2.0 STATIC TEST This section describes the objectives, procedures, and results of the Static Test completed at Fort Ord, California, as part of the ODDS. 2.1 INTRODUCTION AND PURPOSE The Static Test, the ODDS first phase, consisted of collecting digital geophysical survey data in free-air over selected inert OE items at incrementally greater depths. This was accomplished by constructing a nonmetallic test stand approximately 10 feet high with mechanisms to suspend OE items at different orientations and depths (within 1/32 inch) below the surface of the stand. Inert ordnance items typical of Fort Ord were used during the Static Test. Pictures of these items, the test stand and the Static Test operations are provided in Appendix A. The Static Test was conducted between June 2 and June 23, 2000 at Fort Ord using four geophysical detectors, 1) EM61, 2) EM61-HH, 3) G-858, and 4) GEM-3 as proposed in the ODDS Work Plan (USA Environmental Inc., May 2000). 2.1.1 Objectives The objectives of the Static Test were to determine, establish, and document: 1. The range of detector readings indexed by OE item depth, orientation and detector type. 2. Free-air detector readings and signal profiles over OE items at a variety of incremental depths. 3. The range of detectable depths and horizontal distances for typical OE items found at Fort Ord using different types of detectors. 4. Baseline capabilities for mature-, new- and emerging-technology detectors, without interference from variable ground surface and soil conditions, compared to detectors currently in use at Fort Ord. 2.1.2 Background The Static Test was conducted using the four detectors identified by the USAESCH OE Center of Expertise as having potential for OE detection at Fort Ord. A full description and rationale for selecting these detectors appears in Appendix E of the ODDS Final Work Plan (USA Environmental Inc., May, 2000). The selected systems represent a range of technologies that have consistently provided the highest probability of detection (PD) and lowest false alarm rate (FAR) on ordnance test grids and live sites. Each has proven effectiveness in detecting and locating buried OE items. Detector Manufacturer and Model Type 1. Geonics Model EM61 (TDEM) 2-1 ODDS REPORT 2. Geonics Model EM61-HH (TDEM) 3. Geometrics Model G-858 (Cesium Vapor) (Magnetometer) 4. Geophex Model GEM-3 (40 cm coil) (FDEM) All of these instruments are man-portable and provide spatial response data as the detector is moved over an object. Positional data can be collected by three different methods: (1) continuous mode, whereby the data are collected on selected time intervals and the operator marks the data based on positional fiducials and the data are fitted to a known distance; (2) wheel mode, whereby the digital data are collected and marked by the turning of a survey wheel attached to the instrument; and (3) GPS mode, whereby the detector and GPS positional data as well as the sensor data are collected on selected time intervals. All of these methods allow for the development of two-dimensional analysis as well as generating line profiles from the collected data. Data collected from these instruments provides information on the capabilities for “families” of instruments that measure a specific physical property (such as magnetic gradient, total magnetic field, etc.) by means of recording a digital signal response. These four instruments were used as examples for families of equipment that measure either a single time window of a time domain EM response (EM61), two or more time windows of a time domain EM response (EM61-HH), total magnetic fields and magnetic field gradients using cesium vapor sensor technology (G-858), or frequency domain EM response (GEM-3). Analog instruments such as the Schonstedt were not used during the Static Test since there is no consistent method for determining the magnitude and shape of the response. However, analog instruments were used during the Seeded Test and Field Trial Site phases of the ODDS. 2.2 ORDNANCE USED IN STATIC TEST A total of sixteen OE items were used during the Static Test. Table 2-1 is a list of the OE items tested and the dimensions, weights and depth of penetration in sand for these items. [It should be noted that, for the sake of brevity and consistency, shortened descriptions of OE items have been used throughout the document. The full description of the OE items can be found in the Acronyms and Abbreviations section at the end of the table of contents.] All but two of the OE items were inert items obtained from previous OE investigations at Fort Ord. The 105mm and 155mm inert projectiles were collected from Fort Irwin, CA. Most of the items were rusted but in good, intact condition. Pictures of the OE items used in the testing are presented in Appendix A. The categories in Table 2-1 are discussed in Section 2.5.1. 2-2 ODDS REPORT Table 2-1 Characterization of OE Items Used in Static Tests Ordnance Detection and Discrimination Study Fort Ord, California ODDS REPORT Depth of Depth of Diameter Length Weight Penetration Penetration Ordnance Item (Inches) (Inches) (lbs.) In Sanda Plus One Footb Categorye 14.5mm Projectile 0.57 2.55 0.152 0.2 1.2 II 22mm subcaliber 0.87 7 0.625 1.4 2.4 III 35mm Subcaliber 0.75 7.5 0.32 0.5 1.5 II 37mm Projectile 1.46 4.5 1.75 3.9 4.9 V M9/M11 Grenade 2.25 3.5 1 0.1 1.1 II 60mm Projectile 2.36 7 4.25 1.1 2.1 III 2.36-inch Rocket 2.36 19.5 3.25 0.4 1.4 II 75mm Projectile 3 11 12 3.9 4.9 V 81mm Projectile 3.18 11 5.25 2.7 3.7 IV f 2 81mm Illumination 3.18 25 10.7 NA NA IV - 3 3.5-inch Rocket 3.5 23.6 9 0.8 1.8 II Signal Illumination Flare 1.5 10 0.53 0 1 I 90mm Projectile 4 9.5 22.3 2 3 III d 105mm Projectile 4.13 16.8 NA 7.7 8.7 IX d 155mm Projectile 6.1 26.93 NA 14 15 X Stokes Mortar 3 14 8.25 3.3 4.3 V MKII Grenade 4.75 4.75 1 0 1 I a Penetration Depths were taken from Table 4.1-1 of the Former Fort Ord Phase II EE/CA, April 1998. b Includes a one foot cover of post deposition material c Category of munitions determined by rounding up to the nearest foot d Used smoke OE Item to simulate shape of high explosive version of item. e See Section 2.5.1 of text. f Category depth for 81mm Illumination based on potential penetration of “dud” item NA - Data not available 2.3 STATIC TEST PROCEDURES The following subsections describe the Static Test area setup, test stand construction and test procedures. 2.3.1 Static Test Area Before placing the Static Test stand in the test area, the OE contractor, USA, performed a magnetometer clearance of the entire area removing detected metal debris to a depth of four feet. Hand-held magnetometers (Schonstedt Model GA-52/Cx) were used in the clearance process. Ferrous metallic items detected using the Schonstedts were removed from the area. During the clearance process, a number of live UXO items were identified and detonated in place. A work plan variance was developed as the presence of UXO affected the Static Test schedule originally proposed in the Work Plan. Work plan variance forms are provided in Appendix B Tab 4. Following the clearance by USA, EM61 and G-858 magnetometer surveys were conducted over the test stand area. Seventeen EM and two magnetometer anomalies were identified, located in the field, and intrusively investigated. Metal sources were removed. Results of the investigation are presented in Appendix B Tab 6. Once identified anomalies were removed, the test stand was placed with the longest dimension of the stand oriented in a magnetic north-south direction. 2.3.2 Test Stand Construction The test stand was constructed entirely of a nonmetallic, nonconductive polymer (see Appendix B Tab 5 for specifications). All supporting beams, the floor of the stand, bolts, and nuts were also of polymer material. A polymer frame and ordnance holder were constructed to allow the raising and lowering of the OE test items at fixed distances or intervals from the sensors. The dimensions of the deck were approximately 8 feet wide and 12 feet long and it was elevated approximately 10 feet above ground surface. Photographs showing the Static Test stand are presented in Appendix A. Before Static Testing was performed, conductivity and magnetic response measurements were taken on the stand platform to ensure that the construction materials were non-responsive to the instruments being tested. Responses were within the background range of the instruments. Three 8-foot long profile lines were marked on the platform, with fiducial marks at the start, middle and end of each line. The centerline was positioned directly over the center of the platform; two profile lines were located 2 feet on either side of the centerline profile. The center of the ordnance holder was constructed so that the center of the holder was located directly under the mid-point of the centerline. A work plan variance (see Appendix B Tab 4) was prepared to describe two modifications to the test procedures because of stand construction limitations. Originally, the side profiles were to be spaced 2.5 feet on either side of the centerline; however, 2-4 ODDS REPORT because of the addition of safety side rails on the platform the profiles were located on 2-foot centers.