Draft Site Investigation Report for Operable Unit B-1

EXECUTIVE SUMMARY

Delivery Order No. 0083, Unexploded Ordnance Investigation of the Remote Areas of the Former Naval Air Facility (NAF) Adak, was intended to provide ordnance contamination data to support decisions on the ability to reuse Adak Island. This investigation was focused on all of Adak north of the Military Reservation Boundary, excluding the downtown area, which was investigated under previous delivery orders.

The Adak Remote Areas were investigated for ordnance contamination using the following methods:

Sector Selection - The SiteStats/GridStats methodology was used to determine the project sectors based upon geographic homogeneity, past use, and anticipated ordnance density. Historical archive records and documents were reviewed by unexploded ordnance (Munitions) personnel and aided in identifying the 26 distinct sectors that were investigated during the 1999 field season.
Terrain Analysis - Each sector was analyzed to identify the hazardous terrain. Areas steeper than 27.5 degrees were excluded from the investigation area. Demarcation of the Investigation Areas-Each sector was evaluated by SiteStats/GridStats to determine the sampling area required to statistically represent thesector. Waypoint maps were developed to identify investigation paths within these ctors, covering the required sampling area. These idealized pathways were adjusted in the field as necessary to accommodate site-specific terrain and vegetation or other physical features which may have limited access or posed a danger to field personnel.
Geophysical Survey and Target Selection-Subsurface anomaly data was collected over the selected areas using a time-domain electromagnetic instrument and processed to develop geophysical anomaly maps and target anomaly lists.
Anomaly Selection-Target anomalies were chosen for intrusive investigation using SiteStats/GridStats protocols for selected areas. Digital geophysical data was recorded, post-processed and analyzed to identify with an associated signal indicative of metallic wastes which may be ordnance related.
Intrusive Investigation-Selected target anomalies were excavated in order to identify and record findings of geophysical targets within 4 feet of the ground surface.

Mobilization to Adak for Delivery Order No. 0083 started on March 29, 1999. Following the site staff arrival, office setup, and training sessions, the geophysical data collection began on April 15, 1999. In order to prevent over-exertion of the geophysical personnel andpotential associated technical errors or injuries, four separate periods of data collection were performed with the last period ending on October 2, 1999. Munitions intrusive operations beganon April 17, 1999 and continued until October 28, 1999, with the field personnel rotatingoff-island for a rest period every 4 to 6 weeks on the average. Final demobilization occurredon November 11, 1999, with the departure all remaining staff from Adak. The following is asummary of results from investigation activities:

26 sectors were investigated
Geophysical teams walked approximately 594 miles while collecting data 216 acres were geophysically surveyed
7,243 anomalies were identified by interpretation of geophysical data
4,991 anomalies were intrusively investigated
114 intrusively investigated anomalies (targets) were made up of one or more
Munitions or abandoned ordnance and explosives (OE) items
67 Munitions or abandoned OE items were visually discovered on the surface.

The complete investigation results for each sector are provided in Appendices B through AB of this report. A map showing the sector location, track surveyed, targets located, and descriptions of some items found is provided for each sector. All data collection during the 1999 field season was done using a differential global positioning system (DGPS), ensuring accuracy of position data to within inches. However, existing background mapping data for Adak was not available with this level of accuracy. The existing data was shifted in order to better visually represent exact survey and investigation locations; however, the graphic depictions for some of the more remote areas remain slightly inaccurate. This in no way affects the validity or accuracy of the data collected, it simply makes it more difficult to accurately display the data in reference to the topography and landmarks on Adak.

An obstacle map is provided in each appendix to visually represent areas found to be inaccessible for data collection due to steep terrain or other physical limitations. During the planning phase for the 1999 investigation, an effort was made to identify steep areas and select a survey route which did not include inaccessible areas; however, the existing, relatively imprecise 20-meter contour interval topography maps for Adak did not reveal all hazardous and impassable terrain experienced by the geophysical teams and described on the obstacle maps.

A report for each anomaly intrusively investigated is also included in each sector's appendix. This data is taken from the Intrusive Investigation Data Forms completed by Munitions personnel during operations. Anomaly findings have been classified and grouped for statisticalpurposes.