HYDRO28189

• Permit No: M1980233
• IBM Index Class Name: Hydrology
• Doc Date: 4/8/1998
• Doc Name: COSTILLA LANDFILL PIT COSTILLA CNTY COLO
• From: GREYSTONE
• To: DMG
• Media Type: D
• Archive: No

Environmenml Planners, Scientists nnrl Engineers
April 6, 1998
Mr. James C. Stevens
State of Colorado
Division of Minerals and Geology
Department of Natural Resources
1313 Sherman Street, Room 215
Denver, Colorado 80203
RE: Costilla Landfill Pit, Costilla County, Colorado
Dear Mr. Stevens:
RECEIVED
APR 0 S 1998
Division of Minerals 8 Geology
.,.~ ~
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Greystone is submitting this letter on behalf of Costilla County to provide you with the data
collected during the quarterly groundwater monitoring and sampling site visit conducted on March
4, 1998 at the above referenced site.
A regional site map is provided as Figure 1. A site map displaying the location of the monitor
wells is provided as Figure 2. A groundwater elevation map is included as Figure 3.
Groundwater elevations were calculated using the measured groundwater elevation data and the
surveyed well casing elevations. The survey data and groundwater level measurements are
included in Table 1.
The groundwater gradient observed on March 4, 1998 ranged from 0.02 to 0.03 feet per foot
(ft/ft) to the southwest. Depth to water ranged from 35.77 ft below grade in well MW4 to 48.75
ft below grade in well MWS. Monitor well MW2 was not accessible.
A site map displaying the location of the monitor wells is included as Figure 2. Groundwater
samples were obtained from one monitor well (MWS). Monitor wells MWI, MW2, MW3 and
MW4 have been excluded from quarterly sampling and were not sampled.
The samples were analyzed for benzene, toluene, ethylbenzene, and xylenes (BTEX) using EPA
Method 602, and total dissolved solids (TDS) using EPA Method 160.1. Standards are presented
in Tables 4 and 5. The samples were also analyzed for Human Health Standards (total coliform,
barium, fluoride, lead, and nitrate+nitrite) and Secondary Drinking Water Standards (chloride,
iron, manganese, pH, and zinc) listed in the Colorado Department of Health, Water Quality
Control Commission, The Basic Standards for Ground Water. Standards are presented in Tables
2 and 3. In addition, all monitoring wells were measured for depth to water to determine the
groundwater gradient and flow direction.
5231 South Quebec Street • Greenwood Village, Colorado 801 I l
Phone [phone] • Fax [phone]
Web Site: www.greystone-consultants.com • E-mail: [e-mail]