2018 Indiana Design and Installation Manual 6 www.eljen.com
1.0 Conditions for Use
1.0.1 ALTERATION OF MODULES: GSF modules shall not be altered by cutting or any other type of physical
modification.
1.0.2 WATER SOFTENER BACKWASH: Water softener backwash shall be discharged to a separate soil
absorption field meeting all required state codes and local regulations.
1.0.3 SEPTIC TANK OUTLET FILTERS: Eljen requires the use of outlet filters on all tanks including single
compartment tanks, up-sized tanks or when the dwelling has a garbage disposal installed.
1.0.4 GARBAGE DISPOSALS: Eljen discourages the use of garbage disposals with septic systems. If a GSF
system is to be designed and installed with garbage disposals the following measures must be taken to prevent
solids from leaving the tank and entering the GSF system:
Increase the septic tank capacity by a minimum of 30% or
Installation of a second septic tank installed in series if a multi-compartment tank isn’t used
1.0.5 ADDITIONAL FACTORS AFFECTING RESIDENTIAL SYSTEM SIZE: Homes with expected higher than
normal water usage may consider increasing the septic tank volume as well as incorporating a multiple compartment
septic tank. Consideration for disposal area may be up-sized for expected higher than normal water use.
For example:
Luxury homes, homes with a Jacuzzi style tubs, and other high use fixtures.
Homes with known higher than normal occupancy.
1.1 System Design
1.1.1 REQUIREMENTS: GSF systems must meet ISDH Rule 410 IAC 6-8.3 except as outlined in this manual.
The sizing tables in this manual applies to residential systems of any size and
Commercial systems with daily design flows less than or equal to 750 GPD
Sizing examples are found in this manual. Please contact Eljen’s Technical Resource Department at 1-800-444-
1359 for design information on commercial systems and adhere to ISDH Rule 410 6-10.1.
1.1.2 NUMBER OF GSF MODULES REQUIRED: The tables found in this manual indicate the minimum number
of A42 or B43 modules allowed. Systems can always be designed beyond the minimum required number of
modules. The minimum design requirements per 150 gpd are 6 A42 modules or 6 B43 modules.
1.1.3 SUITABLE SITE AND SOIL CONDITIONS: The Eljen Modules may be designed for all sites that meet the
criteria described in the Indiana State Department of Health, Residential Onsite Sewage Systems, Rule 410 IAC 6-
8.3 (70-73) or ISDH Rule 410 6-10.1 (78-80).
1.1.4 SEQUENTIAL LOADING: Sequential distribution may only be utilized for sloping sites. Sequential
Distribution uses a distribution box equipped with speed levelers. The uppermost line of the system and the inlet
to the distribution box will be left open. Down slope lines from the distribution box will have the speed leveler at 9
o’clock. Figure 2 demonstrates this practice which will fully utilize the uppermost section of the system prior to
spilling effluent into a lower row of modules. This is for use on any site with greater than 0.5% slope and parallel
distribution cannot be used. These systems are approved in writing on a case by case basis by the Eljen Technical
Department.
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