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2 O <br /> N SYSTEMS INC <br /> Environmental Onsite Wastewater Solutions6" <br /> M E M Q R A N D U M <br /> DATE: November 2, 2006 <br /> TO: Regulators, Distributors, Contractors and Designers <br /> FROM: Infiltrator Systems lnc. <br /> RE: Infiltrator Chamber installations in very fine, uniform sands <br /> Infiltrator Systems Inc. (ISI) has installed over 42 million chambers (1.5 million systems) since first <br /> being introduced in 1986. In the vast majority of chamber installations in sand and other soil <br /> types nationwide, ISI does not recommend installing filter fabric. <br /> There are some approved septic sites where very fine, uniform sand exists. While these sites are <br /> rare and isolated there have been instances where this fine sand has migrated through the <br /> sidewall of the chamber.The migration is due to this type of sand's inability to "bridge", and <br /> poor site drainage control or other circumstances outside the control of ISI.As an additional <br /> measure of protection 1S1 suggests (non-mandatory) the installation of filter fabric over the <br /> chambers when confronted with the specific conditions as follows: <br /> 1. Chambers installed in uncompacted, very fine, uniform sands. <br /> 2. Installations left uncovered and subject to a major rain event. <br /> 3. Systems not sodded (or stabilized) in a timely matter after final cover-up has occurred. <br /> 4. A drainfield located in a poorly drained area such as: an area subject to inundation by <br /> frequent flooding events, surface drainage of rainwater directed over the system, or a <br /> drainfield not protected by gutters, curtain drains, or installed in a high water table area. <br /> The use of filter fabric when confronted with the specified conditions as outlined above will not <br /> void the product warranty. Please see attached Technical Bulletin for additional information. If <br /> you hove any questions please contact the Technical Services Department at 1-800-221-4436. <br /> Page 1 of 2 <br />