Offsite Well Survey Report

This offsite well research was undertaken in an effort to identify potential off-base receptors, as well as better understand the nature of groundwater in the vicinity. Although the focus of the research was the �-mile radius of CSSA, significant groundwater users, including MUDs and large developments, were identified outside this �-mile boundary. Therefore, information on numerous additional key wells is included in this report. These key wells include:

Since these additional wells effectively double the size of the reporting population, only the wells within the original �-mile radius are fully documented in the appendices. The following general statistics regarding the well survey are provided in Table 3.1.

For ease of presentation, the remainder of the report will discuss 122 wells identified as key locations. The key wells are presented in Figure 3.1 and include 56 wells located somewhat outside the original �-mile survey area. A large-scale map that estimates the position of all 162 potential well locations is included as Appendix A. Additional data for those wells identified within the �-mile survey are included in Appendix B and Appendix C.

Category	Well Locations within CSSA¹	Well Locations within �-mile Survey Boundary	Key Well Locations included in this Report²	Potential Well Locations within 1-mile Survey Boundary³
Government-Owned Wells	21	24	29	30
Domestic Wells	-	23	45	65
Municipal, Irrigation, or Public consumption Wells	-	19	48	67
Total:	21	66	122	162
¹ This statistic includes 14 active/inactive CSSA well locations and 7 plugged and abandoned CSSA well locations. ² These statistics include those additional wells identified earlier in Section 3.1. This additional data is reflected on Table 3.3 and Table 3.4, as well as Figure 3.1. ³These statistics include those additional wells identified during the TPDES Permit Application by Banks Information Systems, and are presented in an appendix of that Application (Volume 6-2). Additional data regarding the Fairco Water Company system was obtained by CSSA, and are reflected in these statistics. Additional Fairco wells located significantly northwards in Kendall County were not considered for these statistics. Figure A-1 in Appendix A depicts the estimated positions of all 162 well locations.

Historically, as many as 139 wells (including both supply and monitoring wells) within the government installation boundaries of CSSA and Camp Bullis have been listed in Camp Bullis records. Of these, a total of 49 wells are confirmed as plugged and abandoned. Four wells at Camp Bullis are listed as either �unlocated� or with an unknown status. At this time, there are no unlocated wells at CSSA.

Category	Active/Inactive Water Wells	Plugged/Unlocated Water Wells	Monitoring Wells
Camp Stanley	12	7	2
Camp Bullis	25	46	47
Total:	37*	53	49
* This total may reflect a well that is listed both in the CSSA and Camp Bullis well inventory. While well CB-33 is located on Camp Bullis property, the well is also inventoried as CS-1 since it provides water to CSSA. A count of 36 active/inactive wells is likely to be more accurate.

As shown in Figure 3.2, only 24 of these key well locations are within the primary �-mile survey area. Another five Camp Bullis key well locations are thought to be within 1 mile of CSSA. Currently at Camp Bullis, a total of 45 environmental monitoring wells are in place for contaminant detection around four landfills, and two shallow wells are placed along Salado Creek. With exception of one Salado Creek monitoring point within 0.5 miles of CSSA, the remainder of the Camp Bullis monitoring wells range in distances between 6,300 to 25,000 feet from the CSSA boundary.

There are currently a total of 21 well locations at CSSA (Table 3.3). Some of the older wells are believed to date back to the early 1900�s. The current production well system was retrofitted and upgraded in 1996. With the exception of two locations (CS‑MW1 and CS-MW2), all wells were originally intended for public, stock, or agricultural use. Currently, only four wells (CS-1, CS-9, CS-10, and CS-11) are equipped for public supply distribution. Wells CS-9 and CS-10 supply the bulk of the facility water, which is supplemented by CS-1. Well CS-11 has been inactivated because of fecal coliform contamination. In addition, Wells CS-2, CS-3, CS-4, CS-16, and CS-D are no longer active because of their proximity to a known solvent plume that has locally contaminated the aquifer with solvent concentrations in excess of federally-mandated MCL concentrations. These wells now serve as detection monitoring points for the solvent plume in conjunction with monitoring wells CS-MW1 and CS-MW2. Wells CS‑G, CS‑H, and CS-I are located in the north pasture of CSSA, and are operated by the USDA as livestock wells. Well CS-H has suffered irreparable damage, and is no longer utilized. The public supply production wells draw upon the Middle Trinity aquifer, and all penetrate the Cow Creek Limestone. Seven abandoned wells (CS-A, CS-B, CS-C, CS-E, CS-F, CS-5, and CS-6) have been located and plugged.

While Camp Bullis maintains some limited records for 75 supply wells within its boundaries, only eight potential key well locations (not including one well duplicated as CS-1) were located within a 1-mile radius of CSSA (Table 3.3). Of these, only three were located within the �-mile survey. Camp Bullis reported that many of these wells cannot be located, have been eliminated by collapse and fill, or are significantly obstructed beyond usability. General research has shown that many wells listed at Camp Bullis were originally homestead or stock wells from ranching tracts that pre-date the establishment of Camp Bullis. Therefore, very little data regarding the completion of these wells are available from the public record. For the wells within the �-mile primary survey, no additional data regarding these wells were available. Under a separate contract, Parsons ES performed a separate report for Camp Bullis which stated that well CB-31 could not be located, and that CB-32 was obstructed and was recommended to be plugged. It is suspected that the well identified as CB-33 is the same as CSSA Well 1 (CS-1), and has been reflected as such in the maps. No data regarding CB-7 north of CSSA was available. It is unknown which formations Camp Bullis wells are completed within, but it is assumed that the wells primarily draw water from the Middle Trinity Aquifer. Within 1 mile of CSSA, the reported well completion depths ranged from 569 feet to 1158 feet MSL.

Wells that had available records indicate the main water source to be the Lower Glen Rose and Cow Creek intervals. The well depths at CSSA vary from 252 to 559 feet bgs in depth (between 734 feet and 974 feet MSL). All wells are completed with surface casing that ranges from 23 to 390 feet bgs. The production zones are completed as open boreholes that range from 6 to 10-inches in diameter. Submersible groundwater pumps are installed in both active and inactive supply wells, and range in depth from 430 to 528 feet bgs. Nearly 8 years of water level data show that the water table can fluctuate greatly, even by amounts as much as 200 feet. Currently, the typical water levels at CSSA range between 250 to 390 feet in depth bgs. Well tests in the 1990s at locations CS-1, CS-9, and CS-11 indicate that the Lower Glen Rose/Cow Creek intervals are capable of yielding approximately 75 gpm.

Past work to characterize the local geology in the central portion of CSSA at well CS-16 and the North Pasture has shown that the Lower Glen Rose extends to a depth of approximately 310 feet bgs (930 feet MSL). Approximately 70 feet of Bexar Shale to 380 feet bgs (860 feet MSL) and approximately 70 feet of Cow Creek Limestone to 450 feet bgs (790 feet MSL) underlie the Lower Glen Rose. Below the Cow Creek, the Hammett Shale is thought to act as a confining unit (Mace, 2000). At least two fault systems are known to cross CSSA, and are likely significant role players in the overall hydrologic regime beneath CSSA. Near the main entrance of the CSSA facility (Gate 2), the Bexar Shale/Cow Creek contact is nearly 60 feet lower in elevation (800 feet MSL) than in the central portion of the base and the North Pasture. Better understanding of the controlling factors of infiltration and movement of groundwater is relevant to the fuller understanding of groundwater properties. Important considerations include faulting and fracturing of geomedia, such as limestone. Additional studies by the U.S.G.S., including mapping of the geology and faulting at CSSA, are currently underway and will be incorporated in the Conceptual Site Model (CSM).

On October 5, 1999, representatives of CSSA and AFCEE met with Fairco Water Company engineers to discuss water supply. The information in this section is based upon minutes from that meeting and data provided by the Fairco Water Company (Appendix D).

The Fair Oaks Water System (Fairco) consists of 42 wells on the west and northwest side of Camp Stanley. Thirty-six of the wells feed the three water distribution plants that Fairco operates. Fairco has approximately 1,770 service connections and estimates that 2,500 connections will be serviced when development is complete. Only 33 of the Fairco wells are discussed in this report, and are listed on Table 3.4. These include supply wells FO-1 through FO-32, and FO-J1 (Figure 3.3). Most of the wells are for public use with the exception of wells FO-3 and FO-23, which are used for irrigation and well FO-5, which is listed as a domestic well. Three of the wells, FO-14, FO-20, and FO-24 are listed as unused, and well FO-20 is intended for water level observations only. All Fairco wells are open through the Lower Glen Rose and Cow Creek members. The irrigation wells are completed in the Sligo and Hosston units of the Travis Peak Formation which have water that is too mineralized for human consumption. Fairco performs a daily water level measurement on well FO-20, which is located across Ralph Fair Road from the Exxon service station. Weekly averaged levels of well FO-20 are used to determine the block rate cost of Fairco water. Fairco flow tests each well in the system on a weekly basis. Fairco is also in compliance with TNRCC water sampling requirements. Compliance sampling is based on those criteria established in SWDA and is administered by the State of Texas in 30 TAC �290, Subpart F. In general, SWDA requires the microbiological, radiological, organic, and inorganic analyses as primary constituents. Other secondary constituent levels are monitored for various inorganic compounds (e.g., natural water quality parameters). The frequency of sampling is based on prior detection of the analyte. Frequencies can vary from monthly to every three years for a specified non-detected analyte. Records indicate that Fairco pumped an average of 1.8 million gallons per day (mgpd) during August 1999 and 1.7 mgpd during September 1999.

Only seven of the Fair Oaks Water System wells are located within �-mile of the CSSA perimeter. Six of the seven within the �-mile boundary are public-use wells. The other well, FO-20, is used for water level observation only. Wells that had available records indicate the main water source to be the Lower Glen Rose and Cow Creek intervals. The well depths within the Fair Oaks water system vary from 319 to 1,067 feet bgs. Well completion depths within the Fairco water system range from 370 to 955 feet MSL. For the records available, surface casing is typically 8.625-inches in diameter within a 12-inch borehole. The production zones are completed as open boreholes with a typical diameter of 8 inches. Submersible groundwater pumps have been installed in all wells ranging in depth from 273 feet to over 962 feet bgs. The drilling reports indicate water levels that vary from 50 to 550 feet bgs, and capable of yielding between 5 to 195 gallons per minute (90 gpm average).

The Fair Oaks municipality has thoroughly documented their water well resources. Of particular interest is that the Fairco water supply has marked the top of the Cow Creek Limestone for all their wells. In the Fair Oaks vicinity, the top of the Cow Creek ranges in depth from 239 to 571 feet bgs, with an average depth of 421 feet bgs. The elevation for the Bexar Shale/Cow Creek contact ranges between 820 to 1038 feet MSL with an average formational contact elevation of 904 feet MSL. On average, the Cow Creek appears to be higher in elevation in the vicinity of Fair Oaks than what has been encountered at CSSA (800 feet to 860 feet MSL). This is due partially to structural features such as faulting and the overall southeast regional dip of the bedding planes. The average well elevation in Fair Oaks is 60 feet higher than those at CSSA.

The Jackson Woods Subdivision is located on the west side of CSSA and south of the Fair Oaks development. The subdivision is comprised of individual lots, many of which have personal domestic wells (Figure 3.4). Thirty-one wells have been identified in the subdivision and are listed in Table 3.4. The focus of this report is on the wells located within the �-mile boundary surrounding CSSA, which includes JW-1 through JW-14 in the Jackson Woods Subdivision. It is assumed that all wells are currently in use with the exception of well JW-2, which records indicate is unused.

Wells that had available records indicate the main water source to be the Lower Glen Rose and Cow Creek intervals. The well depths within the Jackson Woods vicinity vary from 360 to 600 feet bgs (720 feet to 898 feet MSL). For the records available, surface casing ranging in depth from 100 to 250 feet bgs has been installed in all wells within borehole diameters ranging from 6.625 to 8.75-inches. The production zones are completed as open boreholes with diameters ranging between 4.5 to 6.5-inches. Submersible groundwater pumps have been installed in all wells ranging in depth from 294 feet to over 460 feet bgs. The drilling reports indicate water levels that vary from 150 to 395 feet bgs, and capable of yielding between 10 to 70 gallons per minute (28 gpm average).

The Ralph Fair Road vicinity refers to 12 wells located on the west side of CSSA (Table 3.4). The wells follow Ralph Fair Road from the southern boundary of CSSA to the southern boundary of the Fair Oaks Development (Figure 3.5). All 12 of the Ralph Fair Road (RFR) wells are within �-mile of CSSA except one, RFR-5. Two of the wells are listed as public supply wells, RFR-1 and RFR-12. The remaining ten wells are assumed to be domestic-use wells. Nearly all of the wells were identified during the windshield survey. Information is available from the regulatory agencies for 50 percent of the wells in this area.

This geographic location has been established to identify and segregate wells located outside the southwestern corner of CSSA. These include municipal wells associated with Leon Springs Villa and Hidden Springs Estates, as well as domestic wells located along Curres Creek Road (Table 3.4 and Figure 3.6). Eleven wells have been identified by either regulatory agency document search or windshield survey. Ten of the identified wells are located within a �-mile of the CSSA perimeter. These include four wells in Leon Springs Villa (LS-1 through LS-4) listed as public use wells owned by Bexar Met Water District. Currently, well LS-3 is unused. A total of three domestic wells (LS-5, LS-6, and LS-7) are privately owned, and are assumed to be in active use. Five of these wells (LS-2, LS-3, LS-5, LS-6, and LS-7) are in extremely close proximity, and are all located within a radial distance of less than 300 feet. Bexar Met Water District also owns the four wells in Hidden Springs Estates. Two of the wells in Hidden Springs Estates, HS-1 and HS-3, are currently unused.

Wells that had available records indicate the main water source to be the Lower Glen Rose and Cow Creek intervals. The well depths within the Ralph Fair Road vicinity vary from 375 to 560 feet bgs (679 feet to 898 feet MSL). For the records available, surface casing ranging in depth from 30 to 373 feet bgs has been installed in all wells within borehole diameters normally 8.75-inches. The production zones are completed as open boreholes with diameters ranging between 6 to 6.5-inches. Two submersible groundwater pump depths were noted in the records, and are reported to be 336 feet and 504 feet bgs. The drilling reports indicate water levels that vary from 200 to 350 feet bgs, and capable of yielding between 10 to 28 gallons per minute (20 gpm average).

Well records indicate that all of the Leon Springs Villa supply wells are completed within the Cow Creek hydrostratigraphic unit, meaning the primary stratigraphic unit contributing groundwater to the well is the Cow Creek member. TWDB data indicate that completion information for LS-1 was not available. Water levels of approximately 270 feet bgs were reported in both LS-2 and LS-4 between 1967 and 1971. No other groundwater record is available.

No information regarding private wells LS-5, LS-6, and LS-7 was located. It assumed that these wells receive water from the Lower Glen Rose at a minimum. LS-7 is believed to have been installed during the early 1900�s, serving as a well for a Calvary stable.

The four municipal wells at Hidden Springs Estates range in depth from 880 to 925 feet bgs (405 feet to 460 feet MSL), and are completed in the Lower Glen Rose, Cow Creek, Hammett Shale, Sligo, and Hosston formational members. The boreholes are cased through the Upper Glen Rose with steel casing ranging depth from 410 to 420 feet bgs (917 feet to 928 feet MSL). Six-inch open boreholes have been completed into what is believed to be the Sligo and Hosston stratigraphic members (because of their depth), although the TWDB list the water-bearing units as the Cow Creek. Drilling logs do not indicate the presence of the Hammett Shale (or are not in sufficient detail). These wells reportedly yield up to 80 gallons per minute. Two wells (HS-1 and HS-3) are currently unused.

The Interstate Highway 10/Old Fredericksburg Road (I10/OFR) vicinity refers to a narrow corridor of businesses and homesteads that are located to the southwest of CSSA, and are all located at distances greater than �-mile from the facility (see Figure 3.7 and Table 3.4). This subset consists of six wells that are beyond the �-mile perimeter survey, but have been deemed relevant because of their proximity to CSSA. Because this research was not fully verified, the accuracy and reliability of this data should be considered as estimated. However, some locations were noted during the windshield survey (I10-1, I10-2, and OFR-1). It has been assumed that a well exists at the OFR-2 homestead, although a well was not directly observed.

Wells that had available records indicate the main water source to be the Lower Glen Rose and Cow Creek intervals. The well depths within the I10/OFR vicinity vary from 361 to 496 feet bgs (669 feet to 820 feet MSL). For the records available, surface casing ranging in depth from 80 to 267 feet bgs has been installed in all wells within borehole diameters normally greater than 8 inches. The production zones are completed as open boreholes with diameters ranging between 6 to 6.75-inches. Only one submersible groundwater pump depth was available from the record, reported to be 378 feet bgs. The drilling reports indicate water levels that vary from 138 to 250 feet bgs, and capable of yielding between 15 to 26 gallons per minute (22 gpm average).

	all of the Fairco Water Company wells south of Cibolo Creek;
	all wells located within the Jackson Woods community;
	all Bexar Met wells located within Leon Springs Villa and Hidden Springs Estates; and
	additional wells identified along Ralph Fair Road, Interstate 10, and Old Fredericksburg Road.