HomeMy WebLinkAboutContract 38567-A1 (2) AMENDMENT NO. 1
STATE OF TEXAS S CITY SECRETARY CONTRACT NO. ,,JS(p-J-
(No M&C Needed)
COUNTY OF TARRANT S
WHEREAS, the City of Fort Worth (City) and Jerry Parche'
Consulting Engineers, (Engineer) made and entered into City
Secretary Contract No. 38567 , (the Contract) which was executed
administratively by the City Manager on the 14 day of May, 2009;
and
WHEREAS, the Contract involves engineering services for the
following project:
Warner Creek Open Channel Study, Project No. Study No. SWS-011
WHEREAS, it has become necessary to execute Amendment No. 1
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 30 day of March, 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 $11, 600.00 .
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 $101,100 .00.
rOFFICIAL RECORD
City of Fort Worth,Texas ECRETARYAmendment to Engineering Agreement PMO Official Release Date:10.01.2010 ORTH� TX
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 day of , 2011, in Fort Worth,
Tarrant County, Texas.
ATTEST:
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Marty Hen xAy�r`y 00000oc
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City Secretary xy �Oo °o��9d� NO M&C RE-QUIRE
APPROVAL RECOMMENDED: 000 0 �d APPROVED:
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Greg Si P.E. Direc r, Fernando Costa
Transpor t'on & Public Works Dept. Assistant City Manager
Jerry Parche' Consulting Engineers
ENGINEER
By: jilly'
Name• erry Parche, P.E.
Owner
1301 S. Bowen Road, Suite 300
Arlington, Texas 76013
APPROVED AS TO FORM AND LEGALITY:
Assistant City Attorney OFFICIAL RECORD
CITY SECRETARY
FT. WORTH, TX
City of Fort Worth,Texas
Amendment to Engineering Agreement
PMO Official Release Date:6.18.2010
Page 2 of 2
dPJerry Parche Consulting Engineers
March 30, 2011
Mr. Steve Eubanks, P.E.
Transportation & Public Works Dept.
Storm Water Management
City of Fort Worth
1000 Throckmorton Street
Fort Worth, Texas 76102
RE: JP No.08004;WARNER CHANNEL STUDY;
STUDY NO.SWS-011;REQUEST FOR CONTRACT AMENDMENT;
FORT WORTH,TEXAS
Dear Steve:
The Engineering Services Contract for a study of the Warner Channel Watershed and Floodplain was
executed on May 14,2009 between Jerry Parche' Consulting Engineers(JPCE)and the City of Fort Worth.
The project is entitled Warner Creek Open Channel Study, Study No. SWS-011.
A meeting was held on February 24,2011 to review the comments received on the interim hydrologic and
hydraulic study of existing conditions. As a result of discussions at that meeting, we are submitting this
request to your office for an amendment to our engineering contract for this project. This letter contains
information supporting our request.
Work on the project commenced with the`Kick Off meeting on June 2,2009. At that meeting,we received
our executed contract. At this time we are nearing completion of Tasks 3 and 4 of the Scope of Work for
this study. Following is a summary of key dates and events that have occurred during the project.
1. June 2, 2009- `Kick Off Meeting
2. August 27, 2009- Completed Survey of Cross Sections and Crossing Structures
3. December 7, 2009 - First Submittal of Watershed Hydrology-Task 3
4. January 25, 2010 - Received comments from Halff on first hydrology submittal
5. February 16, 2010 - Received 2009 Terrain Data from Halff
6. March 9, 2010 - Second submittal of Watershed Hydrology-Task 3
7. March 17, 2010 - E-mail from Halff on changes in routing method and use of a frequency
based hypothetical storm
8. October 22, 2010 - Resubmit hydrology and first submittal of Hydraulics -Task 4
9. December 3, 2010 - Hydraulic Review and Comments and Hydrology Review and Comments
received.
We request the City's consideration for additional fees on this project for services provided that were not
anticipated in the original contract. Following is a brief description of these services.
1301 S. Bowen Road, Suite 300 9 Arlington, Texas 76013 • Metro (817) 461-2433
Mr. Steve Eubanks,P.E. March 30,2011
JP No. 08004 Page 2 of 5
I. ADDITIONAL SERVICES
1 HYDROLOGIC MODELING-WATERSHED SUBDIVIDES
HEC-GeoHMS was utilized to subdivide the watershed. The process utilizes a DEM of the Warner
Channel Watershed created from the 2007 LIDAR Points. The software created numerous sub-
watersheds. The number of sub-watersheds was reduced to 16 using the GIS Editor. Hydrologic
characteristics were determined and input into the HEC-HMS model. Runoff hydrographs were
computed for each frequency storm studied. This model was presented in our first submittal on
December 7,2009.
The review comments received on the first submittal advised us there were still too many sub-
watersheds. We were directed to combine or adjust the limits of several sub-watersheds in order to
further reduce the number of subareas. This required redoing the HEC-GeoHMS model, re-
computing all sub-watershed parameters,revisingthe routing scheme,revisingthe HEC-MHS model
and rewriting the report.
2. WATERSHED PARAMETERS USING HEC-GEOHMS
Many of the watershed parameters initially determined using the HEC-GeoHMS software had to be
modified to more accurately model actual field conditions and to reduce the number of sub-
watersheds created by the software. Efforts were focused on using the HEC-GeoHMS software with
adjustments made using the GIS Editor for revisions in the Longest Flow Path for each sub-
watershed. However, it was found that adjustments made using the Editor may not be reflected in
basin characteristics determined using HEC-GeoHMS. After several unsuccessful attempts using
the HEC-GeoHMS software to prepare Longest Flow Path determinations after the sub-watersheds
generated by the software were modified,it was decided to use the GIS Editor alone to prepare these
values.
It seems that the HEC-GeoHMS software works better for really large watersheds. The size of the
Warner Channel watershed at Forest Park Blvd. is only 385 acres. As such some of the results in
using HEC-GeoHMS for this study required further investigation and analysis outside of the
software to obtain accurate results.
3. USE OF FREQUENCY BASED HYPOTHETICAL STORMS
On March 17, 2010, following the 2°d Hydrology submittal, we received an e-mail from Halff
directing us to incorporate two revisions in the methodology. The revisions included
A. Use of the Modified-Puls routing rather than the Muskingum-Cunge 8 pt. method.
B. Use of a frequency-based hypothetical storm using the depth-duration information provided in
the iSWM Manual for Tarrant County instead of the NCRS Type II distribution.
Revision`A'did not impact our services significantly since we had incorporated the Modified-Pulse
routing method into the watershed modeling. Since our hydrologic models were initially prepared
Mr. Steve Eubanks, P.E. March 30, 2011
JP No. 08004 Page 3 of 5
using the SCS Type II distribution, Revision `B' required redoing the HEC-HMS models for the
frequency-based Hypothetical Storm for all frequency storms studied.
4. NEW 2009 LIDAR POINTS
JPCE prepared a hydraulic model of Warner Channel using cross sections taken from a surface we
developed based on the 2007 Lidar Points initially received. This model was used to determine
storage-discharge relationships for input to the modified puls routing in the Warner Channel HEC-
HMS models submitted in December, 2009 and March, 2010.
On February 16,2010, we received the 2009 Lidar Points from Halff. Receiving new Lidar Points
required us to prepare a new surface and contours in GIS. A new hydraulic model of the stream was
then prepared. This model was used to update the storage-discharge values used for the modified
puls routing in the hydrologic model and determine new peak discharges for each frequency storm.
5. FOREST PARK BOULEVARD CULVERT ANALYSIS
In preparing the Engineering Services Contract and since starting work on the project, it has been
our understanding that the downstream limit of the Warner Channel study was considered to be the
upstream side of Forest Park Boulevard. As shown in Attachment E of the Engineering Services
Contract,the most downstream study cross section was taken on the upstream side of the roadway.
This cross section,the culvert section and the roadway were surveyed and the data used to prepare
a model of the roadway to generate water surface elevations on the upstream side of Forest Park
Boulevard. The assumptions incorporated into this model and the evaluation of these assumptions
were explained in the report and discussed at the review meeting on February 24, 2011.
However,due to comments we received on December 3,2010 on the first submittal of the hydraulic
study of existing conditions, JPCE performed additional services to further investigate the Forest
Park Boulevard culvert in response to Review Comments III.HEC-RAS Geometry,Comments 1 and
2 and IV.Flow Data,Comment 2 in the Hydraulic Review and Comments. These additional services
were discussed in the February 24, 2011 meeting and summarized in the minutes of this meeting.
As a result of the meeting discussions,the city reported that it was also their understanding that the
downstream end of the Warner Channel Study is at the upstream side of Forest Park Blvd. You
reported that the city expected an analysis of the culvert would be prepared, similar to the analysis
prepared by JPCE, to determine starting water surface elevations on the upstream side of this
roadway.
As such no further additional services for the analysis of the Forest Park Boulevard Culvert are
anticipated. Additional fees for the Forest Park Boulevard Culvert analysis included in this
amendment request are for services already provided.
6. FLOODWAY ANALYSIS
JPCE had not anticipated preparing a floodway in the study reach. This was due to several factors
Mr. Steve Eubanks, P.E. March 30, 2011
JP No. 08004 Page 4 of 5
including the large size of the channel compared to the flow and the developed condition of the areas
adjacent to the channel. However,Task 4 of the study scope requires preparation of a floodway if
there is a floodway on the existing FIRM.
The floodplain limits are mapped in the FIRM dated September 25, 2009 from Forest Park
Boulevard upstream to just south of the south end of Stanley Avenue. There does appear to be a
very narrow floodway within this reach shown on the FIRM. In response to this, since receiving
comments on the study on December 3,2010,JPCE has proceeded with services to investigate and
determine a floodway in the study reach.
These services included efforts to obtain a copy ofthe hydraulic model of Warner Creek(Stream CF-
3C per the FIRM). However, FEMA reported they could not locate the model. Other services by
JPCE to prepare a floodway were discussed at the February 24, 2011 meeting and summarized in
the minutes. However, Mr. Clair Davis, P.E., floodplain administrator, decided that a floodway
analysis is not necessary due to the physical characteristics of the channel and that the floodway
limits should be identified as coinciding with the floodplain limits.
As such no further additional services for determining a floodway are anticipated. Additional fees
for preparation of a floodway analysis included in this amendment request are for services already
provided.
U. REQUEST FOR ADJUSTED FEE
Fees for each Additional Service described above are given in Table 1.
TABLE 1: ADDITIONAL SERVICES&FEES
ADDITIONAL SERVICE FEE
1 $2,900
2 $1,640
3 $1,240
4 $1,640
5 $2,240
6 $1,940
TOTAL $11,600
Mr. Steve Eubanks, P.E. March 30, 2011
JP No. 08004 Page 5 of 5
Jerry Parche' Consulting Engineers requests an additional fee of $l 1,600.00 for the additional services
described above. We appreciate the City of Fort Worth's consideration of this request and will be happy to
discuss any alternatives the city may wish to explore. We will continue to expedite completion of the study.
Whatever the city's decision is in response to our request,the quality or timeliness of our services will not
be affected.
Thank you.
Sincerely,
i
Jerry arche', P.E.
JP:cp