Accession Number : ADA184320

Title :   Environmental Assessment: Johnson County Road F-20 Bypass, Johnson County, Iowa.

Corporate Author : ARMY ENGINEER DISTRICT ROCK ISLAND IL

PDF Url : ADA184320

Report Date : Aug 1986

Pagination or Media Count : 28

Abstract : The Rock Island District received an easement request from the country engineer of Johnson County, Iowa, to construct a gravel bypass road for Country Road F-20 on Corps Tract F-583. According to the county, certain segments of County Road F-20 become impassable to traffic when Coralville Lake reaches and elevation of approximately 706 feet NGVD (National Geodetic Vertical Datum). The county wants to construct a high water bypass road north of existing F-20 along the 715 NGVD contour elevation. The road would have a 22-foot-wide surface and 60-foot-wide right-of-way, 2:1 foreslopes, and a minimal ditch. Two 15-inch metal pipe culverts will be required to convey flows from a small, intermittent stream. Approximately 3.5 acres will be cleared of vegetation and reshaped to provide an adequate road foundation. Most of this grading will take place between the existing F-20 right-of-way and the new bypass road. The county has stated that the road will be used only during high water and that access will be restricted other times to prevent unauthorized activities. It also has been proposed that the road remain accessible for use as a parking area. People now using the adjacent Hawkeye Wildlife Area must park along F-20. The ACE finding is one of 'no significant impact'.

Descriptors :   *CONSTRUCTION, ROADS, GRAVEL, CIVIL ENGINEERING, ENVIRONMENTAL IMPACT, FLOODING, IOWA

Subject Categories : Civil Engineering

Distribution Statement : APPROVED FOR PUBLIC RELEASE