropriate thrust blocking at all angles, bends, branches, plugs and wherever else necessary to prevent disruption of proper functioning of the line.
(7) The top of all system components, including the septic tank, distribution box, pump chamber, dosing chamber and soil absorption system, shall be installed no more than 36" below finish grade.
(8) Where any portion of any component is to be placed at or below the ground-water table, all system tankage, including the septic tank, distribution box, pump chamber or grease trap, shall be designed with counter weights, anchors or ballast and a buoyancy calculation for the entire volume of each component, when empty, shall be performed and submitted with the system plans and specifications.
(9) Recirculating sand filters or equivalent technology shall be used in accordance with the provisions of 310 CMR 15.202 and Department guidance.
(10) Except as provided in 310 CMR 15.232(3), all pipes connecting system components shall be designed to provide a minimum flow velocity of two feet per second when flowing full.
(11) All septic tanks, tight tanks, pump chambers, dosing chambers and grease traps shall be watertight.
(12) All system components shall be marked with magnetic marking tape or a comparable means in order to locate them once buried.
(13) For septic tanks and d-boxes equipped with risers, the risers shall be no deeper than six inches below ground surface.