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2.0 Design and Installation <br /> 2.8 DISTRIBUTION BOX CONNECTION: Plastic or concrete distribution boxes are acceptable. Provide <br /> D-Box(s) installed in accordance with 310 CMR 15.232. Distribution boxes must be installed level and on <br /> a compacted layer of sand or a base of gravel to prevent movement over time. Set gravity system <br /> distribution box outlet pipes 1/2" to 1/8" drop to per foot above the perforated pipe above the modules. A <br /> 2" minimum drop to the perforated pipe is required for pumped systems. Non-perforated pipes from the <br /> distribution box to the GSF modules must be placed on a compacted surface and secured with fill material <br /> that will prevent movement and settling. Dial-a-Flow fittings on outlet pipes are required for demand dosed <br /> systems. <br /> 2.9 PARALLEL DISTRIBUTION: Parallel distribution is the preferred method of dosing to a gravity or <br /> pump to gravity system. It encourages equal flows to each of the lines in the system. It is recommended <br /> for most trench systems. <br /> 2.10 SEQUENTIAL DISTRIBUTION: Sequential Distribution using a distribution box will fully utilize the <br /> uppermost section of the system prior to spilling effluent into a lower row of modules. This is for use on <br /> any site with greater than 0.5% slope when not using parallel distribution. <br /> FIGURE 4: SEQUENTIAL DISTRIBUTION DROP-BOX DETAIL <br /> B A <br /> GSF MODULES <br /> O (DDIAL-A-FLOW UPPER MOST TRENCH <br /> INVERT SETTING DIAL-A-FLOW FITTINGS ARE NOT <br /> INSTALLED ON THE OVER FLOW LINE <br /> B A FROM THE SEPTIC TANK <br /> OR THE DISTRIBUTION PIPE <br /> LEADING TO THE GSF MODULES <br /> GSF MODULES <br /> LOWERTRENCHES 0 <br /> THE INVER OF DIAL-A-FLOW'B" <br /> IS SET AT THE 9:00 POSITION <br /> GSF MODULES <br /> LOWEST TRENCH <br /> DIAL-A-FLOW FITTINGS ARE NOT INSTALLED <br /> 0 ON THE OVER FLOW LINE FROM A UPPER DROP-BOX <br /> OR THE DISTRIBUTION PIPE <br /> LEADING TO THE GSF MODULES <br /> THE INVER OF DIAL-A-FLOW'B" <br /> THE LOWEST TRENCH ALONG THE SLOPE IS SET AT THE 9:00 POSITION <br /> DOES NOT REQUIRE A DROP-BOX,ALTHOUGH <br /> RECOMMENDED WITH COMMERCIAL DESIGNS OUTFLOW TO <br /> FOR INSPECTION AND OBSERVATION DOWNSIDE <br /> IN FLOW FROM SEPTIC TANK, DROP BOX <br /> PUMP CHAMBER OR UP SLOPE <br /> DROP BOX <br /> OUTFLOW TO <br /> DOWNSIDE SLOPE <br /> DROP BOX <br /> OUTFLOW TO GSF <br /> IN FLOW FROM SEPTIC TANK, LATERAL LINE <br /> PUMP CHAMBE OR UP SLOPE OUTFLOW TO <br /> DROP BOX DOWNSIDE SLOPE <br /> DROP BOX <br /> OUTFLOW TO GSF <br /> LATERAL LINE <br /> 2022 California Design&Installation Manual Page 8 www.eljen.com <br />