Current through Register No. 50, December 12, 2024
Section Env-Wq 1109.07 - Filter Systems; Wastewater Disposal(a) Each component of a filter system shall comply with Env-Wq 1108.22(a)(1).(b) Each filter system shall include the following:(1) A strainer such as a pressure-type sand filter, a diatomaceous earth pressure or suction filter, or a cartridge-type filter;(2) A flow meter that also meets the requirements of (c), below;(3) A pressure gauge and an air relief valve for each filter;(4) A sight glass in each waste line from filter to backwash; and(5) A set of instructions for operating and maintaining the system.(c) Each flow meter installed on a PBF filter system shall be:(1) Capable of measuring flows that are at least 1.5 times the design flow rate;(2) Accurate within 10% of true flow;(3) Located where the operator or an inspector can read the meter in the normal course of operations or during a routine inspection, respectively; and(4) Installed in accordance with the manufacturer's specifications.(d) Pressure-type sand filters also shall comply with the following:(1) For low-rate rapid sand filters, the flow rate shall not exceed 3 gallons per minute per square foot of filter area;(2) For high-rate rapid sand filters, the flow rate shall not exceed 15 gallons per minute per square foot of filter area; and(3) Back wash flow rates shall be 10 to 15 gallons per minute per square foot of filter area.(e) Diatomaceous earth pressure or suction filters shall comply with the following: (1) The flow rate shall not exceed 2.0 gallons per minute per square foot of filter area; and(2) Filter piping shall provide for circulation through the filter only or be capable of selection to discharge to waste.(f) For cartridge-type filters, filter flow rates shall not exceed 0.375 gallons per minute per square foot of filter media.(g) Filter backwash and wastewater disposal shall be as follows: (1) Sewage and other wastewater, exclusive of filter backwash and pool drainage, shall be discharged into either a public sewer or a subsurface disposal system approved under RSA 485-A:29-44 and Env-Wq 1000;(2) Backwash and pool drainage shall be discharged: a. Into a public sewer through an air gap of not less than one inch; orb. Disposed of in a location or system approved by the department pursuant to RSA 485:3, X, RSA 485-A:29-44, RSA 485-A:13, I(a), or Env-Wq 402; and(3) When a pool or spa at a PBF is drained by discharge to a public sewer, the free disinfectant residual shall not exceed 3 mg/L chlorine or bromine.N.H. Admin. Code § Env-Wq 1109.07
Derived from Volume XLI Number 19, Filed May 13, 2021, Proposed by #13198, Effective 5/1/2021, Expires 5/1/2031 (see Revision Note #3 at chapter heading for Env-Wq 1100) (formerly Env-Wq 1106.07)