Texas Low-Level Radioactive Waste Disposal Authority

Lawrence R. Jacobi, Jr. General Manager

7703 North Lamar Blvd. Suite 300 Austin, Texas 78752 (512) 451-5292

Members of the Board: John E. Simek, C.H.P., Chairman Elbert B Whorton, Ph.D., Vice Chairman Jim R. Phillips, Secretary James P. Allison Milton J. Guiberteau, M. D. William L. Fisher, Ph.D.

MEMORANDUM TO: Ruben Alvarado, P.E.
FROM: Lawrence R. Jacobi, Jr., P.E
DATE: July 29, 1987
SUBJECT: Evaluation of Andrews County Site

Based on the attached report, I don't see any reason to continue our evaluation of the proposed site area in Andrews County. Unless we can prove absolutely that the Ogallala is not recharged from or discharged to the site area, we are precluded by TEX. REV. CIV. STAT. ANN., art 4590f-1, Sec. 6(a)(7)(B) from considering this area as a suitable site.

If the County Commissionerts Court, or the County Industrial Development Group want to conduct further evaluations to answer the questions posed on page 3, we should have our own geologist available to oversee the work. If they are not willing to underwrite the work, then we should notify all interested parties that we have no further interest in the site.

LRJ/rwd

cc:
B. Clayton
W. Fisher
S. Hartman
C. Kreitler
==================ATTACHED==================

BUREAU OF ECONOMIC GEOLOGY
THE UNIVERSITY OF TEXAS AT AUSTIN
University Station, Box X
Austin, Tx 78713-7508
(512)471-l534 or 471-7721

July 24, 1987

Mr. Rick Jacobi, General Manager
Texas Low-Level Radioactive Waste Disposal Authority
7703 North Lamar Boulevard Suite 300
Austin, Texas 78752

Dear Rick:
Attached are my comments on the geology and hydrology of the potential site on University of Texas Block 12 in Andrews County, Texas. Please give me a call lf you need further information.

Sincerely,
[signed]
Charles W. Kreitler
Program Director for Environmental Studies

CK:mc Enclosure

[stamped recieved: Jul 28 1987 Texas Radioactive Waste Authority]

==================ATTACHED==================
Review of Geology and Hydrology of the northwest corner of University of Texas Lands Block 12 in Andrews County, Texas, as a possible site for a Low-Level Nuclear Waste Disposal Facility

Charles W. Kreitler

Methods- The site region was visited by Ruben Alverado, Tom Blackburn (Texas Low-Level Radioactive Waste Authority) and Charles Kreitler (Texas Bureau of Economic Geology) on July 22, 1987. We flew over the site region, then returned to the site region by car for approximately 1 hour. We inspected a borrow pit which had a depth of approximately 25'. The specific site was not visited, but geology of those areas which we did see were close to the site and considered to be representative of site conditions.

Geology- The geologic section is as follows. There is a thin cover sand which forms deflation pits or sand dunes. A thin clay-rich soil zone is beneath the sand. A 5-10' punky caliche underlies the soil. Beneath the soil is poorly comented sands. These observations are based on examination of a borrow pit on Block 12. The Ogallala Formation is the next unit encountered and is estimated at approximately 100 feet thick or less in the general area. There may be a topographic high of the underlying Dockum that causes a thinning of the Ogallala Formation. Depth to Dockum may be as shallow as ~55'. Darrell Jackson, a geologist from Andrew County, suggested that a thick Dockum redbed section should then be found. At approximately 1000' Santa Rose sands of Lower Dockum should be encountered. Cretaceous strata are mapped in the salt lake deposits and may be present in the site area.

Hydrology- Two aquifers need to be considered as well as possible mechanisms of recharge and discharge for the area. The two aquifers are the Ogallala and the Santa Rosa sands. Both aquifers are produced and used for domestlc and stock purposes. The Ogallala ia used for municipal supply in the area. The Dockom is also used for oil field operations. The Ogallala aquifer in Andrews County is along the southern extent of the major High Plains aqulfer. Saturated thickness is thin and may be less than 20' (Knowles and others, 1984). Small windmills were observed on Block 12 which should have been producing from the Ogallala. Local geologists argued that there is not any water at their recommended location because of the topographic high of Dockum underlying the Ogallala. There is Dockum production in the area. The potentiometric surface should be a couple hundred feet below land surface. Total Dissolved Solids should be approximately 3000 ppm (Dutton and Simpkins, 1986). Large windmills that supply water for domestic and stock use were observed on Block 12. Cretaceous ground water may also underlie the region. Hydrologically we don't know its importance in the region. Land surface surface is very flat. Soil texture is very sandy. Precipitation is about 16" per year. Heavy rainfalls should soak into the ground and not run off. Dune fields at the recommended location should enhance recharge. Well developed vegetation occurs over much of the area. Shin oaks cover most of the area. A local geologist referred to the heavy density of oak as the worlds largest oak forest, also the shortest. This woody, deciduous plant suggests that the amounts of precipitation are higher than seen in arid environments or at least moisture is trapped in the soils for better utilization by deep tap roots. Dr. Ronit Nativ of the Bureau of Economic Geology previously has sampled the water from the Andrews City wells and found tritium, indicating active recharge to the Ogallala in this region. We may have observed a sink hole during our flight over the University land. There was a small pond with a road that appeared "to go through the pond," but was now detoured around it. Salt solution and collapse may be occurring in the region. It may also be just a dug tank.

Considerations of this site for a low-level radioactive waste disposal facility- Important criteria for containing waste ln a low-level radloactlve waste disposal facllity are low annual rainfall, a thick unsaturated section, impermeable rocks beneath the site and no potable ground water supply beneath the site and simple geology. A review of the information indicates that this site is marginal. Rainfall at the site supports grass land to shin oak forest vegetation, indicating higher precipitation than we have seen further to the west. Precipitation in Hudspeth County is 1/2 of rainfall in Andrews County. The very flat terrain and sandy nature of the soil enhances recharge From precipitation. Windmills producing from the Ogllala are found in close vicinity to the site, suggesting that there is shallow ground water beneath the site. Tritium in the regional Ogallala ground water indicates active recharge in the area. The salt lakes that are close to the site probably are discharge points for Ogallala waters in the region, indicating an active hydrologic system. This ground water may not constitute an important water supply, but it may provides an important mechanism for, waste transport. If there is a thin saturated section within the Ogallala, it precludes any benefit of thick Dockum redbed shales. If the depth to impermeable bedrock is 50' or more excavation costs to those depths may be prohibitive. The ground water in the underlying Santa Rosa sands of the Dockum should be considered as a potable water supply in that it is being used locally for domestic and stock usage as well as for oil field operations. Further consideration of this site requires additional data collected on site to determine how shallow the Dockum is and whether there is ground water in the Ogallala.

Recommendations for future work- If the Texas Low Level Radioactive Waste Authority is interested in pursuing this site more data is needed at both the site specific and regional basis. The following information is needed at the site:

1. Thickness of the Ogallala at the site. Is the thickness of the Ogallala too great for the construction of disposal trenches?
2. Is there ground water in the Ogallala beneath the site? What is the thickness of the saturated section in the Ogallala? If there is water present, what is its chemical composition and does it contain tritium?
3. Is there any Cretaceous strata beneath the site?
4. How much shale is beneath the Ogallala? Does it represent an effective barrier to potential migration to possible deeper potable waters in the Santa Rosa sands?
5. Are there abandoned well bores within the site area? Considering the extent of oil activity in the region, there may be some drilled and abandoned wells in the site area.

Ogallala investigations at the site can be accomplished by drilling 3 to 6 holes with an air rig to the base of the Ogallala. Cuttings should be collected. The holes should be located so as to evaluate the geometry of the suspected Dockum high. These wells should be cased with slotted pipe to determine if there is a static water table in the Ogallala at the site. At this point, drilling on the site to determine the thickness of the Dockum shales is prosbably not required. Regional assessment of previously logged holes should provide a reasonable estimate of shale thickness that could be expected at the site.