DSHW-1990-002481 - 0901a06880156975

Norman H. Bangertpr
(iov»'rnor
Suzanne Dandoy, M.D.. M.P.H.
ExoruUve iJin-' tnr
Kenneth L. Alkema
lHT^^^•U)^
FPU.
DEPARTMENT OF HEALTH
DIVISION OF ENVIRONMENTAL HEALTH
Bureau of Solid & Hazardous Wasie
288 North 1460 West. P O. Box 15690
Salt Lake City. Utati 84116-0690
1801)538-6170
^K^ •? n
DSHW TN
1990-20811
E. Richard Anderson, Manager
Environmental Planning and Operations
Hercules Aerospace Company
Bacchus Works
Magna, Utah 84044-0098
Dear Mr. Anderson:
My staff has reviewed the information submitted on the "Contaminant Transport Modeling
of a Chlorinated Solvent Plume East Nirop Area", "East Nirop Ground Water Modeling"
and "Work Plan for Drilling of Additional Monitoring Wells in East Nirop Vicinity". The
following coirmients and questions v^ll require a vmtten response by April 15, 1990:
1. Hercules should consider collecting VOA samples from Piezometer P.3 prior to
drilling the on-site deep well. If P.3 can be purged and a sample collected,
valuable information could be generated concerning VOA contamination in the
deeper portion of the aquifer.
2. Extreme care v^ll need to be taken in drilling GW-73 to ensure that contamination
is not spread to possible clean zones within the aquifer.
3. The information used for the large grid for the ground water models north of the
NIROP property boundary is questionable. The majority of off-site wells are
installed at a considerably deeper depth than the Hercules wells. The off-site wells
could be located in a different aquifer. The wells could be under a confined or
partly confined condition. Because the off-site control is so poor, ground water
flow and contaminant transport could be considerably different than the models
predicted.
4. The proposed location of the off-site wells might not intercept the plume as
predicted and additional wells could be required to delineate the plume.
5. Hercules should consider implementing a source remediation program as soon as
possible to prevent further contamination from migration off-site.
If you have any questions concerning this letter, please contact Don Verbica or Rick Page
at 538-6170.
Sincerely,
)eimis R. Downs'
Executive Secretary
Utah Solid and Hazardous Wastes Committee
Harry Gibbons, M.D., M.P.H., SLCCHD
DRD/DGV/cw