REPORT
OF GEOLOGIC/HYDROGEOLOGIC SERVICES
LYNNWOOD
ESTATES WATER SYSTEM
KOOTENAI
COUNTY, IDAHO
INTRODUCTION
This report
summarizes the result of the geologic/hydrogeologic services for the
Lynnwood Estates Water System (LEWS).
The services are provided by the Idaho Water Resources Research
Institute’s (IWRRI) Technical Assistance for Rural Ground Water
Development Within Idaho program.
The LEWS is
located approximately one to two miles northeast of Athol Idaho in
Kootenai County. LEWS
supplies about 20 connections from Well #1 and Well #2 that are located
in Figure 1. Water well reports for Wells #1 & 2 (Figures 2 and 3)
show approximate production rates at the time of drilling of 50 gallons
per minute (gpm) for both wells. According
to the water system operator for the LEWS Well #1 has been producing
silt and sand with the pumped water.
The turbid water is undesirable for the water users and can
create the potential for damage to the pump and in-line meters. LEWS has
requested assistance in evaluating the potential to reduce or eliminate
the turbid water by remediatingWell#1 or replacing the production
capacity with a new well. This report was written to address the general issues and
options regarding Well #1. It
may be necessary to perform additional studies to further evaluate the
conclusions of this memorandum.
The geology
within the vicinity of Athol is part of a larger geologic setting
defined as the Rathdrum Prairie. The geology in the area of Athol consists predominantly of
glacial deposits or reworked glacial deposits that filled in a
pre-existing bedrock channel and or depressions. The bedrock is composed
chiefly of Precambrian metamorphosed sedimentary deposits that were
later intruded by Cretaceous granitic rocks.
WELL
#1 CONSTRUCTION
Well # 1 was
completed. on February 6, 1991 with an 8-inch diameter steel casing to a
depth of 400 feet bgs within a mixture of clay, sand and gravel. The
static water level measured at the time of drilling was 305 feet bgs.
The casing was then perforated from 360 to 400 feet bgs with additional
perforations using a Mills Knife along the same length of casing. The
pump was set at 357 feet bgs just above the perforated section.
The silt and
sand that is being pumped from the well is most likely being introduced
from the “clay” and “sand” adjacent to the perforated openings.
RECOMMENDATIONS
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