I-10 Twin Peaks Traffic Interchange, Environmental Assessment

Affected Environment and Environmental Impacts October 2005
wash at the intersection of Twin Peaks Road and El Camino de Mañana, and three
wash crossing of Linda Vista Boulevard would impact Waters of the U.S.
Coordination with the Corps indicates the preferred alternative would require an
individual permit under Section 404 of the CWA and would require individual
water quality certification under Section 401 of the Act from ADEQ. The terms
and conditions of the Corps’ individual 404 Permit would be followed by the
contractor for work affecting jurisdictional waters within the project area.
Mitigation
The Town of Marana would obtain an individual Clean Water Act Section 404
permit from the U.S. Army Corps of Engineers and Section 401 Water Quality
Certification from the Arizona Department of Environmental Quality before
construction commences. The terms and conditions of the Clean Water Act
Section 404 permit from the U.S. Army Corps of Engineers and Section 401 Water
Quality Certification from the Arizona Department of Environmental Quality
would be followed by the contractor for work affecting jurisdictional waters within
the project area.
NPDES/AZPDES/SWPPP
Under Section 402(p) of the CWA, an AZPDES general permit from ADEQ is
required for construction activities when one acre or more of land would undergo
excavation and/or grading during construction. The main objectives of the
permitting program are to reduce erosion, minimize sedimentation, and eliminate the
discharge of non-storm water pollutants. All work that meets the disturbance
conditions must be permitted.
On August 22, 2005, the Ninth Circuit Court of Appeals vacated the United States
Environmental Protection Agency (EPA) delegation of Clean Water Act permitting
authority to the State of Arizona. The ruling questions the validity and status of
permits issued and managed under the Arizona Pollution Discharge System
(AZPDES), including the construction general permit for stormwater discharges and
individual AZPDES permits.
Existing Conditions
There are no storm water pollution prevention plans in place in the project area.
Impacts
No Build Alternative
Under the no build alternative, no land disturbance would occur and sediments
would not be discharged.
Preferred Alternative
The preferred alternative would excavate and/or grade more than one acre of land;
therefore, an AZPDES permit would be required.
Interstate 10 Traffic Interchange at
Twin Peaks/Linda Vista
4-21
Project No.: NH-010-D (AIW)
TRACS No.: 10 PM 236 H5838 01D