PERMFILE63706

• Permit No: M2006046
• IBM Index Class Name: Permit File
• Doc Date: 1/3/2007
• Doc Name: Response to 2nd Adequacy Review
• From: Banks and Gesso, LLC
• To: DRMS
• Media Type: D
• Archive: No

Mr. Alex Schatz
December 29, 2006
Page 2 of 6
21.b. DRMS requests a discussion of the depth to ground water across the site and
particularly beneath existing wetlands alyd woody riparian vegetation areas, along with a
discussion of the seasonal variation in the level. In additional DRMS also requests a
discussion of the hydraulic gradient across the site and the directimr of ground water flow
for the alluvial aquifer.
Our field trip to the site on December 5, 2006 revealed that there are more
monitoring and observation wells existing on the site than we had been led to believe
fi~otn the indication of only three wells as per maps produced by Banks acrd Gesso. The
existence of these additional monitoring wells has been confirmed via the map and
spreadsheet provided us by Mr. Chris Manera, P.E., of Colorado River Engineering, Inc.
This information shows that there are 12 different monitoring points across the site along
with a staff gage set at the edge of the river in the northeast comer of the site and just
south of the I-70 highway bridge over the river. The existence of these additional data
points should satisfy the Division request for additional monitoring points as per 21.c.,
below. However, even the three monitor wells referred to by DRMS are sufficient to
define the gradient across the site and to develop an adequate picture of the depth to
ground water across the site, as it is clear that conditions are relatively consistent over
much if not all of the property.
Our observations of the site during June and December has confirnied that the
depth to water in the vicinity of the existing wetlands areas is essentially zero, with
standing water and or saturated conditions noted in these areas. In the areas significant
stands of the woody riparian species, located predominantly in the northeastern portion of
the property lying south of the highway, it was observed during our field visits that there
are small topographic changes in these areas that result in greater depth to ground water,
although the magnitudes are still relatively minor being on the order of one to four feet.
We do also have May 2006 and October 2006 data that reflect minimal change in the
depth to water over the site and, based on this data, it appears that there can be expected
very minimal changes in water levels on the site over the cow-se of a year with the
possible exception of the spring flood period when the Colorado River is at highest stage.
Finally, the hydraulic gradient across the developed on the basis of the May 2006
data is generally to the northwest and reflects the observed higher water table to the south
and east across the site.
21.c. DRMS requests additional monitoring wells to be located on the properly based on
their understanding that only three such wells currently exist. Specific up- and down-
gradient locations were suggested by the DRMS; we note that our interpretation of the
ground water data indicate a differing gradient than that assumed by DRMS, and as noted
in 21.6., above.
As recognized by the State, three monitoring wells/piezometers are located on the
subject property. Additionally, 12 piezometers were installed on the property in 2006.
Ground water level measurements were collected by Colorado River Engineering, Inc.,
Martin and Wood Water Consultants, Inc.