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May/June 2003: The Military Engineer
Fort Ord, a U.S. Army Base near Monterey, CA, was a major training and staging facility for infantry troops from its opening in 1917 until its closure in 1993. Since 1917, portions of Fort Ord were used by infantry units for maneuvers, target ranges, and other purposes. Ordnance and explosives (OE) were fired into, fired upon, or used on the facility in the form of artillery and mortar projectiles, rockets, and guided missiles, rifle and hand grenades, land mines, bombs, demolition materials, and small arms.
The historical range assessment was designed to investigate ranges and training areas for possible chemical contamination related to all types of OE including small arms. The evaluation of historical ranges utilized the 'conceptual site model' (COC) process to build an understanding of the site conditions and possible contaminated areas.
A 1996 'Record of Decision' was signed by the Army and regulatory agencies that specifies cleanup levels for primary COCs. Lead, antimony, and copper are the primary COCs related to small arms training. Explosive compounds, metals, and hydrocarbons could be present in areas where OE and OE related training occurred. Over 200 areas at Fort Ord have been identified as potential ranges or training areas. Many of these areas were used as far back as the 1920s and are now overgrown with vegetation or have been subsequently developed.
Range Investigation Process
The overall range investigation process developed for Fort Ord consisted of three phases -- site assessment, remedial investigation and remediation. This article discuss the Site Assessment phase and its three parts: Literature Review, Site Reconnaissance and Mapping, and Site Investigation Sampling.
A review of existing literature was the first step in evaluating areas at Fort Ord for the presence of ranges and training areas that could contain COCs related to OE use and training. Review of the data and development of the initial conceptual site model was completed in March 2002. Documents that were reviewed included installation document files including range usage logs, standard operating procedures (SOPs), dud records, OE contractor after action reports, historical and current aerial photographs, historical training maps, and interview records. Selected data from the review were integrated into the project GIS.
A process for the integration of historical information into the GIS was developed to track and aide in the review of existing information. The integration process involved the digitization of range features (historical fans and firing points), and other features, georeferencing of historical aerial photographs, and the integration of Computer Assisted Design (CAD) files generated by the OE removal contractor into the GIS. A series of SOPs were developed to standardize the process of adding information to the GIS. Procedures for the following data collection techniques were developed:
The GIS data were then reviewed, in conjunction with other data, to search for evidence of previous training areas and ranges such as historically disturbed areas, vegetation patterns, man made structures, range fans, targets, trenches, and bunkers. The digital information stored in the project GIS greatly aides in the identification of historical ranges and training areas at Fort Ord by allowing the viewing of historical aerial photographs and range features within a common coordinate system and scale as overlays and in conjunction with present day features. Based on this additional information the conceptual site model was updated.
As part of the literature review, 33 historical areas at Fort Ord were identified for no further investigation and 74 areas were recommended for site reconnaissance.
Site Reconnaissance and Mapping
Conducting a site reconnaissance was the second step in evaluating areas with potential contamination. Prior to beginning the field reconnaissance, a base map for each area was developed. Current aerial photography is available for all of Fort Ord and was used as the base map for each area that required reconnaissance.
Information that was presented on the maps was generally available within the project GIS and included range fan designations from historical training maps, specified training areas, locations of reported OE incidents, topography, and current roads and buildings. Maps using historical aerial photographs were also prepared to aide in selecting historical range features and limits.
Before the site visit was initiated, longitude and latitude data for key historical features such as training area boundaries, disturbed vegetation areas, target berms, and historical roads and trails, (waypoints) were loaded into a GPS unit. These points were then located to in order to establish that the area investigated corresponded to the area identified on the base map. During site reconnaissance the following features were typically mapped and recorded with the GPS.
In addition to mapping conducted using the GPS, notes were taken describing the vegetation type, general topography, condition of targets encountered, and buildings and other structures present.
The data collected in the field was then loaded into the project GIS for evaluation to determine whether sampling is required to further characterize a training site or range. Twenty-seven historical areas have been identified for site investigation sampling based on the literature review and site reconnaissance conducted.
Site Investigation Soil Sampling
If the results of the site reconnaissance and literature review indicated the potential for chemical contamination, SI soil samples were collected. Discreet, composite, or a combination of discreet and composite samples may be collected. To date discreet samples have been collected. The number and locations of samples collected, and analysis performed, is based upon:
Sampling at Fort Ord is ongoing.
The historical range assessment process developed for Fort Ord has been successful in developing the conceptual site model for identifying small arms and multi-use ranges and training areas at Fort Ord that could contain chemical residue.
The process has been very successful at identifying ranges and training areas from the 1940s and 1950s that are no longer evident due to vegetation growth and/or development. Features identified on historical aerial photographs and training maps, have been successfully reacquired and located through use of the waypoints for navigation. The preliminary results of the SI sampling indicate that a biased sampling approach based on the results of the literature review and reconnaissance activities is appropriate for initial site characterization.
Return to: 2003 Feature Stories