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One way to avoid sampling this water is to wait for it to flow past the well. The ground water gradient in the area of the Jordan site is approximately 0.0021. The porosity of silty-sand is 0.2, the permeability is approximately 1 x 10-1 ft/day. Using Darcy's equation, ground water flows beneath the Jordan site at the rate of 0.001 ft/day. One would have to wait years before the pressure wave affected water has moved past the well. A second way to deal with this problem is to remove the affected water. Assume that the water within a 1 foot radius of the well must be removed, the well screen is 20 feet long, and the soil porosity is 0.2. The volume of water that would have to beumped from the well would be approximately 94 gallons (30 well volumes Therefore, purging the well oat least 94 gallons before sampling is sufficient to remove the water affected by development. This latter option is the one that will be employed by Kleinfelder when we collect samples 24 to 48 hours after development. 4. Location of Sewer Lines - The attached map shows the location of the main sewer line and lateral with respect to the proposed monitoring well locations. Please review this letter at your earliest convenience. If you have any questions, give me a call. Sincerely, KLEINFELDER SAH JOAQUIN LOCAL HEALTH DISTRICT Z. Hazel ton Ave.-Phone : 466--6781 le ti.Y,t�r P._ . B.:x 2_9 Stockton, Ca. 96201 TimothyA Crandall 0 nved Staff Engineer Environmental Services Division '-"'r°)`d with see Remarks Central Valley Group L DisapTroved ; See Remarks TAC:rmm 124-88-1234 Date "'lSy Approval of J.ese plans extends only to that w;Fich is sho%v_i and described here- on but does not authorize or approve any omission or deviation of require- ,ients of state laws or local Ordinancaa. �1.�-�i �'h��,FB�Ksn� ►Rnith--�.s tS i S 1'>lt�r AIA_