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The groundwater table is too shallow for seepage pits, and marginally sufficiently deep for sumps, since there must be a five-foot minimum distance between the bottom of the leachline trench or pit/sump and the depth to groundwater. Traditional sumps are typically 4 ft wide, 8 ft long and 10 ft deep. However, a shallow"sump" (16 ft x 2 ft x 4 ft) could be installed and maintain the five- foot minimum distance. Information obtained from the Environmental Health Department regarding the number of permits for repairs/additions also indicates the septic systems have a definite lifespan and consideration must be given to eventual replacement. If there will be leachfield area constraints, a filter bed may be considered since a shallow sump as described above would not be as protective of groundwater quality as a filter bed. This will be a determination made by the Environmental Health Department. TABLE 3 •cy.°si'6ri5�'°€4ed €c . [ PERCOI ATIONii `ES.'�.itES ETS z's-�9.-., s.i?.i�}. PARCEL No' r�TES ; 7)�FTH,'TEST DOLE DIAMETER rE(ff 1 E€: egAND P�RC:IiATE1N MIN B/IN .:, €''aa' sll7 ATE I'EI2G,TESTCONDUCTED1 ; :€' ,..,--'-. ?€ r.- ; .,' E`a., Y;. EPfd�p€(6P. §F...., ,��€S�e€`,,etai$§i€:fM i}4aa? '€ie?l .:` ' PARCEL I 40 Inches,4 Inches March 5,2004 8.8 MINAN PARCEL,2 38 Inches,4 Inches February 12,2004 1.0.7 MINAN PARCEL 3 39 Inches,4 Inches March 5,2004 13.6 MINAN LPARCEL 41 Inches,4 Inches March 5,2004 12.5 MINJN i 40 Inches,4 Inches February 12,2004 7.1 MIN/IN C. GROUNDWATER INFORMATION From backhoe test pits dug in the proposed effluent disposal area, the groundwater (zone of saturation, or phreatic zone) is located at approximately 12 ft below grade. Lines of Equal Depth maps published by the Flood Control District do not illustrate the groundwater depth or groundwater equal elevation for the north Tracy area. Since the groundwater elevation is comparatively high, there was no evidence of a perched water table condition or saturated soil conditions in the backhoe test pits or hand borings. Groundwater recharge is occurring from irrigation water percolation and water from the Tom Paine Slough. Directional flow is probably variable depending on external conditions, such as tidal action. The Environmental Health Department has stipulated the existing wells located at the dairy barn be tested for the agrichemical Dibromochloropropane (DBCP) and nitrate. The new well is denoted as the "New Well" on the Analysis Report, which was drilled in 1989 to a depth of 280 feet. The second well is denoted as the "Old Well" which was drilled in 1945 to a depth of approximately 100 feet. 6 Chesney Consulting