A team from the U.S. Army Public Health Command traveled to McAlester Army Ammunition Plant, Okla., to sample groundwater at existing monitoring wells, install new monitoring wells and locate additional well sites. The field investigations were in support of the Resource Conservation and Recovery Act dealing with hazardous waste, and state requirements at MCAAP's Open Burn and Open Detonation operations and its fuel farm area.

"The goal of groundwater monitoring at the OB/OD and fuel farm areas is to detect potential contaminants migrating from the sites and mitigate any potential impact to human health and the environment," explained Beth Martin, USAPHC Ground Water Storm Water Program manager. "Groundwater migrating from both the OB/OD and fuel farm areas eventually discharges to nearby Brown Lake."

The fuel farm area stores gasoline and diesel fuels used for vehicles at MCAAP. Some petroleum spills have led to petroleum-impacted groundwater. Soil removal and ongoing groundwater monitoring indicate petroleum contaminants are being degraded by naturally occurring microorganisms.

"This was an opportunity to gain hands-on experience in field application of hydrogeologic principles," according to 1st Lt. Robert White, a USAPHC environmental science and engineering officer, who assisted with the investigations. "Our team used these principles for monitoring well-site selection, monitoring well drilling operations using auger and air rotary technology, and monitoring well construction."

"Evaluating the permeability of the surrounding aquifer, performing geophysical studies which measure electromagnetic fields and low-flow groundwater sampling methods at McAlester are performed using specialized equipment, operated by trained personnel," explained Mark Farro, USAPHC supervisory engineering technician.

"MCAAP operates one of the Army's largest OB/OD operations," according to Darrell Elliott, MCAAP's Environmental Management Office director. "These operations are used to destroy excess, off-specification and unserviceable munitions and energetic materials."

Regulatory requirements include monitoring of groundwater migrating from the sites. However, there are no guidance documents regarding monitoring well locations at OB/OD sites. Some of the challenges of locating and installing monitoring wells at OB/OD sites include potential unexploded ordnance, maintaining well integrity, site geology and depth to groundwater.

Many factors are involved in selecting monitoring well locations including calculating the minimum safe distances from the OB/OD units to avoid effects of airblast overpressure or ground vibrations. USAPHC experts also determine safe distances with respect to net explosive weight, wind velocity, air temperature and cloud cover. In addition, the location of utilities, the site geology, topography, and other hydrogeologic factors must be considered when determining well placement.

"The collaborative effort effectively supported MCAAP by fulfilling permit requirements," said Capt. Jorge Lopez, USAPHC Environmental Health Engineering Division manager. "This was a great learning opportunity and demonstrated the value of collaboration among the personnel at MCAAP and the USAPHC technical specialists."

"The monitoring of groundwater contaminant pathways is important to ensure contaminants are not discharged to surface water," said Elliott. "USAPHC has continued to provide valuable support to MCAAP in protecting human health and the environment through the use of innovative ideas and technology."