CITY OF FRIENDSWOOD February 13, 2006 CLEAR CREEK WATERSHED PRELIMINARY NED ALTERNATIVES ANALYSIS

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1 CITY OF FRIENDSWOOD February 13, 2006 CLEAR CREEK WATERSHED PRELIMINARY NED ALTERNATIVES ANALYSIS

2 Agenda Purpose Organizations/Entities Background Planning Process Preliminary NED Results Alternatives Comparison

3 Purpose The purpose of this presentation is to brief City Council on: Clear Creek Watershed Steering Committee (CCWSC) activities United States Army Corps of Engineers (USACE) planning process Present the various flood reduction alternatives considered by USACE in the City of Friendswood

4 Organizations/Entities LOCAL SPONSORS Harris County Flood Control District Galveston County Brazoria Drainage District #4 ROLES Right-of-Way Acquisition Utility and Pipeline Relocation Bridge Modification or Relocation Operate and Maintain Project After Construction

5 Organizations/Entities (Cont d) Clear Creek Watershed Steering Committee Composed of entities in the Watershed working together to: Reduce Flooding Cost sharing funds from State and Federal Agencies Participate in Regional Planning Negotiate local cooperation agreements with the Texas Water Development Board or others Cooperate in pursuit of common goals

6 Organizations/Entities (Cont d) Clear Creek Watershed Steering Committee Membership: Brazoria County Conservation and Reclamation District #3 Brazoria Drainage District No. 4 City of Friendswood City of Houston City of League City City of Pasadena City of Pearland Clear Lake Area Council of Cities Fort Bend County Drainage District Galveston County Harris County Flood Control District Galveston County Consolidated Drainage District

7 Organizations/Entities (Cont d) Clear Creek Watershed Citizens Advisory Committee Advises and provides input to Sponsors regarding the USACE General Revaluation Report Membership Citizens living in the Watershed Consultants

8 BACKGROUND CLEAR CREEK WATERSHED TIME LINE 1962 Flood Control Act of 1962 authorized USACE to study flood damage reduction on Clear Creek 1968 A flood damage reduction project involving channelization was authorized by Congress Post-authorization studies were begun and public meetings were held Second flood damage reduction project recommended in a Post-authorization Planning Report USACE, Harris County Flood Control District (HCFCD), and Galveston County sign a Local Cooperation Agreement making HCFCD and Galveston County local sponsors of the project. May 1989 The Clear Creek Watershed Steering Committee (CCWSC) is formed July 1990 Interlocal Agreement between CCWSC Members 1991 The second outlet control structure on Clear Lake is completed May 1995 CCWSC supported the creation of a District HB The second outlet channel on Clear Lake is completed (25,000 cfs)

9 BACKGROUND (Cont d) CLEAR CREEK WATERSHED TIME LINE 1997 Local sponsors recommend an alternative flood damage reduction plan to USACE addressing public opposition to channelization 1999 USACE agrees to re-evaluate the Clear Creek Project and begins work on the General Reevaluation Report (GRR) 2001 USACE and local sponsors agree to add the tributaries of Clear Creek, expanding the scope of the study to the watershed at large. June 2001 Tropical Storm Allison causes severe flooding in Clear Creek Watershed December Preliminary maps on Clear Creek (Harris County) May 2005 Began mapping update on all tributaries of Clear Creek September Preliminary NED plan from the GRR October 2005 Resolution R documenting COF concerns with Preliminary NED November 2005 Letter of concerns regarding the Preliminary NED from Sponsors to USACE Mid 2006 GRR is scheduled for completion (locally preferred plan)

10 PLANNING PROCESS STEPS The principles and guidelines prescribed the following six-step planning process to solve problems. 1. Identify water resource problems in the study area 2. Collect data on the problems identified 3. Develop alternatives to solve the problems 4. Evaluate the effects of the alternatives 5. Compare alternatives 6. Select a plan for recommendation or decide to take no action The alternative plan with the greatest net economic benefits consistent with protecting the nation s environment is normally selected. Any exception may be granted by the Secretary of the Army.

11 Preliminary NED Change in Water Surface Elevations within the City of Friendswood Water Elev. Description Change (Ft.) Dixie Farm Road 0.16 Conf. w / MUD Gully Conf. w / Turkey Creek FM Conf. w / Mary's Creek Whispering Pines Conf. w / Cow art Creek FM

12 ALTERNATIVES COMPARISON A. CS b Selective clearing 20 outside of Clear Creek s banks - Limits between FM 2351 and Chigger Creek B. EHFB b Enlarge Clear Creek s high flow bypasses BW and deepen by 2 - Limits from FM 2351 to FM 528 C. C4 b Trapezoidal channel - 4:1 S.S. and 60 /65 BW - Limits between FM 2351 to West Bay Area Blvd. D. TC1 b Offline detention on Turkey Creek - Surface Area = 79 Acres - Volume = 602 Ac-Ft. E. MG1 b Offline detention on Mud Gully - Surface Area = 102 Acres - Volume 1386 Ac-Ft.

14 ALTERNATIVES COMPARISON Downstream WSEL Cost Impact Change Million Alternative (cfs) (ft.) ($) B/C A. Selective Clearing to B. High Water Bypass to FM 2351 to FM 528 C. Channelization to FM 2351 to FM 528 D. Turkey Creek Pond to E. Mud Gully Pond to

15 Other Alternatives for Additional Flood Stage Reduction in Friendswood Additional detention storage on tributaries - No downstream flow/stage impacts Channelization in the Friendswood reach - Downstream flow/stage impacts is a concern

Clear Creek, Texas. Flood Risk Management. Final General Reevaluation Report

Clear Creek, Texas. Flood Risk Management. Final General Reevaluation Report U.S. Army Corps of Engineers Galveston District Southwestern Division Clear Creek, Texas Flood Risk Management Final General Reevaluation Report October 2012 CLEAR CREEK, TEXAS FLOOD RISK MANAGEMENT EXECUTIVE