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Home My WebLink AboutContract 38800-A2 f May 31, 2011 Mr. Steven Eubanks, P.E., CFM CITY SECRETARY y��— Senior Professional Engineer CONTRACT NO3d�O Storm Water Management Transportation and Public Works Department 1000 Throckmorton Street Fort Worth, Texas 76102 RE: Amendment No. 2 Eastland Creek Open Channel Study City Project No. SWS-019 Dear Mr. Eubanks: As we discussed at our meetings on January 21, 2011 and February 24, 2011, this amendment revises the previously approved Eastland Creek Open Channel Study, City Secretary Contract No. 38800, City Project No. SWS-019. Specifically, this amendment includes the following two tasks: Task 1: Comparing peak flow rates resulting from the storm drain and overland flow paths, and Task 2: Additional field survey, 2D and HEC-RAS split flow modeling along Jennifer Court to more accurately map the floodplain. Task 1: Stone Drain versus Overland Flow Path Analysis The existing storm drain system in the upper three sub-basins only captures the 5-year discharge, and during the 100-year event much of the flow travels overland. A sensitivity analysis will evaluate the importance of Tc calculations on peak discharges and subsequent floodplain mapping. A combined method was suggested to allow the runoff captured by the storm drain system to be based on the storm drain Tc, but allow the excess runoff to be based on overland paths. Sub-basins with two flow paths will be input into the HEC-HMS model for each sub-basin with a significant storm drain system. The results represent an average 30% reduction in the peak discharge values for use in the floodplain mapping. The specific work to be included in this amendment to analyze the Tc for the storm drain versus overland flow paths in the hydrologic model is as follows: • Convert design rainfall to incremental amounts • Copy sub-basins in HMS and input flow path Tc and loss rates • Finalize HMS mm_gnd summarize results in a memo. OFFICIAL RECORD CITY SECRETARY FT. WORTH, TX NM ENiwwwrh>♦.Ms. 210 E.300 Sh" Phone:(817)333-M sub 300 Fu:(817)333.2818 Fad WoM,TX 781024002 www.hNm.com 8 Mr. Steven Eubanks, P.E., CFM May 31, 2011 Page 2 of 3 Task 2: 2D Modeling and HEC-RAS Split Flow along Jennifer Court In the initial floodplain mapping from HEC-GeoRAS in the Jennifer Court area, the assumption of a constant WSEL across the entire cross section will place 3 rows of houses in the 1%-chance floodplain. However, once the overflow between the 1e1 row of houses reaches Jennifer Court, it speeds up and flows down to Eastland Street, and does not inundate the 2"d or 3rd row of houses. Modeling this situation correctly in the LOMR will require a HEC- RAS split flow reach, guided by a 2D hydraulic model of the area. The specific work to be included in this amendment to develop the 2D modeling and a HEC-RAS split flow reach a"Jennifer Court is as follows: • Import RAS Geo File/boundary conditions/flow analysis • Define 2D area polygon, meshing &2D model run • Incorporate surrey points to 2D model/Manually define 2D elements for 2D mesh • Left bank 2D split flow modeling • Incorporate survey points to RAS model • Model lateral weir in RAS • Results analysis/2D vs RAS comparison • Update Hydraulic Report/QAQC Schedule HDR estimates that it will take an additional 1 week for Task 1 to finalize the Tc analysis and 3 weeks for Task 2 to add the 2D and HEC-RAS split flow modeling. The remainder of the project schedule will remain the same. Deliverables Deliverables will remain the same as outlined in the contract. Man EM 000doe.hM. 210 E.r Shed Phow:(SM 333-2800 Suits 3W Fa:017)>334818 Fat Worth,Tx 76102-4W wrw Affine.oan J Mr. Steven Eubanks, P.E., CFM May 31, 2011 Page 3 of 3 Fee Estimate HDR is proposing to complete the additional services outlined above for a lump sum fee of$37,510. Invoices will be sent monthly and will be based on a percent complete of the lump sum fee. HDR's fees for the aforementioned services are itemized below: Task 1 - Professional Services $ 5,680.00 Task 2- Professional Services $ 15,780.00 Task 2-Sub-Contracted Services(ANA) $ 11,200.00 Task 1 and 2 Expenses $ 4,850.00 Total Contract Amendment No. 2 Value: _ $ 37.510.00 Contract value revisions are as foik)ws: Professional Services $ 225,352.00 Amendment request No. 1: $ 7,560.00 Amendment request No. 2: $ 37.510.00 TOTAL CONTRACT AMOUNT $ 270,422.00 If you have any questions or there is additional documentation needed for this work, please contact Mr. Curtis Beitel, P.E. at(817)333-2817. Sincerely Dennis Schulze, P.E. Vice President HDR Engineering, Inc. OFFICIAL RECORD CITY SECRETARY FT. WORTH, TX MM Es6Mccdme.Inc. 210 E.309 SMM Pla :(817)333-M Suit 300 Fa:(017)3332616 Fad Woflh,TX 7610240M www.hdrinc.0" AMENDMENT NO. 2 STATE OF TEXAS S CITY SECRETARY CONTRACT NO.38800 (No M&C Needed) COUNTY OF TARRANT S WHEREAS, the City of Fort Worth (City) and HDR Engineering, Inc. , (Engineer) made and entered into City Secretary Contract No. 38800, (M&C # C-23582) which was executed by the City Manager on the 7th day of July, 2009, and Amendment No. 1 which was executed administratively by the City Manager on the 20th day of April, 2011; WHEREAS, the Contract involves engineering services for the following project: Eastland Creek Open Channel Study - Study No. SWS-019; WHEREAS, it has become necessary to execute Amendment No. 2 to said Contract to include an increased scope of work and revised maximum fee; NOW THEREFORE, City and Engineer, acting herein by and through their duly authorized representatives, enter into the following agreement which amends the Contract: 1 . Article I of the Contract is amended to include the additional engineering services specified in a proposal letter dated May 31, 2011, a copy of which is attached hereto and incorporated herein. The cost to City for the additional design services to be performed by Engineer total $37,510. 00. 2 . Article II of the Contract is amended to provide for an increase in the maximum fee to be paid to Engineer for all work and services performed under the Contract, as amended, so that the total fee paid by the City for all work and services shall not exceed the sum of $270,422 .00. City of Fort Worth,Texas Amendment to Engineering Agreement PMO Official Release Date 10.01 2010 Page 1 of 2 3. All other provisions of the Contract which are not expressly amended herein shall remain in full force and effect. EXECUTED on this the 6 day of June, 2011, in Fort Worth, Tarrant County, Texas. ATTES a� ��silo �a4 'n7y,, p 0000°OOp00" 11�rtj Hendrix G.. a d 6i ty Secretary 000 0Yx 0 %'��'00000000 oo 400 Ay APPROVAL RECOMMENDED: aa��x � APPROVED: C-74f Q"�' Douglas W' rsig, P.E. , Dir ctor, Fernando Costa Transportation and Public Works Assistant City Manager HDR Engineering, Inc. NEER By. Name: Dennis Schulze, P.E. Vice President 210 East 3rd Street, Suite 300 - --- Fort Worth, Texas 76102 OFFICIAL RECORD CITY SECRETARY APPROVED AS TO FORM AND LEGALITY: FT. WORTH, TX Q) 5 -- is City Attorney City of Fort Worlh,Texas AmerWrnerrl W E.Wkw ring Agreement PMO oAcisl Release Otle:6,18.2010 ; Pape 2 of 2 h� .. ` + [j' i[t fy MEN ° Rf N N ow 3 pM pM 3� h.Y I N� IVOR �,t N 03�st,ia'f41A � d f m m N O l Mg. bt S BMW 1 m m 1 sp ,_ Sol N a �� Z .0 F y ♦ ° O h �N .5kk3 S 6 e W T �ilk U i O atti- A �r 2 N 2 g Cl O(ryryQQ'' ^o N x n 2 KH ism � � A �'a� w o ��SPi ■ a u v s .. o c ;' F�� 5 �� T polo � f z ? UlW O S W 2 ��+', K��,, sic W y� f' L os l� IL fir`