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Blackstrap Molasses Impacted Groundwater Clean Up

Federal Remediation Technologies Roundtable Technology Cost and Performance Enhanced In situ Biotransformation at the Weapons Industrial Reserve Plant, Dallas,

TexasSite Name:Naval Weapons Industrial Reserve Plant (NWIRP) Period of Operation: CleanupOctober 1999 - September 2000

Injection of diluted raw blackstrap molasses into impacted groundwater bearing zones 2 injection wells, one in the upper  (12 ft bgs) and one in the lower water-bearing zone (approximately 35 ft bgs) Injection and monitoring wells installed near center of TCE plume. Total of approximately 560 gallons of molasses injected into upper zone and 140 gallons into lower zone, over a period of two months- 13-52 gal. injected in upper zone and 0-35 gal. injected in lower zone per event Concentration of molasses ranged from 10-20 % Injection events occurred every 2-3 days  - Larger volumes of molasses (325-1,800gal. at 2% concentration) injected in latter stagesof demonstration to evaluate hydrodynamic effects ofcreating small groundwater mounds around injectionwells

Cleanup Authority:Not identified

Contacts: Site Lead
Greg Penland
2155 Eagle Drive, North
Charleston, SC 29406

Consultant David Vance
ARCADIS Geraghty & Miller, Inc.


Additional Contacts
Martha Araujo
1100 23rd Ave.,
Port Hueneme, CA 93043

Michael Maughon
EFD Southern
2155 Eagle Drive, North
Charleston, SC 29406

VOCs- TCE (26.5-5,300 µg/L) and daughter products, including 1,1-DCE, 1,2-DCE isomers, and vinyl chloride Waste Source: Unlined pits that received liquid wastes generated from the manufacture and assembly of military and commercial aircraft components and weapons systems

Type/Quantity of Media Treated:  Groundwater


Two water-bearing zones in study area  (unlined acid neutralization pit near Solid Waste Management Unit #15 that received liquid wastes from  site operations between 1970 and 1983) Depth of upper zone is 12 ft bags and  depth of lower zone is approximately 35 ft bags.   Literally and vertically anisotropic  and heterogeneous hydrogeology


- Hydraulic conductivity: upper water-bearing zone - 35.7 to 13.5 ft/day; lower   water-bearing zone - 29.0 to 2.2 ft/day; upper and > lower water-bearing zone (not separated) - 6.2 to  1.4 ft/day


Purpose/Significance of Application:


Evaluation of the effectiveness and  feasibility of in-situ biotransformation using  

molasses to treat groundwater contaminated with  chlorinated solvents.


Regulatory Requirements/Cleanup Goals:  Objective of study was to evaluate  enhanced in situ biotransformation as a remedy for  impacted groundwater. No cleanup goals were



Results: Data were provided for six downgradient monitoring wells   (three in the upper and three in the lower water-bearing zone) for   baseline samples that were collected in July 1999 prior to installing  the treatment system, and again in September 2000.


During this period, TCE concentrations appeared to  have been reduced more in the upper water-bearing  zone than in the lower water-bearing zone  

- In the upper zone, TCE concentrations were reduced from 4,110 to 323 µg/L and from 3,310  to 345 µg/L in two out of the three downgradient  monitoring wells. In the third monitoring well, TCE concentrations stayed approximately the same at 378 µg/L


- In the lower zone, TCE concentrations  were reduced from 2,770 to 2,300 µg/L in one out of  the three downgradient monitoring wells. In the > other two wells, TCE concentrations increased from 1,020 to 2,150 µg/L and from 3,170 to 4,450 µg/L


Cost Factors:


- The total cost for the pilot study was $306,557,  including $152,903 in capital costs, $72,560 in O&M costs, and $27,094 in other project costs such as reporting and project management  

- Unit cost was not calculated for this application

- No information was provided about the  projected cost for use of this technology at

full-scale at this site.


Description: The NWIRP in Dallas, TX is an active   plant that manufactures and assembles military and   commercial aircraft components and weapons systems.  Improper disposal of degreasers in these operations   resulted in contamination of the groundwater with  TCE and its daughter products. In October 1999, a   field demonstration of enhanced in situ biotransformation was initiated in an area near  Solid Waste Management Unit (SWMU) #15, which was an unlined acid neutralization pit that received liquid  wastes from site operations between 1970 and 1983.


The demonstration consisted of injecting   molasses solution into the upper and lower  

water-bearing zones using two injection wells, to  serve as a supplemental energy source for indigenous  microbes and enhance the existing microbial  processes occurring within the subsurface. After an 11 month period, sampling showed that TCE  concentrations appeared to have been reduced more in  the upper water-bearing zone than in the lower water-bearing zone. In the upper zone, TCE   concentrations were reduced by more than 85% in two out of the three downgradient monitoring wells,   while they stayed approximately the same in the   third well. In the lower zone, TCE concentrations  were reduced by approximately 15% in one out of the  three downgradient wells, and increased in the other  two wells. No information was provided about the   projected cost for use of this technology at   full-scale at this site. During the demonstration,   mold was found to be growing on the molasses   solution. As a result, the solution was prepared in  batches and automated injection was switched to   manual events followed by thorough cleaning of the  molasses mixing tanks.



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