HomeMy WebLinkAboutAECOM - Virden Creek Floodwall - Supplemental Agmnt #1-12/11/2017AECOM
AECOM 319-232-6531 tel
501 Sycamore Street 319-232-0271 fax
Suite 222
Waterloo, Iowa 50703
www.aecom.com
CITY OF WATERLOO
VIRDEN CREEK FLOODWALL
U.S. HIGHWAY 63 TO 4TH STREET
SUPPLEMENTAL AGREEMENT NO. 1
WHEREAS, a Professional Services Agreement was entered into between City of Waterloo, Iowa,
(Client), and AECOM Technical Services, Inc. (ATS), of Waterloo, Iowa, dated June 27, 2011, for
increasing the flood protection level of the Virden Creek channel and earthen levee from U.S.
Highway 63 to Gates Park near 4th Street in Waterloo, Iowa; and
WHEREAS, the Client and .ATS now desire to enter into Supplemental Agreement No. 1 for
additional design, including collecting additional stream channel data, completing a hydrologic
review of the project area and preparing a hydraulic model of the stream using the new data.
NOW THEREFORE, it is mutually agreed to amend the original Professional Services Agreement
as follows:
Project Description
The original agreement between AECOM and the City of Waterloo for the Virden Creek
Floodwall Project assumed that the existing HEC -2 hydraulic model for this reach of Virden
Creek could be obtained from the U.S. Army Corps of Engineers or Iowa DNR. After
numerous unsuccessful attempts by both AECOM and the City to obtain this model, it was
requested that AECOM obtain the appropriate information and recreate the duplicate
effective HEC -2 hydraulic model in HEC -RAS. The HEC -RAS model will be utilized in the
preparation of the appropriate permits, LOMR and bid documents.
Also, during the geotechnical investigation, it was determined that the existing levees
surrounding the Virden Creek channel are constructed with sandy soils. This material is
prone to seepage issues which could be detrimental to the proposed floodwall. AECOM will
extend the existing concrete channel lining to the proposed wall to armor the entire channel
and negate the possible effects of seepage. This change in site conditions will require
additional design services.
11. Scope of Services
The Scope of Services for this supplemental agreement will encompass and include
detailed work, services, materials, equipment, personnel and supplies necessary to collect
additional stream channel data, flow line and structure data, complete a hydrologic review of
the project area, and prepare a hydraulic model of the stream using the new data. The
work will also include development of the necessary regulatory permits, preparation of a
LOMR and coordination with the corresponding regulatory agencies. This scope also
includes design of concrete channel lining for the unlined portion of the channel and
includes any additional earthwork design to allow for the channel lining installation. Quality
control reviews are also included for these extra work items. The following identifies tasks
leading to the completion of the additional work in this supplemental agreement:
Task 1 - Data Collection/Base Mapping Development. Field survey will be completed to
obtain cross section and structure information along Virden Creek for use in developing the
hydraulic model.
AECOM
Page 2
Task 2 - Hydrologic Review. The current hydrology of Virden Creek will be reviewed. It is
intended that the hydrology used in the modeling will match that of the current FIS.
Task 3 - Hydraulic Model Development/FIS Correlation. HEC -RAS software will be used to
prepare the hydraulic model for this reach of Virden Creek. After model development, the
HEC -RAS corrected effective model will be checked against the latest FIS mapping to
review how they correlate with each other. The corrected effective HEC -RAS model will
become the existing conditions model that will be used for proposed condition comparisons.
Task 4 - Permit Development/Regulatory Coordination. USACE Section 404 and IDNR
Floodplain permits will be prepared and submitted to the appropriate regulatory agencies for
review. AECOM will work with the agencies during the review process to ensure all
required information is provided in a timely manner.
Task 5 - LOMR Preparation and Coordination. A Letter of Map Revision (LOMR) will be
prepared and submitted to FEMA for review and approval. This task will require a LOMR
fee to be paid by the City of Waterloo prior to application submittal.
Task 6 - Additional Design. Channel lining will be designed to armor the unlined portion of
the existing channel. This will require grading design to be completed to allow for the new
channel lining installation.
Task 7 - QC Review and Administration. Reviews of Tasks 1-6 will be completed to ensure
the information being provided to the appropriate regulatory agencies and included in the
bid documents is complete and correct.
ASSUMPTIONS
1. The hydraulic modeling will result in a 100 -year flood elevation that is similar to the
FIS elevations that were used to set the current wall design heights so no
significant wall re -design will be necessary.
2. No USACE Section 408 review is required. Only a FEMA LOMB review of the
modeling will be required.
III. Compensation
Compensation for the above services will be on an hourly basis in accordance with Part VI
of the original agreement and shall be segregated from the fees in the original agreement.
The estimated fee is Fifty -Seven Thousand Five Hundred Dollars ($57,500.00).
IV. In all other respects, the obligations of the Client and the Consultant shall remain as
specified in the Professional Services Agreement dated June 27, 2011.
AECOM
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IN WITNESS WHEREOF, the parties hereto have executed this Supplemental Agreement No. 1 as
of the dates shown below:
AECOM TECHNICAL SERVICES, INC.
Douglas:Schindel, P.E.
Associate -Vice President
APPROVED FOR CITY OF WATERLOO
Date November 16, 2017
By: Date
Quentin Hart
Mayor
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