04-15-1999 Regular Meeting and Public Hearing of the La Porte Planning and Zoning Commission

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CITY OF LA PORTE, TX CRS ACTIVITY 510 FLOODPLAIN MANAGEMENT PLAN Often accurate readings of high wind gusts during iondfall are impossible because the anemometers at reporting wind stations are ripped from their foundations. Wnd is responsible for much of the stnrctural damage caused by hurricanes. High winds uproot trees and tear down power lines. The maximum winds from fast moving and powerful storms may remain high, even when the storm is well inland. Often this is actual wind speed combined with the speed of the storm. Flood Hazard Data During two 1998 tropical storms, Charley (Aug, 1998) and Frances (Sep, 1998) produced storm surges of 2.5 feet, and 6-8 feet, respectively. The Flood Insurance Rate Map (FIRM) for La Porte shows the Base Flood Elevation (BFE) as low as 15 feet for the VE area adjacent to Galveston Bay, and BFE of 12 feet for zones AE near the Bay. The FIRM designates two types of floodplain: A zone and V zone. All properties directly adjacent to Galveston Bay are designated as VE — "coastal high hazard area.' Properties farther inland are designated as AE. These properties are subject to flooding from either riverine or storm surge events. The coastal high hazard area is subject to the combination of storm surge and wave hazard. This area is where the waves during the base flood are at least three feet higher than the stillwater elevation. This is the most dangerous toward the south coast of La Porte (where VE zone is more prevalent). Related plans and studies include the following: • Clear Creek Regional Flood Control Plan (July 1991) — This study, prepared by Dannenbaum Engineering, addressed the tributaries of Clear Creek. however, A104-12 is not addressed in this study. • Hydrologic and Hydraulic Study for Interconnect of HCFCD Unit B112-02-00 to Unit B109-00-00 and HCFCD RN aortal Detention Site Unit 8512-01-00 (April 1997) — This report, prepared by Wilbur Smith Associates, describes the impacts of the diversion of Willow Springs Bayou (13112-02-00) to Spring Gully (13109-00-00). This report also presents the design of a regional detention site that provides flood protection for a portion of La Porte. • Study of Flood Control Improvements for HCFCD Unit F101 (September 1987) — This report, by Landev Engineers, recommended channel improvements that are being implemented. This study also indicates significant channel improvements from Galveston Bay upstream to Lomax School Road, with detention being required in the portions of the watershed north of SH 225. • Study of Flood Control Improvements for Little Cedar Bayou F216��-00� (September 1989) — Prepared by Epsey, Hutson & Associates. City of La Porte Page 6 of 25 Planning Deiparnneat, rmh May 13, 1999