## TECHNICAL MEMORANDUM Removal of Pride Hangar SVE System

Tech Memo: Removal of Pride Hangar SVE System, Ver. 1 Page 1 of 2 Ellsworth AFB/ACC 4-Base PBC: FA8903-04-D-8679, DO 0053 I:\ACC 4 Base\Ellsworth\5. DELIVERABLES (BASEWIDE OR MISC)\5.5 Misc Tech Memos\5.5.4 Pride Hangar SVE\TM_PH SVE System Removal_ver1.doc 5/6/10/OMA To: Ellsworth Air Force Base Remedial Project Managers

From: URS Group, Inc.

Date: May 6, 2010
Subject:Removal of Pride Hangar SVE System



### 1.0 Purpose The purpose of this technical memorandum is to document the removal of the Pride Hangar soil vapor extraction (SVE) system from the northwest corner of the Pride Hangar and recommend abandonment of the eight SVE wells associated with the system. 

### 2.0 Background A recommendation to implement SVE at the northwest corner of the Pride Hangar was made by Earth Tech in 2003 (Earth Tech 2003). This action was implemented and consisted of SVE pilot testing in May 2004 and intermittent operation of the system from July to November 2004. Implementation consisted of installation and operation of eight SVE wells as temporary wells (grouted to the surface but without surface protection). These temporary SVE wells are screened in the vadose zone to the water table surface. The system was shut down November 15, 2004 and has not operated since that time. In 2005, Earth Tech recommended “that the SVE system is not re-started until further ground water treatment progress is made” (Earth Tech 2005). This recommendation was made due to the potential aeration of ground water and its detrimental effect on anaerobic ground water treatment implemented in 2004 (Earth Tech 2005). The SVE system (blower, piping, and protection fencing) remained in place for possible placement back in operation. Related to this SVE system, an ESD was drafted for OU-11 in 2004 that included language to document implementation of SVE technology at this location and the ESD was never finalized. An ESD was completed for OU-11 in May, 2007 (USAF 2007) that proposed implementing the SVE system “if needed”. In April 2010, the USAF requested that the surface piping, SVE blower system, and cattle panel fencing be removed. The system was no longer used, had deteriorated over time, and was now a minor safety, obstruction, and appearance issue on the flightline. This issue was discussed on the April 13, 2010 RPM teleconference and removal of the system was reported on the April 26, 2010 teleconference. URS personnel removed the system between April 15 and 21, capped the eight SVE wells, and moved the blower to Building 6905 for storage. The location of the SVE system at the northwest corner of the Pride Hangar has been the focus of several injection events. Emulsified soy oil and culture was injected in 2004 (Earth Tech 2005), sodium lactate was injected in 2005 (URS 2010), and this site is one of the IRT treatment zones injected in 2007 and 2008 by URS as PH-IRT2 (URS 2010). All of this injection work was

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## TECHNICAL MEMORANDUM Removal of Pride Hangar SVE System

Tech Memo: Removal of Pride Hangar SVE System, Ver. 1 Page 2 of 2 Ellsworth AFB/ACC 4-Base PBC: FA8903-04-D-8679, DO 0053 I:\ACC 4 Base\Ellsworth\5. DELIVERABLES (BASEWIDE OR MISC)\5.5 Misc Tech Memos\5.5.4 Pride Hangar SVE\TM_PH SVE System Removal_ver1.doc 5/6/10/OMA completed by direct push method with the exception of injection into three monitoring wells located inside the Pride Hangar building in 2008.


### 3.0 Recommendation URS recommends that the eight SVE wells be abandoned at this site. Since these SVE wells were screened in the vadose zone, they could not be used as injection points. This site is an effective and active IRT treatment zone and anaerobic groundwater conditions are required for continued treatment. Therefore, URS believes any aeration at this site such as SVE would be detrimental to the IRT process. There are six monitoring wells at this location outside the Pride Hangar building plus three additional wells located just inside the building that are available for injection and site monitoring.


### 4.0 References Earth Tech. 2003. Serial Letter 1-54-RA-301 to U.S. Army Corps of Engineers, Pride Hangar Source Remediation Recommendation, Ellsworth AFB, South Dakota. September 3. Earth Tech. 2005. Serial Letter ERS-3-RA-158 to U.S. Army Corps of Engineers, Pride Hangar Source Area Treatment/Updated Work Plan, Ellsworth AFB, South Dakota. February 21. U.S. Air Force. 2007. Explanation of Significant Differences to the Record of Decision for Operable Units 1, 2, 3, 4, 5, 6, 7, 8, 11, and 12. May 1. URS. 2010. January through March 2010 RAO Report, Ellsworth AFB, South Dakota. April 19.

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