This project crosses a stream inhabited by the Topeka shiner, a federally endangered species. The Contractor shall implement the following conditions to minimize the impact of a stream crossing construction on the Topeka shiner. Failure to implement the following conditions may result in violation of the Endangered Species Act. II. MATERIALS (None Required) III. CONSTRUCTION REQUIREMENTS A. GENERAL CONSTRUCTION The Contractor shall not perform construction activities within the stream, along the stream banks, and in areas that drain into the stream unless comprehensive and effective best management practices (BMPs), that will prevent sediment, fuels, chemicals, concrete wash water, and other pollutants from entering into the stream, are in place and functioning properly. The Contractor shall maintain erosion and sediment controls in good working condition until the Contractor restores vegetation to 70% of the pre-disturbance condition. Erosion and sediment controls implemented shall be those appropriate for the specific site conditions. The Contractor shall not place fill material below the ordinary high water elevation except as directed by the plans or as allowed by the United States Army Corps of Engineers 404 permit. B. MEASUREMENT OF STREAM TURBIDITY The Contractor shall not allow construction activities that produce sediment discharges that increase stream turbidity (i.e., water clarity) by more than 50 Nephelometric Turbidity Units (NTU) over the background turbidity level. The Contractor shall cease all construction methods that produce sediment discharges exceeding this turbidity standard and may resume only after the Engineer has approved an acceptable plan. The Contractor shall immediately notify the Engineer if the Contractor suspects that stream turbidity has been increased. The Engineer will monitor the turbidity during all stages of the project. 1. Turbidity Meter and Maintenance: The Engineer will take measurements with a Global Water WQ 770 turbidity meter or equivalent. The Engineer will maintain and operate the turbidity meters in accordance with manufacturer specifications and technical manual. 2. Definition of Turbidity Sample: The definition of a turbidity sample is the average of five measurements taken at a sampling location. 3. Obtaining a Turbidity Sample: The Engineer will submerge the sensor of the turbidity meter in the stream and allow the sensor to run continuously for at least one minute before taking the first turbidity measurement. The Engineer will take subsequent turbidity measurements at thirty second intervals until five measurements have been obtained. The Engineer will take turbidity measurements in accordance with manufacturer specifications and technical manual.
