Underwater and Terrestrial RI/FS at the Former Fort Custer Recreation Area/Industrial Area, Calhoun and Kalamazoo Counties, Michigan

Under a performance-based task order, HGL was tasked with completing an RI/FS, a Proposed Plan, and Decision Documents for four munitions response sites (MRSs) comprising the Eagle Lake Burial Area, grenade courts, and suspected and known rocket/artillery ranges and bomb targets at the former Fort Custer. The 1,500-acre site was used for training from World War I through the Korean War and now consists of industrial and recreational areas. The recreational area receives over 60,000 visitors annually and is used for boating, swimming, and hiking, with more than 25 miles of multiuse trails.

Depiction of Grenade Court circa 1940s Before Eagle Lake Expansion and Isolation of Island
Underwater DGM Surveys over 100 Acres of Eagle Lake

HGL performed an underwater and terrestrial MMR RI that included AGC using man-portable vector (MPV) and MetalMapper 2×2 advanced geophysical sensors, DGM using an EM61 metal detector, and extensive underwater DGM, which required diving and deploying remotely operated vehicles (ROVs). In the process HGL completed over 85 acres of waterborne DGM, 150 acres of side scan sonar, ROV inspection of over 100 anomalies, and underwater intrusive investigation of 150 anomalies. Through historical photograph analysis, HGL positively identified an artillery range fan and then refined the direction of fire based on field investigation findings.

Intrusive results show that Eagle Lake and its eastern bank were mixed-use target areas that received fire from Stokes mortars, hand grenades, and 37mm and 75mm shrapnel projectiles. Target areas were extremely well defined with high confidence for follow-on remedial action phases. HGL reduced immediate risk along the multiuse trails within the target areas by clearing them of munitions, and raised MEC safety awareness by working closely with the volunteers who maintain the trails.

Project Highlights
Completed over 100 acres of waterborne DGM and UXO diving operations to characterize two underwater MRSs. Conducted AGC and DGM for 30 miles of transects and grids to characterize three land MRSs.
Addressed multiple types of munitions including 20- and 100-pound practice bombs, 37mm and 75mm projectiles, 3- and 4-inch Stokes mortars, 2.36- and 3.5-inch rockets, practice antitank landmines, and Mk2 grenades.
Explosively destroyed nine MEC items on site and disposed of over 2,700 lbs of material documented as safe (MDAS) off site.
Received CPARS ratings of “Exceptional” for Schedule, Management, and Regulatory Compliance; and “Very Good” for Quality in the 9/6/2018 interim evaluation.