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HomeMy WebLinkAboutIR 7157 INFORMAL REPORT TO CITY COUNCIL MEMBERS No.- 7157 To the Mayor and Members of the City Council November 25, 1986 Subject: FORTY OAKS STORM DRAIN to 7 On March 10, 1986, the City Council received a petition from 53 citizens, primarily residents of North Hampshire Street and the western part of Dallas Avenue, protesting the construction of Detention Pond No. 2, which is an integral link in the Forty Oaks Storm Drainage System. The staff reviewed the Forty Oaks design and reported to the Council (111 7108, April 22, 1986) that, while the detention pond might not significantly benefit the petitioners, it was essential for remedying down-stream flooding situa- tions. In the absence of the City Council 's instructions to the contrary, the staff has continued to work toward implementing the Forty Oaks drainage plan, and recommends the award of a contract for the final designs for Detention Ponds Nos. 2 and 3 with associated sanitary sewer and storm drain modifications. The City of Fort Worth has experienced extensive flooding over the years in the area known as Forty Oaks and, in 1981, the City commissioned the firm of Freese-Nichols, Inc. to study various alternatives to improve the situa- tion. The criteria used was protection against the 25 year flooding event since it was determined that protection against the 100 year event was not economically feasible, although the 100 year design is the current City of Fort Worth standard. Four alternatives were considered involving various combinations of pipe installation and storm water detention ponds. After extensive study, an alternate which uses both pipes and detention ponds was determined to be the best solution. The northeast portion of the plan (Attachment 'A' ), which uses only conventional pipe, has recently been con- structed at a cost of $1.8 million. The Phase I - Northeast System was designed and constructed according to the detention pond design. Changes in the overall system design at this point would require extensive reconstruc- tion of Emily Drive outfall on the recently completed northeast section of the system. The project to construct Detention Ponds No. 2 and No. 3, which are in the southeast and northwest portions of the Forty Oaks Drainage System, were included in the last bond issue at an estimated cost of $1.2 million. The reasons for selecting an alternate using detention ponds are: 1. It is much less disruptive to the neighborhood. The detention ponds avoid the installation of massive diameter storm drains which would destroy the streets, require extensive detours for extended periods of time, and disrupt utility service. 2. It is substantially cheaper. When the cost of street reconstruction is considered, the cost of the detention pond alternate is about one- third of the cost of the conventional solution of installing only underground storm drains. 3. It avoids massive utility line relocations, results in an additional indirect cost savings to the public, and shortens the effective length of the construction phase of the project. —ISSUED BY THE CITY MANAGER FORT WORTH, TEXAS INFORMAL REPORT TO CITY COUNCIL MEMBERS No. 7157 - -p.2 To the Mayor and Members of the City Council November 25, 1986 Subject: PS73 FORTY OAKS STORM DRAIN 4. It avoids additional project costs downstream by reducing the peak flow that must be handled at the outf all of the northeast portion of the system and under 1-30 at Woodhaven Drive. The City experienced a fatality at this location some years ago due to flooding. The reduced peak flow results in reduced flooding. 5. It is a commonly accepted method of handling storm water runoff. Detention ponds already exist in several other areas of the City. The City intends to fence the detention sites for safety purposes even though the ponds will be dry except during rainfalls. The ponds are expect- ed to completely drain in less than one hour after the rain has stopped. The fence should also preclude the nuisance of dumping which currently takes place on these particular lots from time to time. The City will plant shrubs or other screening material, if desired, to make the pond sites aesthetically pleasing. It is recognized that Detention Pond No. 2, to be located on Vinson Street between Tierney Road and Benton Street, does little to protect the high ground property on Dallas Street and North Hampshire Boulevard. It is pri- marily designed to protect the property-downstream between the pond and the outfall into Meadowbrook Golf Course. The high ground property on Dallas and North Hampshire is not subject to flooding. However, the City has an extensive record of flooding in the vicinity of the intersection of Benton Street and Dallas Avenue (see Attachment 'B' ) which the pond will correct. Of the 22 lots needed to construct Detention Pond No. 2, eleven have already been purchased (Attachment 'B' ). None are occupied with houses. Water and sewer lines have not been extended to Vinson Street. Cityouglas Harman Manager DH:di ISSUED BY THE CITY MANAGER FORT WORTH, TEXAS