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CONFIDENTIAL ATTORNEY-CLIENT PRIVILEGE Mr. Scott Ivlalm Cassel Malm Fagundes, UP Septern bet- 9, 2_008 Page 4 The design of the wastewatcr treatment system did not take the BOD strength into account. A design that included anaerobic treatment unit could have provided eftlucnr with much lower BOD, potentially avoiding the high regulatory costs and disposal system performance issues. Chesney's report did not specify details for the installation of piping above the biombe filter,which may have contributed to the incorrect installation. The primary disposal field was constructed in wet weather as is evident in the photographs. The surface was subject to compaction and wet surface seal formation. The Infiltrator manufacturer specifically wams against construction in these conditions. The contractor should be faniil_iar with this problem from previous experience with leach fields and with experience regarding general compaction of soils. At a minimum, the surfaces should have been scraped and scarified prior to placing and covering the infiltrators. Based on cumulative flow measurements until surfacing of effluent,Mr. Schenonc estimated that the storage volume in the Infiltrator chambers was only 1,400 gallons versus the 5,000 gallon storage capacity given in the design report. During the testing performed by Brown and Caldwell on August 28, 2008, the cumulative volume pumped before initial surfacing was approximately 280 gallons with both pumps on, and 460 gallons with one pump on after allowing the first surfacing effluent to subside. As mentioned previously, the reduction in capacity from 5,000 gallons to 1,400 gallons or less likely occurred because the Infiltrator chambers were pressed into the muddy soil by the back hoe driving over the top of the installation prior to proper backfilling and compaction. Final cover should not have been compacted while subsoil conditions were wet. - The slope of the line to the secondary disposal area appears to have been inadequate based on the tendency of water to back up into the secondary distribution box. Alternative remedies for the primary disposal system design and construction errors are as follows: Disposal System Remedy Alternative 1: Excavate and reconstruct existing Infiltrator system. Disposal System Remedy Alternative 2: In the grass area north of die store, construct three new gravel-filled leach Gelds and seepage pits, each approximating the infiltrative areas of each of the two leach field/seepage pit combinations in the existing secondary system. Together with the existing secondary disposal system, this would provide a total of 550 feet of equivalent leach field under San Joaquin County standards. Abandon or greatly reduce the designated operational capacity of the existing primary disposal system.