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TIM #4 Meeting Minutes
Treatability Study for Area of Concern 65
Camp Stanley Storage Activity
F41624-00-D-8024/Task Order 0058
Parsons 740999.02000

Date:  August 27 and August 28, 2002

Time:  1:00 P.M.-5:00 P.M. (8/27/02) and 9:00 A.M.-2:30 P.M. (8/28/02).

Place:  Camp Stanley Storage Activity (CSSA)

Subject:  TIM #4 to discuss regional geologic and hydrogeologic information from CSSA's environmental investigations with representatives of Camp Bullis as part of cooperative information exchange initiative; discuss format and content for the public meeting and the fact sheet, and review data quality objectivies (DQOs) for Area of Concern (AOC)-65 treatability study relative for future investigations.

Attendees:

^*Present on August 27, 2002 only   ^**Minutes prepared byGary Cobb, Parsons.

These meeting minutes are organized in the order discussed.

Regional Geologic/Hydrogeologic Information from CSSA Investigations

The meeting was opened with a presentation by Parsons describing the current understanding of the regional geologic and hydrogeologic conditions at CSSA.  Participants in this portion of the meeting included CSSA, Parsons, George Veni & Associates and representatives for Camp Bullis (UASCE, USAEC, Fort Sam Houston Office of the Staff of Judge Advocate [FSHOSJA], and Montgomery Watson). 

A summary of the geophysical testing completed in the vicinity of Building 90 was presented along an overview of the geologic information assembled from the associated study drilling activities.  Results of the AOC-65 geophysical surveys and drilling program suggest the presence of two fault zones trending northeast to southwest through the AOC 65/Building 90 area.  The northern-most fault is located north of Building 90 and is visible in the rock outcrop along the northern portion of the asphalt drive northwest of the Building.  The second fault zone is believed to trend through the area immediately south of Building 90 and is comprised by at least two faults.  The location of the second fault was based on results of the seismic survey and evaluations of geologic information from the area.  Based on geologic information, there is approximately 10 feet of offset across the northern fault and approximately 25 feet of offset across the southern faults.  An additional important feature identified in the drilling is that the number of fractures in the bedrock increases towards the southern fault zone.  The increase in the fracture density is expected to significantly influence the migration of groundwater and contaminants in the area.

Drilling activities completed around Building 90 for the installation of the SVE vapor monitoring points have identified subsurface features that would affect migration of groundwater and contaminants through the area.  In most of the borings drilled for installation of the vapor extraction wells/vapor monitoring points (VEWs/VMPs) and piezometers, a zone of highly weathered limestone was encountered at depths of 28 to 31 feet.  In several of the borings this zone included voids in the limestone rock material.  This zone is typically underlain by a competent limestone layer exhibiting little evidence of weathering.  Field data suggests that the competent limestone is relatively impermeable and that groundwater is moving laterally through the zone immediately above this layer, resulting in the significant weathering of this material.  This competent limestone layer creates a perched groundwater zone when water is infiltrating and moving through the shallow material.

A groundwater-bearing zone was identified at a depth of approximately 105 to 130 feet below land surface during the AOC-65 drilling activities.  This zone typically produces groundwater at approximately two to three gallons per minute during drilling operations.  This zone consists of vuggy yellow fossiliferous limestone and appears to be laterally continuous across the AOC-65 area.  This zone is generally considered the upper-most productive zone and typically contains water following heavy rainfall events and during periods of higher groundwater elevations.

The current conceptual model for groundwater flow at AOC-65 involves infiltration and lateral flow through the shallow weathered zones, primarily through the highly weathered zone present between the depths of 28 and 31 feet.  Groundwater in this zone is in effect "perched" upon the underlying low permeability competent limestone layer.  Groundwater flows laterally through this weathered zone with an anticipated flow direction towards the south.  As the shallow groundwater moves laterally, it encounters the fracture and fault network associated with the local fault zones.  Upon encountering the fracture/fault network, groundwater begins to migrate vertically along these features and also migrates laterally from these fractures and faults into unsaturated portions of the bedrock material.  Groundwater continues to migrate laterally and vertically through bedrock material until it enters the static saturated groundwater regime.

On a regional scale, the results obtained at AOC-65 appear to be consistent with observations across the post.  Investigations activities conducted during the post-wide groundwater investigation study have focused on characterizing groundwater conditions through the Bexar Shale and Cow Creek formations. 

The Upper Glen Rose Formation is present over much of the post and, where present ranges in thickness from a few feet to over 100 feet.  The contact between the Upper Glen Rose and the Lower Glen Rose is distinguished by the presence of a corbula bed at the base of the Upper Glen Rose Formation.  Recent correlations by Parsons from borehole data indicates that the corbula bed is present just beneath the highly-weathered zone encountered at a depth of approximately 30 feet in the Building 90 area.  Mr. Veni added that the reason for the high degree of weathering observed in this zone is due to the presence of gypsum, which is rather easily dissolved from the formation by groundwater.

Regionally, groundwater elevations in the Lower Glen Rose can fluctuate from approximately 60 feet below ground surface following significant precipitation events, to over 200 feet below ground surface during periods of drought.  A rapid rise in groundwater elevations is typically observed following rainfall events due to high infiltration rates resulting from the highly fractured and weathered nature of the bedrock material.  The direction of groundwater flow is typically to the southwest, but exhibits some localized variability as groundwater levels fluctuate in response to rainfall events. 

Groundwater flow in the Lower Glen Rose appears to be highly variable across the post and is controlled by the presence of fractures, dissolution features and zones of high permeability.  A groundwater productive zone approximately 60 feet thick is typically encountered in the Lower Glen Rose Formation just immediately above the Bexar Shale and appears to be continuous across the base.  Water level data suggests that the Bexar Shale is a confining unit for the underlying Cow Creek Formation.  Following rainfall events, a delayed rise in the water levels in the Bexar Shale and the Cow Creek is observed, suggesting a weak hydraulic connection between the these layers and the overlying Lower Glen Rose.

Contaminant concentrations from borehole packer tests an increase with depth through the saturated portion of Lower Glen Rose down to the lower productive zone.  Contaminant concentrations in the lower productive zone are below detction limits or significantly lower than in the upper layers.  The lower concentrations in the productive zone are believed attributable to dilution with the increase in permeability of the aquifer material.

     Public Meeting and Fact Sheet Format and Content

On August 28, 2002, CSSA and Parsons met to discuss the public meeting and fact sheet for TO 0058.  A draft of the fact sheet (Fact Sheet No. 10) prepared by Parsons under TO 0058 was presented to CSSA for review.  CSSA commented on the draft fact sheet and Parsons agreed to make the suggested changes and re-submit the fact sheet to CSSA for additional review.

Plans for the static displays for the upcoming public meeting were discussed.  Suggested topics for the displays were: Mission; History and Previous Investigations; SWMU B-3 Cleanup; AOC-65 Cleanup; and, Groundwater Investigation.  Review of the posters prepared for the 2001 public meeting indicated that the posters for the Mission display may be re-used for this public meeting, whereas new posters must be prepared for the remaining displays.  Parsons will prepare drafts of the posters and forward to CSSA for review.  The draft posters will be finalized ahead of the Risk Communication training scheduled for September 23 and 24, 2002.  In addition, CSSA currently owns four displays, so Parsons will need to rent two displays for the public meeting.

Review of DQOs for Future Investigation and Treatability Activities

    CSSA and Parsons discussed the TO 0058 data quality objectives for agreement with future TO 0058 activities.  Based on the activities currently planned under TO 0058, the DQOs are believed to adequately address the planned activities.  One issue was raised regarding the potential plan to install heat-pulse flowmeters to assess rate and direction of groundwater flow at specific locations and depth intervals at the base.  CSSA expressed a desire to continue with an evaluation of the cost and feasibility of installing the flowmeters.  However, since the installation of these flowmeters would require drilling, this task may be completed under TO 0042 because the TO 0058 drilling activities were almost complete.  Modification to either the TO 0058 or TO 0042 DQOs may be warranted if CSSA proceeded with the installation of the flowmeters.

Action items

Agenda for Technical Interchange/Progress Meeting #4