C153349 Feasibility Study

• Contract/PO #: C153349
• Contractor Name: Brook Forest Water District
• Contract Type: Loan
• Water District: 9
• County: Jefferson
• Bill Number: SB 80-67
• Loan Projects - Doc Type: Feasibility Study

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C. Geology

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A geologic report for the Brook Forest Water District service area was

prepared by Willard Owens Associate6, Inc. in November 1977. The report

describes the geological setting of the district and locates apparent fracture

zones in the underlying bedrock. potential well sites were recommended where

it appeared that intercepted fractures would yield the most water. The infor-

mation contained in the report was ~sed to provide the following general

geological description of the area,

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The district is underlain by Precambrian metamorphic and igneaous rock

consisting primarily of granitic gneiss and micaceous schist. The bedrock of

the area is weathered but has occasional zones of more resistant granitic gneiss.

The central or eastern part of the district is underlain mostly by gneiss and

schist, which is well foliated and moderately fractured in some areas. Most

of the fractures are steeply dipping or vertical. However, some fractures

occur as general planes which parallel the foliation of the gneiss.

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Within Brook Forest Filings 1 and 2 (see Figure-3,PageI5) the foliation has a

strike. from the northwest to the southeast with a dip toward the northeast.

These filings are underlain by mostly massive gneiss with apparent facture

zones within the exposed coarse-grained granite which trend northwest to south-

east. Filings 4 and 5 are underlain by massive medium-grained Silver Plume

granite with little fracturing. Fracturing is widely spaced and the fractures

do not extend to considerable depth.

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The majority of the deep fracture zones occur 1n the eastern part of the

district. Well sites along these fractured zones have the best potential for

producing dependable water supplies. This fact appears to be supported by

the yields of existing district wells. The two wells located in the eastern

part of the district produce significantly greater quantities of water than

the two wells in the western part.

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