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VanDyke Dick From: VanDyke_Dick Sent: December 08, 1999 4:06 PM To: 'Marcus Pierce' l ^ P�, i I Cc: rallen@exchangeOl.ddc.dla.mil; david.a.sheets.maj@hnd0l.usace.6rmy. Il; john.nohrstedt@hnd0l.usace.army.mil; michael.w.williams@hnd0l.usace.army.mil; Sharpe_Graham; Vandewiel_Stephen; Thomas—Michael Subject: RE: SHAD Well 2 Abandonment Marcus --Thanks for your comments. I have added brief responses below. We also received a few comments from Harlin Knoll of San Joaquin County Environmental Health,which I have summarized here also. FYI --We just received notice from Huntsville Corps of Engineers that we are to "re-suspend" certain efforts (including the Well 2 abandonment) until further notice; therefore,the preparation and submittal of formal responses to comments will be delayed, as will the start of the well abandonment field effort. I'll keep you and Harlin informed (I'll also mail or fax this message to Harlin). Comments from Harlin Knoll are summarized as follows (with responses in parentheses): • Calculate grout volume (in gallons) needed to fill the casing to 290 feet bgs. (Volume=approximately 2,475 gallons) • Calculate PSI of the pressure grouting at the screen intervals and at total depth. (Pounds per square inch pressure is approximately 1 PSI per foot below grade, therefore, estimated pressures at screen intervals and TD would be approximately 124, 179, 199 and 290 PSI.) • The casing diameter/depth information documented on the SHAD Well 2 data sheet is misleading. (Casing diameter and depth should be 18-inch casing from ground surface to 30 feet bgs, and 14-inch casing from 30 to 290 feet bgs.) • After casing is cut off 2 feet below grade, make sure grout is placed in a "mushroom-shaped" area about 2 feet surrounding the well. (Comment will be followed during abandonment.) ---Original Message----- From: Marcus Pierce[SMTP:PierceM@rb5s.swrcb.ca.gov] Sent: December 03, 1999 1:12 PM To: dick_van_dyke@radian.00m Cc: rallen@exchangeOl.ddc.dla.mil;david.a.sheets.maj@hnd0l.usace.anny.mil;john.nohrstedt@hnd0l.usace.army.mil; michael.w.williams@hnd0l.usace.army.mil;Graham_Sharpe@radian.com;Stephen_Vandewiel@radian.com Subject: SHAD Well Abandonment I finished reviewing the video/Work Plan. Your general approach to the abandonment is fine, but I need more information on some of the procedures that you will be using. Please address the following questions/comments: 1. How did you come up with the perforated intervals? These intervals do not span the entire coarse sand intervals noted on the well log. Your October 20, 1999 memo suggests that you determined these intervals f,1m the video, but I found the casing very difficult to see below a depth of about 60 feet because of all the scale and floating debris. [VanDyke_Dick] Perforated intervals were identified by the Layne Christensen field supervisor during the recording of the downhole video. 2. There was no map provided with the work plan, so where is SHAD Well 2 located? Is this well actually PW-039 as the Water Management Report indicates? If not, refer me to a figure in our files that shows the location. [VanDyke_Dick] SHAD Well 2 is not PW-039, as shown in the Water Management Report, but is located approximately 600 feet southwest of PW-039 near the south edge of the North Balloon; a map showing the well location will be included with the formal written responses to comments. 3. The Work Plan does not specify how long you will maintain pressure on the grout to allow the cement mixture to set in the filter pack/formation outside the well screen (see DWR Bulletin 74-81, Page 56, Item#6). [VanDyke Dick] As stated in DWR Bulletin 74-81, "pressure shall be maintained for a length of time sufficient for the cementing mixture to set";for specific lengths of time, Radian will consult with the drilling contractor that performs this work to assure appropriate pressure times based on the grout composition; however, in our estimation, we anticipate pumping grout in three stages, with each stage to approximately 10 feet above a screen interval and maintaining pressure for at least 15 to 30 minutes at each stage. 4.The Work Plan states that "additional grout will be added to the casing if any settlement occurs". This is absolutely essential to providing a good seal, so how will you determine that the grout has stopped settling? I am concerned that Gregg Drilling will demob from the site before the grout has settled completely. [VanDyke_Dick] The level of the top of the grout will be checked following the initial grout placement and "topped off", if needed by either the drilling subcontractor, or if already demobilized from the site, by Radian technicians (up to 2 to 3 days following the initial grout 1