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July 7, 2005: Public Works.com


A public/private sector partnership is transforming a former military depot in Memphis, TN into a distribution and light manufacturing business park. Formerly known as the Defense Depot Memphis, Tennessee (DDMT), the Depot was opened in 1942 and is located on a 642-acre site in a residential and commercial area of Memphis. The Depot managed and furnished military general supplies to the U.S. Army and the Department of Defense (DoD) and several federal civilian agencies. The site, which once warehoused a wide variety of materials for government use including hazardous materials, is expected to generate both jobs and tax revenues for the City. At the present time, 73.5 percent of the leasable space is leased, and includes 29 tenants and jobs for 1,084 people. The team includes the Defense Logistics Agency (DLA), the U.S. Environmental Protection Agency (EPA), the Tennessee Department of Environmental Conservation (TDEC), along with MACTEC and other consultants. The team was instrumental in developing the technical and regulatory framework that has resulted in favorable environmental dispositions.

The site is divided into two properties -- the Main Installation, consisting of warehouses on 578 acres, and Dunn Field, an open area of 64 acres. DDMT¡¦s role was to receive, store, and ship various commodities for the U.S. Army and DoD under the auspices of DLA. DDMT was closed on Sept. 30, 1997 and subsequently became part of the Base Realignment and Closure (BRAC) process.

In 1995, DDMT was designated for BRAC. DDMT¡¦s environmental restoration program has been working nearly 10 years in an effort to expedite the transfer of property to the Depot Redevelopment Corporation. DLA retained MACTEC to join the restoration team as the program manager and remedial action contractor. This was also done prior to completion of the remedial design to allow enough time to perform constructability reviews during preparation of design, potentially mitigating schedule delays. The schedule has been expedited by preparing work plans in conjunction with the remedial designs, initiating the long-term monitoring prior to completion of the final remedies, and working closely with regulatory agencies. Key tasks have included:

  • Program Management: Since the BRAC Environmental Coordinator no longer physically resides at DDMT, principal consultant tasks includes primary interface with regulatory agencies and the Depot Redevelopment Corporation, management of program schedules, and oversight of all contracted activities.

  • Remedial Action: Includes implementing selected remedies as well as innovative remedial actions. Proposed actions include excavation and disposal, enhanced bioremediation using lactate, injection of zero-valent iron, installation of a permeable reactive barrier, monitored natural attenuation, and soil-vapor extraction. In fact, initial use of zero-valent iron injection was applied to the leading edge of the higher concentration of the off-site plume on Dunn Field and was completed in just seven months from the initial well through completion of injections.

  • Long-Term Monitoring: In an effort to position DDMT to support monitored natural attenuation as a final remedy, long-term monitoring of groundwater at the Main Installation was initiated.

  • Community Relations: An ongoing community relations program has been implemented, which includes serving as liaison with the Restoration Advisory Board, publishing twice-yearly newsletters, and maintaining the DDMT public website. One major issue that was successfully addressed involved iron injection into the ground. A public meeting spearheaded by MACTEC helped alleviate community concerns and included a presentation by an EPA research scientist.
DDMT History
Hazardous materials, such as flammables, solvents, petroleum/oil/lubricants (POL), paints, pesticides, herbicides, wood treating products, oxidizers, corrosives, and reactives were among the commodities used, stored, repackaged, and shipped at DDMT.

From 1940 to 1948, part of the southwest section of Dunn Field was used as a landfill for outdated or damaged foodstocks and supertropical bleach. Also, small amounts of hazardous substances (acids, mixed chemicals, and chemical agent identification sets) were buried in the northwest section. In 1946, DDMT became a disposal site for chemical warfare material (CWM), when 29 captured German mustard bomb casings were drained, neutralized, and buried. Originally these bomb casings resided on a train discovered to be leaking while traveling through Memphis to the Pine Bluff Arsenal.

Located under DDMT are groundwater aquifers, underground formations of sand and gravel that store and supply groundwater to wells and springs. The shallow aquifer, approximately 100 feet below ground level and known as the fluvial aquifer, was tested and found to contain chlorinated volatile organic compounds. However, the actual source of Memphis¡¦ drinking water lies 250 to 300 feet below ground level and was not impacted.

Remediation Efforts
Prior to DDMT's closure, restoration projects were already underway to identify, characterize and remediate environmental impacts. With the closure announcement, the restoration strategy has focused on property disposal, transfer, and reuse considerations, itemized as follows:

  • Defining environmental conditions and determining areas affected by past DDMT operations;
  • Developing an effective environmental cleanup program; and
  • Implementing effective cleanup activities while protecting residents and the environment.
The site is now being cleaned up under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA, commonly known as the Superfund). Initially the site was governed under both CERCLA and the requirements of the Resource Conservation and Recovery Act (RCRA). But by working closely with the Army Environmental Counsel, RCRA record keeping and permitting compliance was discontinued, thus saving the government compliance monies. The CERCLA cleanup process is comprised of six phases:
  1. Preliminary assessment and site investigation (PA/SI).
  2. Remedial investigation and feasibility study (RI/FS).
  3. Proposed plan development detailing how the site will be cleaned up.
  4. Record of decision (ROD.) The ROD is an agreement between the facility, the EPA, and TDEC and incorporates the proposed plan, goals, time schedule, and costs.
  5. Remedial design.
  6. Remedial action, which includes a monitoring plan that measures how well project goals are met.
The fifth and sixth phases are currently underway. Two key tasks in recent months have been installing new wells in Dunn Field in areas of higher chlorinated solvent impacts and excavating buried materials and associated soils at former disposal sites.

The entire property will be restored to state and federal health standards to be safe for industrial workers. The family housing area was cleaned up to residential standards and is currently used for veteran housing. The golf course will be used by the City for an after-school program.

The Main Installation cleanup, which consists of remediating groundwater solvent impacts, is scheduled for startup in late 2005. An enhanced bio-remediation process will be utilized where sodium lactate, a natural food additive, will be injected into the soil to enhance bacteria growth. The bacteria then will use the impacted groundwater as a food source, which will eliminate the solvents.

Two other integral tasks are being implemented. A "source areas cleanup" addresses solvents located in the soil down to the water level (e.g., 80 feet) and the cleanup of the solvents in the groundwater. The cleanup of soil will be accomplished though soil vapor extraction (SVE) and the SVE system will be maintained for five years to remove the impacts. Groundwater cleanup will be accomplished through injecting zero valent iron and the remediation will occur in the following few months to a year. Groundwater monitoring will continue until groundwater cleanup objectives are met.

The third Dunn Field remediation action will take place west of Dunn Field. It will include a permeable reactive barrier using a high concentration of zero valent iron (typically 30-100 % iron), as well as injection of zero valent iron in hot spots.

"The program objective is to expedite the transfer of former government-owned property to productive commercial and industrial use in Memphis," said DLA Environmental Program Manager Michael Dobbs. "This effort is increasing local jobs and the tax base for the City."

The transition from a military depot to a viable business park will yield significant environmental and economic benefits for the City. The team effort has minimized environmental impacts, met all state and federal safety standards, and resulted in both time and cost savings.

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