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Page 1 of 4 r `q/ Frank Girardi [EH] From: Micheline Kipf[mkipf@condorearth.com] Sent: Thursday, April 15, 2010 11:53 AM To: Frank Girardi [EH] Cc: Casey Kipf Subject: RE: 2500 Navy Drive -City of Stockton Regional WastewaterControl Facilty Hi Frank, As per our conversation this morning, please see below for a description of our well completion details. Please let me know if you have any questions. Thank you very much! Three shallow monitoring wells and one deeper monitoring well will be installed at the Site. The monitoring well borings will be drilled using ten-inch outside diameter, continuous-flight hollow-stem augers. Drill cuttings will be spread in the vicinity of each monitoring well. All down-hole drilling equipment will be steam cleaned prior to use in each well boring. The three shallow monitoring well borings will be drilled to a total depth of approximately 9 feet below ground surface. The shallow monitoring wells will be constructed with five feet of four-inch outside diameter, Schedule 40, flush- threaded, machine-slotted polyvinyl chloride (PVC) screen (0.010-inch slot size) . A flush-threaded PVC bottom cap will be placed at the bottom of the screen section in each of the wells. Blank PVC casing will be installed above the screens to the ground surface. A filter pack of #2}12 or equivalent washed sand will be placed in the annular space to approximately one foot above the screens in each well while the augers are in place. The depth of sand in the annulus of each well will be monitored with a weighted tape measure while the sand is being placed and the augers are being gradually retracted to avoid bridging. The wells will be surged to settle the sand pack, if conditions allow, and additional sand added as necessary. To form a protective seal, approximately two feet of bentonite chips will be installed above the sand in the wells. The bentonite chips will be installed as the augers are retracted and will be hydrated using potable water. After the bentonite chips have hydrated, a surface seal of Type I/II neat cement containing less than 5% bentonite powder will be poured into the annulus of the wells and will extend from the bentonite to the ground surface. The deeper monitoring well boring will be drilled to a depth of approximately 20 feet below first encountered ground water anticipated to be at an approximately depth of five to seven feet below ground surface. The total well depth is estimated to be approximately 25 to 27 feet below ground surface. The monitoring well will be constructed with ten feet of four-inch outside diameter, Schedule 40, flush- threaded, machine-slotted PVC screen (0.010-inch slot size) . A flush-threaded PVC bottom cap will be placed at the bottom of the screen section of the well. Blank PVC casing will be installed above the screen to the ground surface. A filter pack of #t/12 or equivalent washed sand will be placed in the annular space to approximately two feet above the screen while the augers are in place. The depth of sand in the annulus of the well will be monitored with a weighted tape measure while the sand is being placed and the augers are being gradually retracted to avoid bridging. The well will be surged to settle the sand pack, if conditions allow, and additional sand added as necessary. To form a protective seal, approximately four feet of bentonite chips will be installed above the sand in the wells. The bentonite chips will be installed as the augers are retracted and will be hydrated by groundwater in the boring. After the bentonite chips have hydrated, 4/15/2010