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Typical data on the expected effluent wastewater characteristics from a residential septic tank with and without an effluent filter vault. Available data from the US EPA is also presented. Data from the Crites/Tchobanoglous book has been presented since this data may coincide with a future wastewater treatment system for the facility that may be considered relatively conventional, particularly with respect to effluent filter data. The next sampling protocol consisted of sampling soil from under the middle leachline of the three leachlines located in the north disposal area. Excavation was conducted using a Case Extend-a-hoe backhoe near the midway point of the middle leachline, with sampling from the referenced depths. Soil samples were also retrieved using the Extend-a-hoe from virgin, or unused soil at the north property line, outside of the leachfield area to compare with the soil chemistry test results from under the leachline. Typically, an extend-a-hoe can excavate down to 18 ft. However, the subsurface soils at the 14 ft depth were extremely tight and compact at both excavation sites. Just as if a drill rig encounters "auger refusal" and cannot drill any deeper, the extend-a-hoe could not excavate any deeper. Therefore, the deepest samples were retrieved from this 14 ft depth. RESULTS AND DISCUSSION The influent and effluent analyses of the Nottingham Onsite Wastewater Treatment System are found below in Table 1. Testing revealed expected and unexpected results. Expected results were those constituents that decreased in concentration after treatment, such as TDS, TSS, BOD, COD, TOC, and oil and grease. Constituents whose concentrations were unexpected, were a decrease in dissolved oxygen (DO) concentrations in the effluent, which should have increased after the introduction of oxygen through the air diffusers. The increase in nitrification potential, also from the introduction of oxygen, would have increased the potential for the formation of nitrate in the effluent, but no nitrate was detected (ND). Overall, the concentrations of the constituents generally correlate with the book values presented from the two reliable sources, but may imply that the Nottingham unit does not perform as it once did, particularly with regard to DO. Page -2- Chesney Consulting