I-10 Twin Peaks Traffic Interchange, Environmental Assessment
I-10 Twin Peaks Traffic Interchange, Environmental Assessment
I-10 Twin Peaks Traffic Interchange, Environmental Assessment
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Affected Environment and <strong>Environmental</strong> Impacts October 2005<br />
Mitigation<br />
No mitigation measures are required because the preferred alternative would have<br />
no effects on agricultural land.<br />
Conclusion<br />
The preferred action would not alter or impact slopes or substantially effect<br />
important topographic features in the project area. Although disturbed soils in the<br />
project area would be vulnerable to water and wind erosion, the SWPPP and air<br />
quality permitting regulations followed for this project would result in no impacts<br />
to area soils. The preferred alternative would have no effects on the geological<br />
setting or mineral resources in the project area and no prime, unique, or farmland<br />
of state or local importance exists within the project area; therefore, the preferred<br />
alternative would have no effects on agricultural land.<br />
Water Resources<br />
The following sections discuss surface water and groundwater conditions within<br />
the study area. Surface water resource concerns include potential impacts to rivers<br />
and intermittent washes. The Santa Cruz River and numerous washes that drain<br />
into the Santa Cruz River are the dominant surface water features in the study area.<br />
Groundwater is defined as stored water beneath the ground surface that can be<br />
used to supply wells and springs. This water is stored in natural underground<br />
reservoirs composed of loose rock fragments called aquifers.<br />
Surface Water<br />
Existing Conditions<br />
The main surface water drainage in the study area is the Santa Cruz River, which<br />
runs approximately parallel to and west of I-<strong>10</strong> within the study area. The Santa<br />
Cruz River originates in the San Rafael Valley in Arizona, and then flows south<br />
into Mexico before bending west and north and reentering the United States east of<br />
Nogales, Arizona. Near the study area, a perennial nine-mile reach of the Santa<br />
Cruz River flows north consisting of treated effluent discharged into the channel<br />
by the Ina Road and Roger Road Wastewater Treatment Plants. According to the<br />
Arizona Department of <strong>Environmental</strong> Quality (ADEQ), the portion of the Santa<br />
Cruz River that flows through the study area is classified as Effluent Dominated<br />
Waters. Swimming and fishing are deemed not allowable uses for the Santa Cruz<br />
River, but it is suitable for bird-watching and other terrestrial activities. With the<br />
exception of this effluent dominated reach, the remainder of the Santa Cruz River<br />
within the study area is intermittent and flows in response to rainfall events.<br />
The Canada del Oro Wash and many minor unnamed washes drain into the Santa<br />
Cruz River within the study area. All of these washes are ephemeral, flowing only<br />
in response to rainfall events. According to the Drainage Report prepared for this<br />
study, the Canada del Oro Wash and several minor unnamed washes originate in<br />
Interstate <strong>10</strong> <strong>Traffic</strong> <strong>Interchange</strong> at<br />
<strong>Twin</strong> <strong>Peaks</strong>/Linda Vista<br />
4-9<br />
Project No.: NH-0<strong>10</strong>-D (AIW)<br />
TRACS No.: <strong>10</strong> PM 236 H5838 01D
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