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COTTER CORPORATION (N.S.L.) <br />RESPONSE TO DRMS LETTER DATED SEPTEMBER 9, 2011 <br />Additional information requested by DRMS: <br />10 /11 /11 <br />1) Request: A list of installation dates for all sumps installed pursuant to Technical Revisions <br />TR -12 and TR -15. <br />Response: Historic Sump 1 was refurbished under TR -12. Refurbishment of historic Sump <br />4, and conversion of historic Monitoring Well MW -9 to a pumping well, was completed prior <br />to the issuance of TR -15 in a proactive attempt to improve groundwater capture using <br />existing site facilities. The initial infrastructure used for these extraction locations did not <br />require changes to the permitted /affected area (all piping and electrical infrastructure was <br />temporarily placed on the ground surface). All other groundwater collection systems have <br />been developed under TR -15. <br />The October 7, 2010 approval letter for TR -15 indicated that "...Cotter's current plan is to <br />install only one sump /French drain combination in the near term..." However, in addition to <br />TR -15 plans for installation of Sump 5, Cotter had also indicated plans to pump and treat <br />water from the existing pond in the vicinity of the former emergency overflow retention <br />pond. During subsequent dewatering efforts associated with other sump installations and <br />pipeline burial at the site, it was determined that an existing dewatering trench located <br />upgradient from the pond provided a unique opportunity for more effective capture of <br />groundwater responsible for the pond's formation. As a result, a minimally engineered sump <br />using available spare components and materials was installed at this location (this became <br />Sump 9). The bonding originally posted for direct pumping/treatment of pond water was <br />roughly commensurate with costs associated with subsequently modified plans to install a <br />minimally engineered extraction system at the alternate pumping location. <br />Prior to construction, DRMS was verbally informed of plans to also install the first of "three <br />additional sumps" (Sump 8) as described in the TR -15 approval letter. A check in the <br />amount of $109,000 to cover bonding for construction of Sumps 5 and 8, along with <br />pumping/treatment of pond water, was provided to DRMS in mid - October 2010. This <br />included $52,000 for Sump 5, $52,000 for Sump 8, and $5,000 for pumping/treatment of <br />pond water (later modified to become Sump 9 as described above). <br />Sump 10 was not a planned groundwater collection location. Concerns about potential <br />evaporative losses from the existing pond in this area led to a decision to backfill the pond <br />with available clean fill. During backfill efforts, a 48 -inch corrugated HDPE casing pipe, left <br />over from earlier sump construction activities, was placed at the eastern end of the pond in <br />order to continue monitoring groundwater levels and water quality in this area of the site. <br />After initial analytical water quality results from this location were obtained, a spare pump <br />was installed and spare piping was constructed above ground to temporarily enable pumping <br />from this location to the water treatment plant. Now termed "Sump 10 ", this extraction <br />location will be converted into an official, permanently winterized sump under TR -15 in <br />2 <br />