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Addendum to Sampling and Analysis Plan Specific to Delivery Order DO23
Section 1 - Introduction and Field Operations
1.1 - Field Operations
No changes made.
1.1.1 Site Reconnaissance, Preparation, and Restoration Procedures
No changes made.
1.1.2 Surface Geophysical Surveys
No changes made.
1.1.2.1 Determination of Electromagnetic Measurement Locations
No changes made.
1.1.2.2 Equipment Functional Checks
No changes made.
1.1.2.3 Instrument Calibration
No changes made.
1.1.3 Soil Gas Survey Methods
No changes made.
1.1.3.1 Determination of Soil Gas Sampling Locations and Sample Depth
No changes made.
1.1.3.2 Soil Gas Sampling Method
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1.1.3.3 Soil Gas Sample Screening
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1.1.3.4 Soil Gas Analytical Equipment
No changes made.
1.1.3.5 Target Compounds and Calibration
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1.1.4 Borehole Drilling and Soil Sampling
No changes made.
1.1.5 Field Screening During Drilling and Sampling
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1.1.6 Lithologic Descriptions
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1.2 - Well Construction and Development
1.2.1 Monitoring Well Construction
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1.2.1.1 Monitoring Well Completion Form
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1.2.1.2 Monitoring Well Surface Completions
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1.2.2 Monitoring Well Development
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1.2.3 Monitoring Well Purging
No changes made.
1.2.4 Deep Monitoring Well Construction and Development
The installation, development, and purging of the new monitoring wells will follow the procedures specified for deep monitoring wells in Section 4.4 of the Work Plan for the Lower Glen Rose Monitoring Well Installation with the following exceptions.
Temporary casing will not be installed. It has been established that perched water is not present.
Pilot holes will not be drilled. Information of the depth to the Bexar Shale is sufficient to complete the well without a pilot hole.
Wells will be logged at each change of lithology, not at 0.5 foot intervals.
The wells will not be geophysically logged.
No wells will be cored through the saturated zone.
1.3 - Borehole Abandonment Procedures
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1.4 - Surveying
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1.5 - Equipment Decontamination
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1.6 - Field Activities
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1.7 - Investigation-Derived Waste Handling
No changes made.
1.8 - Upgrade of Existing Wells
Water wells 1 and 11 are scheduled for upgrades as part of the groundwater monitoring program. During all well upgrades, the pump, pump piping, and pump wiring will be removed from the well. Wells 1 and 11 will be treated with carbon dioxide in an effort to increase the transmissivity of the formation in the area immediately around the borehole to allow improved water production.
Pump, piping, and wiring will be removed by a subcontractor prior to well treatment. Well 11 is housed in a prefabricated building and will require removal of the roof in order to pull the piping. Well 1 is housed in a cinderblock structure and may also require roof removal. All tasks required to gain access to the wells for piping removal will be carried out by the subcontractor responsible for pipe, pump, and wiring removal.
After the pump and pump piping have been removed a subcontractor will perform the carbon dioxide treatment in both wells. The carbon dioxide (CO2) treatment is a three step process in which a packer is placed in position to isolate the desired production zone, liquid CO2 is injected, and the well is redeveloped and tested. The injected CO2 penetrates the surrounding aquifer through pre-existing flow pathways. Expansion, the formation of carbonic acid, and the freezing of the water after injection act to remove chemical and biologic encrustations. The treatment process may be repeated several times to ensure that the well is revitalized to its fullest potential. After treatment, the wells will be redeveloped by the above subcontractor using air lift operations as described in Section 1.2.2 of the Field Sampling Plan.
The pump, pump piping, wiring, and pumphouse roofs will then be reinstalled by the subcontractor responsible for their removal. If the existing piping and wiring is observed to be in disrepair after removal from wells 1 and 11 the subcontractor will replace these items with those specified by CSSA.