Section 15.404 - Maximum Feasible Compliance - Approvals for Upgrades(1)Goal of Full Compliance. Wherever feasible, existing systems, including failed or nonconforming systems (other than systems threatening public health, safety, welfare or the environment as described in 310 CMR 15.304(2)) and existing systems required to be upgraded to Best Available Nitrogen Reducing Technology pursuant to 310 CMR 15.215(2)(a), shall be brought into full compliance through installation of one or more of the following:(a) an upgraded system which is in full compliance with 310 CMR 15.100 through 15.293;(b) an alternative system which has been approved for such use pursuant to 310 CMR 15.284 (remedial use), 15.285 (piloting), 15.286 (provisional approval), or 15.288 (certification for general use);(c) an RSF or equivalent alternative technology where the system is located in a Nitrogen Sensitive Area and has a design flow of 2000 gpd or greater in accordance with 310 CMR 15.202(1);(d) where proposed by the owner or operator, a shared system which has been approved for such use pursuant to 310 CMR 15.290 and 15.291; or(e) connection to a sewer system.(2) Where failure of the system is solely due to failure of the septic tank, distribution box, soil absorption system, piping, and/or building sewer, upgrade of that component(s) in full compliance with 310 CMR 15.000 shall be deemed to meet the goal of full compliance; provided that the upgraded component functions properly with the other system components, the system functions properly hydraulically, and the owner obtains a certificate of compliance from the Approving Authority for the component repaired or replaced. If other system failures are discovered during upgrade of that component(s), such other system failures shall be upgraded in accordance with 310 CMR 15.405.(3) When full compliance pursuant to 310 CMR 15.404(1) is not feasible, the Approving Authority may issue a local upgrade approval authorizing upgrade of the system with the goal of maximizing protection of public health, safety, welfare and the environment to the maximum extent feasible. The following requirements shall not be varied by the Approving Authority except as explicitly set forth in 310 CMR 15.404(3)(b) and (d): (a) a septic tank with an effective liquid capacity providing no less than 24 hours of retention time or 1000 gallons, whichever is greater, shall be provided unless the septic tank is an elevated tank constructed in accordance with 310 CMR 15.213 (construction in V-zones) in which case the effective liquid capacity may consist of a 500-gallon tank;(b) a minimum of four feet of separation between the bottom of the soil absorption system and the high groundwater elevation shall be provided, using fill if necessary. The Approving Authority may allow a three foot separation only in full compliance with 310 CMR 15.405(1)(h).(c) a minimum of four feet of naturally occurring pervious soil below the entire area of the soil absorption area and reserve area shall be provided;(d) the soil absorption system shall be designed to provide as much of the required area as possible on the facility served or, if proposed by the owner or operator, on an abutting facility pursuant to a valid recorded easement. The Approving Authority may reduce the required soil absorption system area no more than 25%, as provided in 310 CMR 15.405(1). Reductions in the required subsurface disposal area in excess of 25% may only be varied by the Department, and may require the installation of a Department-approved septic tank effluent tee filter, dosing of portions of the soil absorption system on an alternating basis, and/or other measures to protect the integrity of the soil absorption system; and(e) the soil absorption system shall not be located within 100 feet of a surface water supply or tributary to a surface water supply, within 50 feet of a private water supply well, or within the Zone I of a public water supply well.Amended by Mass Register Issue 1499, eff. 7/7/2023.Amended by Mass Register Issue 1501, eff. 7/7/2023.