PERMFILE64543

• Permit No: M2003037
• IBM Index Class Name: Permit File
• Doc Date: 9/5/2003
• Doc Name: Haldorson Water
• From: Banks and Gesso LLC
• To: DMG
• Media Type: D
• Archive: No

SEP-05-2003 FRI 09;27 RM BANKS AND GESSO LLC FAX N0, 303 274 8329
P, 03
• Page 2 September 4, 2003
In the case of a gravel ptt two conditions would have to occur before the pit could Impact local
groundwater conditions. First the pit must obviously be dug to a depth below the groundwater
surface. This common occurrence results in the formation of a pond in the bottom of the pit Once
the pond has formed and stabilized, as described above, this condition has lime or no Impact on the
groundwater surtace. The second wndidon is that the water in the pond must be lowered below the
elevation of the surrounding groundwater in order to forth a cone of depression. This could occur
through pumping or a drain system. Evaporation and increased infifbadon into the underlying
bedrock material will also oxur if ponds are formed and would add to the drawdown caused by
pumping. However, their impact on the gradient and elevation of the groundwater surface would
nortnafy be quite small.
2. Hydrologic balance
The.hydrologic balance of the groundwater system is an accounting, over time, of the water flowing into
and out of a defined system .The change in the amount of water stored or released from the system
also enters Into the balance. If we use the block of earth below the Haldorson site as the system then
we can identify the components of the hydrologic balance.
In the historic condtion (without the gravel mine) the inflow consists of rainfall, applied irrigation water,
groundwater flow in through the sides of the system coming from up-gradient regions and any surface
water drainage onto the site. Outflows consist of groundwater flow out through the sides of the system
tp down-gradient regions, evapotrenspiration from crops and any surface water drainage leaving the
site. There is no apprecable change in storage of water on the site on an annual basis.
/ In the case with the proposed gravel mine the Inflow consists of rainfall, groundwater flow In through the
sides of the system coming from up-gradient regions, any surface water drainage on to the site and
project water used for mine operation (note that the applicant has indicated that initially there will be no
need for operation water. It is part of this discussion because k may effect the balance in the future) .
Outflows consist of groundwater flow out through the sides of the system todown-gradient na~fons,
evaporation from ponds, seepage through the bottom of ponds and any surface water drainage leaving
the site. There wiN be no appreciable change in storege of water on the site. Note that this assumes
that no water will be pumped or drained out of the system unless it travels through one of the
mentioned components.
When compared, the historic and proposed conditons differ by only a few factors. On the inflow side
the historic condition includes aop irtigafian water where the proposed has mine operation water. For
the outflows, the historic case has crop evapotranspiration and the proposed has pond evaporation and
seepage. Any differences in the magnitude of these or the other factors, between the historic and
proposed cases, must be attributable to a change in one or more of the remaining factors.
Based on this model I see Iitde difference between the historic and proposed cases that can he
atMbuted directly to the gravel mine. The rainfall and groundwater flaw into the system will remain the
same. As per the proposed development plan (dry pit), the groundwater outflow will be virtually
unchanged. The most significant Impact will be the loss of applied Irtlgation water as a system Inflow.
This same impact is being felt throughout the area as agricultural land is convert to residential and
commercial uses. Ultlmatety the reclamation plan ells for reclaiming the area to cropland and hence a
return of applied irrigation water.
3. pry versus Wet Pft
The proposed mfning plan states that the operation will be a dry pit. Based on the hydrology of the area
it is very likely that a groundwater surface does exists above the shale bedrock, at {east during the
irrigation season. Six test holes were augured in a north-south alignment across the proposed site. The
four holes toward the north were to a depth of 60 feet and the two southern holes were augured to 32
feet. These depths equal or exceed the maximum potential depth of exgvation in the various phases
of the proposed project developmenrt. Water was not encountered in any of the test holes. Since they