Interim Guidance on the Use of SiteStat/GridStats and Other Army Corps of Engineers Statistical Techniques to Characterize Military Ranges

United States Environmental Protection Agency
Washington, D.C. 20460
January 19, 2001
Office of Solid Waste and Emergency Response

MEMORANDUM

What is the purpose of this guidance?

EPA and the U.S. Army Corps of Engineers (USACE) are currently engaged in a review of several geophysical field sampling, exposure characterization, and analytical techniques employed by the USACE for military ranges. These include SiteStats (OS), UXO Calculator, and Ordnance and Explosives Cost Effectiveness Risk Tool (OECert). EPA's National Environmental Research Laboratory (NEE) Technical Support Center is leading the EPA review with assistance from my Office and several EPA Remedial Project Managers currently working on ranges. The purpose of this memo is to inform you of concerns regarding these techniques, provide a list of installations and FWS where SiteStat/GridStats (SS/GS) have been used, and to provide direction on communicating with the public on the use of these "tools" by USACE.

What are EPA's concerns?

A NERL staff and EPA Regional Project Managers have expressed concern relative these techniques and the site-level conclusions reached using them. These concerns, some which are listed below, form the basis of the joint EPA and USACE review of these tools.

• the ability of SS/GS and UXO Calculator to locate Unexploded Ordnance (UXO) clusters e.g., target impact areas) and the boundaries of UXO contaminated areas;
• whether the assumption of homogeneity of UXO used in these techniques is valid;
• the extent to which an area is classified as "homogeneous;"
• the statistical validity of assessing sector non-homogeneity;
• the consistency/reproducibility of results;
• a problem in the algorithm and confidence intervals for UXO Calculator;
• variability in UXO estimates and exposure scenarios.

NERL's draft final report was distributed to a small number of regional RPMs that are providing input for the review. Unfortunately, it was pre-maturely distributed broadly and may be labeled as "final". This is not the case. This report is not "final" as EPA and USACE are still refining the analysis and are working jointly on a number of action items.

While EPA is continuing to work with the USACE in evaluating these issues, including a more thorough examination of OECert, Regions should continue to work with the USACE on a site specific basis to verify the appropriateness of the statistical assumptions of the models used and the results.

How does USACE indicate SS/C'S and other tools should be used?

The USACE is careful to note that these statistical methods are only one of several potential tools used in the site characterization process. They are typically used where there is historical evidence of ordnance/explosives (OE) use and where they believe exposure to UXO or military munitions is possible. Due to the large acreage of many ranges, these techniques were devised to minimize sampling and cost, not maximize detection of UXO or UXO-related anomalies. SS/GS were originally developed for use with "mag and flag" operations and should be viewed as a tool to plan response actions and to predict impacts (UXO threat reduction) from conducting a response. UXO Calculator can be used with newer digitally recorded and georeferenced geophysical techniques. It was developed to streamline the SS/GS software processes and establish upper and lower confidence limits. Despite the need for better documentation and some problems in the software, NERL has found the UXO Calculator to have some technical merit for assessing confidence levels on UXO density, however, more work is needed on the sampling techniques used (i.e., grids, meandering path, etc.) and the statistical assumptions on which they are based. How this translates to field application has not yet been evaluated. OECert is Considered to be a tool for assessing UXO exposures rather than risk assessment. OECert is being used by USACE to quantitatively rank alternatives for exposure reduction.

What should EPA Regions do?

My Office has developed a listing of DoD installations and Formerly Utilized Defense Sites (FUDS) is known to have been used. You are cautioned that the list (attached) may not be inclusive. Your Regional programs may have been involved at some of these sites, I want you to especially note that there are a number of Fast-Track BRAC installations on this list. Ranges on these BRAC facilities may have been already transferred or may be scheduled for transfer. Transferees or potential transferees should be informed of EPA’s concerns on the statistical sampling methods used and of the ongoing review. Regions should note that no definitive conclusions have been reached.

Transferees, potential transferees or property owners should be informed that, depending on a variety of factors, SS/GS may not accurately estimate the presence of UXO in a given area and must not be solely relied upon to make property transfer decisions. Rather the entire USACE or Component site characterization and decision-making process needs to be carefully considered (eg., information from Archive Search Reports (or Investigation Progress Reports (INPRs) for FUDS, installation operational history, interviews, visual inspections, actual geophysical sampling, response/clearance activities, site investigation reports, and other investigative reports, etc.).

At installations or FUDS where an EPA Region is providing oversight and these techniques have been or are being used, the Region should ensure that the USACE properly applied SS/GS for estimating the UXO density on ranges or other UXO sites (e.g., OB/OD), for which, the programs were designed. (If a state is providing oversight of FUDS with a former range or with the potential of exposure to UXO or military munitions, please make them aware of EPA's concerns, the ongoing review and the fact that no definitive conclusions have been reached.)

Our Office recommends that UXO geophysical sampling or site characterization designs be based upon site-specific information, including historical data, aerial photography, site reconnaissance, and other preliminary data that indicates a former range or other UXO site. Particular scrutiny should be used where SS/GS was used as the sole criteria for the determination of no further action or limited response action. The predictions made by SS/GS to areas that were not ranges or other UXO sites may or may not accurately indicate the presence of UXO. USACE acknowledges these methods were not designed to detect areas such as ordnance burials and OB/OD disposal units, and the presence of these sites must be determined by other methods.

As work proceeds on this effort, my office will keep you informed on the progress. If you have any questions, please contact my office at 703-603-0048.

Attachment

Attachment - Installations and facilities where Site Stats/Grid Stats have been used.

1. Adak Naval Air Facility, AK - BRAC
2. Attu Island, AK
3. Dutch Harbor, AK
4. Southwest Proving Ground, AR
5. Baywood Park Training Area, CA
6. Benecia Arsenal, CA
7. Camp Elliott, CA
8. Fort Ord Phase 1 and 2, CA - BRAC
9. Mare Island Naval Shipyard, CA - BRAC
10. Mission Trails, Tierrasanta
11. Salton Sea Test Range, CA - BRAC
12. Buckley Bombing Range, CO
13. Brooksville Turret and Gunnery Range, FL
14. Waikoloa Maneuver Area, HI
15. Camp Grant, IL
16. Illinois Ordnance Plant, IL
17. Camp Claiborne, LA
18. Fort Devens, MA - BRAC
19. Fort Richie, MD - BRAC
20. Jefferson Barracks, MO
21. Fort Hancock, MS
22. Camp McCain, MS
23. Diamond Springs Road, Helena, MT
24. Camp Greene, NC
25. Duck Target Facility, NC
26. Blaine Naval Ammunition Depot, NE
27. Sioux Army Depot, NE
28. Fort Hancock, Sandy Hook, NJ
29. Raritan Arsenal, NJ
30. Fort Wingate, NM - BRAC
31. McGregor Range, NM
32. Umatilla Depot, OR - BRAC
33. Camp Croft, OOU6, SC
34. Former Motlow Range, TN
35. Camp Howze, TX
36. Camp Maxey, TX
37. Castner Range, TX
38. Pantex Ordnance Plant, TX
39. Fort Monroe, VA
40. Nansemond Ordnance Depot, VA
41. Camp Bonneville, BA - BRAC
42. Dolly Soda Wilderness Area, WVA
43. Pole Mountain, WY
44. Culebra Wildlife Refuge, Puerto Rico
45. Badlands Bombing Range, SD
46. Camp Gordon Johnson, FL
47. Former Honey Lake Demo Range, CA
48. Molakai Bombing Target, HI
49. Sudbury Annex, MA - BRAC
50. Fort Totton, NY - BRAC
51. Former Boise Army Barracks, ID