BIL 269 Draft 01 2008-2010 - Laserfiche WebLink

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(20) Amending Section 1611.0. Section 1611.0 is amended to read: "1611.0 Irrigation /Disposal Field Construction. (See Figure 16 -5.) The authority having jurisdiction may permit subsurface drip irrigation, mini - leach field or other equivalent irrigation methods which discharge gray water in a manner which ensures that the gray water does not surface. Design Standards for subsurface drip irrigation systems and mini -leach field irrigation systems are as follows: (A) Standards for a subsurface drip irrigation system: (1) Minimum 140 mesh (115 micron) filter with a capacity of 25 gallons per minute, or equivalent, filtration, sized appropriately to maintain the filtration rate, shall be used. The filter back -wash and flush discharge shall be caught, contained and disposed of to the sewer system, septic tank, or with approval of the authority having jurisdiction, a separate mini -leach field sized to accept all the back wash and flush discharge water. Filter backwash water and flush water shall not be used for any purpose. Sanitary procedures shall be followed when handling filter back -wash and flush discharge of gray water. (2) Emitters shall have a minimum flow path of 1200 microns and shall have a coefficient of manufacturing variation (Cv) of no more than seven percent. Irrigation system design shall be such that the emitter flow variation shall not exceed plus or minus ten percent. Emitters shall be recommended by the manufacture for subsurface use and gray water use, and shall have demonstrated resistance to root intrusion. (3) Each irrigation zone shall be designed to include no less than the number of emitters specified in Table 16 -3, or through a procedure designated by the authority having jurisdiction. Minimum spacing between emitters is 14 inches in any direction. (4) The system design shall provide user controls, such as valves, switches, timers, and other controllers as appropriate, to rotate the distribution of gray water between irrigation zones. (5) All drip irrigation supply lines shall be polyethylene tubing or PVC class 200 pipe or better and schedule 40 fittings. All joints shall be properly solvent- cemented, inspected and pressure tested at 40 psi, and shown to be drip tight for five minutes, before burial. All supply lines will be buried at least eight inches deep. Drip feeder lines can be poly or flexible PVC tubing and shall be covered to a minimum depth of nine inches. 8