Loading...
HomeMy WebLinkAboutIR 8259 INFORMAL REPORT TO CITY COUNCIL MEMBERS No. 8259 of To the Mayor and Members of the City Council July 11, 2000 rtx� �y� Subject: Recent Flooding of Farmer's Branch in White Settlement On June 13th Mr. Claude Marchioni, a citizen of White Settlement who lives along Farmers Branch Creek, appeared before the Fort Worth City Council and requested that Fort Worth work with White Settlement to seek a solution to the flooding problems. Officials in the City of White Settlement have indicated that past and present development in the Westpoint area of west Fort Worth has significantly increased the amount of runoff entering their city. However, previous studies prepared by the United States Army Corps of Engineers (USACOE) indicate that the flooding conditions along Farmers Branch Creek are probably much more long standing and are heavily impacted by the lack of downstream drainage improvements within the City of White Settlement. Representatives of our Engineering Department and the City Manager's office have previously met with the current City Manager of White Settlement and his staff to discuss possible solutions to the flooding problems. Fallowing those discussions the Fort Worth staff concluded that based on various engineering studies conducted by the City of White Settlement and USACOE, that several downstream drainage improvements in White Settlement would provide a level of relief and should be accomplished. Following is a brief summary of work that has been performed by USACOE and private engineering firms pertaining to the Farmers Branch flooding issue. I am providing this information to you simply as background so you may better understand the nature of the flooding problems. Backgound In 1988 the City of White Settlement contacted the USACOE requesting that they do a study determining the feasibility of a flood protection project along Farmers Branch. A study was undertaken by USACOE with findings published in 1990. The 1990 USACOE report indicated that there were 45 houses in the 2-year floodplain, 79 houses in the 5-year floodplain, 96 in the 10-year floodplain, 159 in the 50-year floodplain and 187 in the 100-year floodplain in the study area for existing conditions. USACOE investigated a channelization solution for Farmers Branch that involved constructing concrete-lined channels on four different segments of the stream. The cost for these improvements was estimated at $4.5 million with an average annual benefit of $273,800. USACOE determined that the proposed improvements would likely create increased flooding downstream due to increased flows and the restrictions caused by the Carswell INFORMAL REPORT TO CITY COUNCIL MEMBERS No. 8259 &0—TER�4�a To the Mayor and Members of the City Council N, July 11, 2000 IF Page 2 of 3 Subject: ion Recent Flooding of Farmer's Branch in White Settlement runway culverts. For these reasons the channelization solution was determined to be not economically feasible. USACOE then looked at the feasibility of purchasing and/or relocating homes along Farmers Branch. As the result of their investigation, USACOE recommended the relocation of 15 residential structures. These 15 residences were considered the most severely damaged structures in terms of expected annual flood damage. The cost for the relocation was estimated at $725,200 with an annual average benefit of $37,900. According to USACOE the City of White Settlement did not sign a contract with them to proceed with the buyout plan. It is believed, however, that the City of White Settlement acted independently and bought several of the structures. In doing so, the City of White Settlement forfeited USACOE participation in the amount of 75% of the buyout costs. In 1998, Kimley-Horn and Associates prepared a report for the City of White Settlement entitled, Farmers Branch Detention Feasibility Study. In their report they reference a 1994 USACOE study. Although we have been unable to obtain a copy of this report at this time, Staff understands that it is an update of the 1990 report. The 1994 report recommends the evacuation of 11 structures. The reduction of severely damaged structures from 15 to 11 is likely the result of the buyout that the City of White Settlement did without USACOE participation. The 1998 Kimley-Horn report recommends the construction of detention ponds within the City of White Settlement and/or the City of Fort Worth to reduce the discharges into Farmers Branch. The three alternatives presented range in costs between $1.7 and $4.1M excluding the cost of land acquisition. The Kimley-Horn report acknowledges that the cost of the least cost detention pond alternative would cost more than two times the cost of buying out the affected residential structures in the 5-year floodplain. The report states," If frequent flooding is a concern, a buyout and some improvements to roadway crossings might be the best solution. If major flooding is the concern, then detention basins might be the best solution." While the detention pond alternatives may reduce the magnitude of flooding to the 11 structures noted in the 1994 Corps report it does not remove them from the floodplain. The recommended improvements would also not bring relief to an additional 79 residences that are located within the 5-year floodplain since the detention basin alternatives suggested by Kimley-Horn all bypass the 5-year storm discharge directly to the creek. ISSUED BY THE CITY MANAGER FORT WORTH,TEXAS INFORMAL REPORT TO CITY COUNCIL MEMBERS No. 8259 de0TE,9 To the Mayor and Members of the City Council July 11, 2000 Page 3 of 3 1rx 0,- Subject: Recent Flooding of Farmer's Branch in White Settlement Correspondence material from Kimley-Horn to the City of White Settlement suggests that the development in the upstream watershed (WestPoint) has led to a 17% increase in runoff from 1986 to 1996, however the Department of Engineering does not agree with Kimley-Horns assessments. Proposed Action The Fort Worth staff is prepared to work with White Settlement staff if requested and as appropriate, however the City of Fort Worth should not take the lead in resolving drainage problems resulting from conditions over which the City of White Settlement has control. Attached is a copy of a Fort Worth Star Telegram article that appeared in April of this year (prior to the recent flooding). The article provides some additional insight as to 'the City of White Settlement Council's recent actions. If you have any questions concerning this issue, please feel free to contact me. Bob Terrell City Manager ISSUED BY THE CITY MANAGER FORT WORTH,TEXAS