Subject:

TIM #2 to discuss additional electrical resistivity results, plan future geophysical testing, and discuss comments on draft work plans prepared for TO 0058.

Subslab ventilation vs. SVE treatability study system – Parsons described the different objectives and construction details of the two SVE systems, and explained that the use of subslab ventilation system wells are limited in the plans because they will not be screened in the underlying rock (only in the fill material underlying Building 90) and their main function is to monitor contaminant levels in the fill material and provide a mechanism for contaminant removal.

VEP – Refers to possible application of vacuum enhanced pumping technology that is a dual phase (liquid and soil gas) extraction system.  The VEP system is currently not planned for testing as part of the SVE treatability study, but, if possible, the SVE system will be constructed such that a VEP pilot test system could be plumbed to the SVE system if testing is desired in the future.

Deletion of DQOs from the Work Plan – CSSA deleted the DQOs from the work plan appendix, but not from Section 1 of the Environmental Cleanup Plan.  The reason for the deletion is that CSSA and AFCEE have modified the format for DQOs (and provided a copy of the draft DQOs for the groundwater investigation at CSSA), and that a new set of DQOs will need to be prepared for TO 0058.  CSSA did not wish to include the DQOs in the plan appendices, but reaffirmed the need to develop DQOs for the task order.  The DQOs will need to provide rationale and justification for all of the data collection activities that are planned.  Also included will be the reasoning for extraction well, vapor monitoring point, subslab ventilation, and piezometer locations.

CSSA requested inclusion of recommendations in the Environmental Cleanup Plan.  Parsons explained that the purpose of the Environmental Cleanup plan is to serve as the basic work plan for the task order, as it includes all activities planned including the removal action, the SVE treatability study, and the groundwater recharge study.  Recommendations are usually developed in the data evaluation and reporting stage, although other possible data needs and recommendations will be added to the treatability test work plan that was prepared as a companion document to the Environmental Cleanup Plan.  As such, CSSA agreed that no recommendations would be included in the Environmental Cleanup Plan.

CSSA commented on the northerly trending potentiometric gradient for groundwater in the three Lower Glen Rose Wells sampled in September 2001.  Parsons purposely did not expand on the implications of this phenomenon in the plans because only one round of data was available on the apparent hydraulic gradient, but wanted to mention it because its implications could be significant if future data verifies the gradient direction.   The gradient suggests that flow in the uppermost aquifer formation is to the north, whereas the contamination has been detected to the west and southwest of Building 90, not to the north.  Also of interest is the likely presence of at least one, and maybe multiple fault lines located in the vicinity of Building 90.  The hydraulic gradient data provides additional information on the contaminant migration pathway, but much more data needs to be collected before Parsons would feel comfortable drawing conclusions.  At this time, Parsons prefers to use the information, coupled with the geophysical test data, to develop conceptual theories regarding the local groundwater and contaminant migration pathways to help guide future data collection efforts designed to verify or disprove those theories.  CSSA agreed to limit the discussion of the northerly hydraulic gradient, but wanted Parsons to include the continued collection of data as part of the DQO to identify the primary and secondary contaminant migration pathways.

Parsons used the terms “strong” and “weak” to describe geophysical anomalies.  Gary Cobb explained that these terms were used to differentiate the conductive anomalies that appeared (shape, size, depth, orientation, and location of signatures) in parallel test lines.  The strong and weak terms were used to refer to the relative electrical conductivity of the anomalies. Parsons will revise the test work plan discussion of geophysical testing results to clarify the use of these terms.

CSSA questioned whether there were any other VLF sources located closer to Texas than the one used during Parsons brief attempt to use VLF at CSSA.  Gary Cobb indicated that there are only three sources in the United States, and only one source produced a signal of sufficient strength to be useful at the site.

CSSA questioned whether the piezometer design was mandatory, or whether a design, such as the Westbay multi-port sampler could be used.  Parsons explained that the Westbay would not enable servicing of transducers or water level measurement devices.

CSSA wanted a better explanation of why the SVE/peizometer locations were selected.  CSSA indicated that the selection of locations should be described in DQO format, and summarized in test work plan.  Parsons agreed to include an explanation in the DQOs developed for TO 0058.

CSSA wanted Parsons to explain the procedure for construction of piezometers to depths of 100 feet or greater below grade.  Parsons indicated that the work plan specified no construction if groundwater levels were above 150 feet below grade because that was the approach that was discussed during previous meetings.  CSSA indicated that they preferred that the piezometers be installed regardless of the water levels, and that we should employ the same methodology used for installation of monitoring wells under different delivery orders.

The surface completions for piezometers were discussed.  The figures presented in the draft plan had already been revised, and Kyle Caskey had some additional ideas on how to improve the design near the surface.  A new piezometer design will be developed for inclusion into the final treatabilty test work plans based on the discussion.  The primary concerns were installing the surface completion to provide access for servicing the down-hole monitors, collection of groundwater samples (with miniature bailers), and elimination of water infiltration into the piezometer manhole.

CSSA requested that Parsons consider use of personal air monitoring devices during work inside Building 90 to provide data that verifies that the air quality inside the building was not impacted by the work activities (drilling, soil gas testing, etc.).  Parsons will include the use of personal air samplers and/or monitoring stations in the health and safety plan for the response actions in and around Building 90.

Under the topic of operations and maintenance, the management of knock-out pot moisture was discussed.  Placement of the blower housing was a critical aspect affecting management of the accumulated moisture. Since placement on the dock could cause some noise, exposure to weather, or dock access issues, it was initially decided to place the blower housing on the ground surface.  However, placement on the ground surface away from the dock would make it more difficult to manage the knock-out pot water.  From our findings at SWMU B-3 SVE, the water in the knock-out pot is expected to contain relatively high levels of volatile organic contaminants, and would require temporary containment, transport to the GAC treatment unit, and treatment.  It was tentatively decided that Parsons would make preliminary designs for the blower housing to be situated on the dock, and will try to include measures in the design to minimize impact from noise or damage from weather.

CSSA wanted Parsons to explain why the test plan only included one round of testing for natural attenuation parameters.  The plan calls for one round of groundwater sampling for natural attenuation parameters and baseline VOCs prior to initiating any SVE from all VEWs, piezometers, and nearby monitoring wells.  An additional round may be warranted, but given the period of performance of the project (anticipated 18 additional months), it may not be technically prudent.  Generally, at least one year is recommended for collection of natural attenuation parameters.  Based on the results from the initial testing, it may not be necessary to collect any data other than VOC concentrations from groundwater at the site.  PES will provide recommendation for additional NAP analyses as needed.

CSSA indicated that Parsons should prepare an Operations and Monitoring (O&M) summary report quarterly or semi-annually to document the O&M parameters.  Parsons explained that an O&M plan would be prepared at the conclusion of the SVE treatability testing to identify the types of data that should be collected during O&M visits and system checks through the period of performance of this task order.  Pertinent information will be included in the final Treatability Test and Technology Evaluation Report tentatively due approximately one year after completing the SVE treatability testing.  A quarterly or semi-annual update (short memorandum with summary of collected data) would be included as a requirement in the O&M and reporting sections of the work plans. 

Parson will prepare an agenda for the meeting with regulators on March 5, 2002, and will prepare presentation material, in draft format, for the meeting.

Parsons will digitize the drawings CSSA provided on Building 90 (upon award of additional funding).

Parsons will continue to research data collection tools for water levels in wells, telemetry, etc.

Parsons will begin revising the draft Environmental Cleanup Plan and the draft Treatability Study Test Plan for final submittal to regulators and inclusion into the Environmental Encyclopedia.

Parsons will evaluate the use of a pipe camera in the discharge lines under Building 90 to determine whether there are any indications of leaks, and to track the location of the discharge lines under the building to provide additional information to the soil gas data for selecting more appropriate locations for subslab ventilation wells and soil borings by focusing on portions of the pipe where ruptures may be present.  The pipe is reportedly a clay pipe at least six inches in diameter.

Parsons will prepare a short recommendation for future geophysical testing, and will include a proposed schedule and figure depicting locations for test locations.

Parsons will prepare specific Data Quality Objectives for the TO 58 tasks using the newly revised format developed by CSSA.  Following review and approval by CSSA, these DQOs will be incorporated into the Environmental Cleanup Plan.