Use of Recirculating Sand Filters

(1) A recirculating sand filter ("RSF") or equivalent alternative technology approved by the Department in accordance with 310 CMR 15.280 through 15.288 is a required component of all systems designed to serve a facility or facilities with a design flow of 2,000 gpd or more to be located in a Nitrogen Sensitive Area, as designated in 310 CMR 15.214(1)(a), provided that such RSF shall not be required for a facility for which subdivision approval has been obtained to construct dwellings with a cumulative total design flow of 2,000 gpd or greater if a disposal system construction permit to construct a system with a total design flow of less than 2,000 gpd in full compliance with 310 CMR 15.000 on each of the subdivision lots to be served by a system is obtained and such separate subdivision lots are to be conveyed to independent owners. (2) A recirculating sand filter or equivalent alternative technology approved by the Department in accordance with 310 CMR 15.280 through 15.288, may be used to enhance nitrogen removal in systems in Nitrogen Sensitive Areas designated pursuant to 310 CMR 15.214(1)(a), in accordance with 310 CMR 15.217 (Systems with Enhanced Nitrogen Removal). (3) Recirculating sand filters designed and approved in accordance with Department guidance are certified for general use. (4) Recirculating sand filters or equivalent alternative technology shall meet the following requirements: (a) effluent discharge concentrations shall meet or exceed secondary treatment standards of 30 mg/L BOD5 and 30 mg/L TSS. The effluent pH range shall be 6.0 to 9.0. (b) total nitrogen concentration in the effluent shall not exceed 25 mg/L. (c) system owners shall have effluent quality monitored quarterly for systems serving a facility with a design flow of less than 2,000 gallons per day, and both influent and effluent quality monitored quarterly for systems serving a facility with a design flow of 2,000 gallons per day or greater, for BOD5, TSS, pH and total nitrogen, unless otherwise required or approved by the Department. Unless otherwise required by the Department, the system owner shall submit all monitoring results to the local Approving Authority and the Department by January 31st of each year for monitoring conducted during the previous calendar year. (d) recirculating sand filter systems shall contain all components of a standard on-site system and be capable of functioning as a conventional system. Any departures from this provision require written approval from the Department. (e) the system owner shall notify the local Approving Authority of any system failure within 24 hours of detection of such failure. (f) pressure distribution, in accordance with 310 CMR 15.254, is required for all systems serving a facility with a design flow of 2,000 gallons per day or greater. Pressure distribution systems shall be designed in accordance with Department guidance. (g) for systems serving a facility with a design flow of 2,000 gpd or greater, the separation from high groundwater as required under 310 CMR 15.212 shall be calculated after adding the effect of groundwater mounding to the high groundwater elevation as determined pursuant to 310 CMR 15.103(3). (h) by January 31st of each year, unless otherwise determined by the Department, the system must be inspected at least annually by a Massachusetts certified operator of an appropriate grade to operate the system, unless the Department has approved in writing a reduction in frequency of inspection or the facility is subject to a Department approved comprehensive local plan of on-site system inspection, the system owner shall submit a certification by the system operator to the local Approving Authority and the Department for the previous calendar year stating that the system and its components are functioning as designed and were inspected in accordance with the Department’s approval. (i) an operation and maintenance manual shall be prepared by the system designer or a Massachusetts Registered Professional Engineer and submitted as part of the application.