2002-07-26_PERMIT FILE - M2002052 ‎(5)‎

• Permit No: M2002052
• IBM Index Class Name: Permit File
• Doc Date: 7/26/2002
• Doc Name: RESPONSE TO ADEQUACY REVIEW COMMENTS 112 CONSTRUCTION MATERIALS APPLICATION WESTERN EQUIPMENT
• From: APPLEGATE GROUP INC
• To: DMG
• Media Type: D
• Archive: No

Alluvial Aquifer Characterization
Water levels were observed dwing drilling of the exploration holes and again 24 hows after
drilling (Terracon, 2002). All nine (9) bore-holes were completed through the entae alluvium to
bedrock. Water level measwements aze summarized in Table 1. The water levels were used to
construct a preliminary water table contow map. The contow map is considered preliminary
since only one water level measwing event was conducted. Using the available data, the
groundwater gradient is estimated to be on the order of 0.005 (0.5 feet decline per 100 feet of
horizontal distance) from northwest to southeast across the site. However, at the eastern edge of
the site, neaz the confluence of the Big Thompson and Little Thompson rivers, groundwater
gradients become less defmable.
Table 1
Summary of Water Level Measurements
Bore Hole
Number Depth to
Water ft Depth to
Bedrock ft Saturated
Thickness ft Approximate
W.L. Elevation
T-1 5.5 35 29.5 4728.5
T-2 6.5 32 25.5 4724.0
T-3 7.5 31 23.5 4721.5
T-4 7.0 35 28.0 4722.0
T-5 2.5 25 22.5 4728.0
T-6 5.5 27 21.5 4723.5
T-7 7.0 30 23.0 4721.0
T-8 5.5 16 10.5 4724.5
T-9 5.0 17 12.0 4723.0
AVG 5.8 28 21.8 - - -
Water level measurements made 24 hoius after bore hole com lesion.
Several factors likely influence the groundwater surface of the alluvial aquifer across the site.
The site is confined at the east and northeast boundaries by the Big Thompson River and at the
southeast boundary by the Little Thompson River. In addition, several groundwater lakes are
currently present on-site. During the growing season, fields west and northwest of the site aze
irrigated throughout the season.
The saturated thickness of the alluvial aquifer varies across the site from 10.5 to 29.5 feet,
averaging approximately 22 feet. For the alluvial material in the saturated thickness, published
estimates ofporosity for sand (and sand and gravel) deposits range from 20 to 30 percent.
The grain-size distributions for the alluvial samples were used to estimate the bulk hydraulic
conductivity for the aquifer. The hydraulic conductivity was estimated using two different
methods: the Prugh Method (Powers, 1992) and the Hazen Method (Fetter, 1994). The Prugh
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