SPDSS_Task42-2_Phase2_DenverBasinAquiferConfiguration

• Title: SPDSS Task 42.2 - Denver Basin Region Aquifer Configuratioin - Phase 2
• Description: This Technical Memorandum was undertaken under Task 42.2, and summarizes the compilation, analysis and mapping of existing published aquifer configuration data for the Denver Basin Region.
• Decision Support - Doc Type: Task Memorandum
• Date: 2/13/2006
• DSS Category: Groundwater
• DSS: South Platte
• Basin: South Platte
• Contract/PO #: C153953
• Grant Type: Non-Reimbursable
• Bill Number: SB01-157, HB02-1152, SB03-110, HB04-1221, SB05-084, HB06-1313, SB07-122
• Prepared By: CDM

is the core table that links well information data with geophysical log, water level, and
aquifer test data.
The GEOPHLOGS table of HydroBase contains the geophysical well log picks for the
Denver Basin region aquifers. The GEOPHLOGS table contains the picks for the aquifer
top and bottom elevations, and picks for the net sand thickness. It also identifies which
logs were in the original Basic Data Report 1 (Van Slyke et al., 1986). This table is linked
to the WELLS table by the well_id field.
The REF_ELEV _ACCURACY table includes comments indicating the source and
accuracy of the elevation value.
The REF_LOC_ACCURACY table includes comments on the siting accuracy of the
location (X,Y) data.
2.2 Database Quality Control
Due to the significant number of geophysical well log picks that were obtained from
HydroBase and the complexity of the queries required to select picks for gridding each
surface, extensive quality assurance and control checks were performed. During the
initial querying of picks, detailed documentation of the spatial and attribute queries was
recorded and is included in Appendix A. Following the initial queries, a second round
of queries was performed following the written documentation. For approximately half
of the surfaces, a 100-percent check was performed, which verified that the initial query
and the repeat query were in agreement. In addition, the logic of each query was
reviewed to verify that the appropriate picks were being selected.
3.0 Results
This section presents the results of the data analysis and mapping that were discussed in
Sections 1 and 2. The aquifer top elevation, bottom elevation, and net sand thickness are
presented in a set of maps and described for each aquifer in descending order. As noted
in Section 1.1, the combined or aggregate thickness of materials interpreted from
geophysical logs as representing sandstone and siltstone within a given aquifer is
referred to herein as the net sand thickness. Database picks and control picks used to
develop the surface are also shown on each map. It should be noted that in some cases,
picks may be located outside of the extent of the aquifer, which indicates that the outline
shown is approximate and may not indicate the full extent of the aquifer in all cases. The
aquifer configuration is further characterized in a series of seven cross-sections that are
presented and discussed at the end of this section.
For all aquifers the top surface is contoured to the same geographic extent as the bottom
surface. Near the perimeter of the aquifer, the top of the aquifers have outcropped and
been eroded and the original top of the aquifer no longer exists. Thus, the upper limit of
the aquifer can be defined by ground surface except for where paloechannels and
extensive overburden soils exist. For this TM the top of the aquifer is defined as the
upper limit of the aquifer in its full areal extent, whether it be the original surface or the
SPDSS Phase 2 Task 42.2 TM -Final 13
2/13/06