Tamarack Modeling Project Documentation

• Description: Tamarack Modeling Project Documentation - DRAFT
• State: CO
• State: NE
• Basin: South Platte
• Water Division: 1
• Title: Tamarack Modeling Project Documentation - DRAFT
• Water Supply Pro - Doc Type: Report/Study

TABLE 4.2
WELL LABELS
• TAMARCK MODEL GIS DATABASE
Well Label
Ownershi
WR
DOW Recharge Well
WH
DOW Hill Well (old recharge wells located on
Sand Hills
WT
DOW Test Well
W
DOW miscellaneous well (domestic, stock,
windmill, etc.)
C
Condon
S
Sonnenber
U
USGS Test Hole
O
Other ownershi
5.0 DATA ANALYSIS
One hundred and forty -nine wells are included in the Tamarack Model GIS database. Geologic logs
were obtained for 88 of these wells. These well logs were reviewed and 10 cross - sections were
constructed based on the well logs. A base map showing the location of these cross - sections along with
the cross - sections themselves have been placed in the project files at the DOW office. The base map and
associated cross - sections were not attached to this memorandum because of the large size and volume of
the figures. However, four cross - sections located in the vicinity of the Tamarack site were presented in
USGS (1957) These cross - sections show the general geology of the study area and are more easily
reproduced. Figures 5.1 and 5.2 illustrate the cross - section locations and the cross - sections presented in
the USGS study.
Based on the analysis of the cross - section and well log data the following general interpretations were
made:
• The alluvial aquifer in the study area can be divided into two layers;
Layer 1: This top layer consists primarily of sands, fine sands, topsoil, and thin clay
layers. This layer is thicker in the southeastern dune section of the study area and
represents dune sand deposits. This layer can also be found in the river valley area and
could be derived from either dune sand deposits being blown into the river valley; or
flood plain deposits from the current South Platte River.
Layer 2: The lower layer consists primarily of gravel, coarse gravel, and gravel with
some sand. This layer represents the river channel deposits.
• • The base of the aquifer is easily identified either as clay, brule or shale on the geologic logs.
In picking the base of the aquifer, no distinction was made between the three formations.
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