On February 5, 2010, EPA inspectors Ellen Blake and Rebecca Glyn met with representatives of ADOT (Kurtis Harris (Tetra Tech contractor)) and Fisher Sand and Gravel (Mike Zunitch) at the State Route 179 Oak Creek Bridge Improvement Project. Steve Boschen, Resident Engineer (Point Engineering) joined the inspection around 11 a.m. Accompanying this group were Kent Haugerud and Buck Olberding of ADEQ’s Northern Regional Office and Sallie McGuire of the Army Corps of Engineers (ACOE), Los Angeles District, Phoenix Office. The purpose of the inspection was to evaluate compliance with the individual MS4 permit issued to ADOT (MS4 Permit) and Fisher’s compliance with Arizona’s Construction General Permit (CGP). Additionally, EPA and ACOE evaluated compliance with the CWA Section 404 permit issued to ADOT. The inspection began at 8:30 a.m. at the Oak Creek Pedestrian Bridge, located in Sedona, AZ.
Site Description: This project is a large, linear road improvement project. The areas of concern for this inspection included the improvements to State Route 179 between the village of Oak Creek and the City of Sedona, which discharge to Oak Creek through culverts and un-named tributaries. Additionally, within Sedona, ADOT/Fisher is working within Oak Creek to replace a vehicle bridge on SR 179. ADOT/Fisher has also installed a pedestrian bridge across Oak Creek in the same area. Oak Creek is a perennial river, which flows approximately 35 miles south to the Verde River. The Verde River is a perennial river, which flows approximately 70 miles from its confluence with Oak Creek to Horseshoe Reservoir. Additionally, ADEQ has designated Oak Creek as a Unique water under Arizona Administrative Code R18-11-112, which triggers additional monitoring and sampling requirements under the MS4 Permit and the CGP.
Observations: The inspection began at the eastern end of the pedestrian bridge, above the Garland slope. This slope is directly above the active channel (see Photos 0003, 0044). The slope was disturbed without adequate best management practices (BMPs) installed. At the foot of the slope were three ‘gator-eels’ (heavy logs to slow the flow of water). At the top of the slope, a small basin was installed to slow the flow of water (see Photo 0045). This basin was undersized, given the amount of run-on entering the site at this location. This slope has been unprotected since January 9, 2010, when ADOT/Fisher removed the last bridge abutment. Prior to the January 19-22 storm event, ADOT/Fisher installed three steel I-beams across the slope in an attempt to stabilize the slope. Because the I-beams served as dams rather than filters, they were inadequate and the slope eroded underneath and around the beams, discharging sediment to Oak Creek.
ADOT/Fisher monitors the weather forecasts frequently. As the project involves work in an active stream channel, ADOT also monitors warming trends to determine when snow melt will result in increased flows. However, although rain was forecast for the weekend, ADOT/Fisher had not made plans to address the exposed Garland slope. During the inspection, I spoke with them at length about this area and made several suggestions for possible BMPs until the permanent retaining wall is constructed.
ADOT/Fisher is working within Oak Creek channel to install pylons to support the bridge. During the inspection, flow in Oak Creek channel was restricted to the eastern side of the creek bed (see Photo 0005). The area where ADOT/Fisher is working