CM-2015-692 - 2/27/2015City of Round Rock
R......
IK Agenda Item Summary
Agenda Number:
Title: Consider executing Supplemental Contract No. 1 with Halff Associates,
Inc. for the Chisholm Valley Drainage Modeling Project.
Type: City Manager Item
Governing Body: City Manager Approval
Agenda Date: 2/27/2015
Dept Director: Michael Thane, Director of Utilities and Environmental Services
Cost: $11,612.00
Indexes: Regional Detention Fund
Attachments: LAF_SC#1Halff _ChisholmValleyDrainage_CM2.27.15,
SC#1 _Halff__ChisholmValleyDrainage_CM2.27.15,
Map_Ch isValAreaExhibit
Department: Utilities and Environmental Services
Text of Legislative File CM -2015-692
The City previously entered into an Engineering Services Contract with Halff Associates,
Inc. to analyze the tributaries of Lake Creek within the Chisholm Valley residential
neighborhood to determine flood risk and to explore solutions that could be implemented by
the City to reduce such risk.
This Supplemental Contract No. 1 addresses the tributary that runs west to east through the
neighborhood from Frontier Park to just north of Purple Sage Drive. This contract will:
-Update the previous hydrologic and hydraulic modeling performed by Halff in response to
new data from the Upper Brushy Creek Water Control and Improvement District Watershed
Study.
-Better quantify the storm water flows originating at the upper end of the tributary in and
around the La Frontera development.
-If updated modeling continues to demonstrate areas of concern, will assist the City with
identifying the most feasible alternative for reducing flood risk given existing available land
constraints.
This Supplemental Contract No. 1 increases the original contract by $11,612 to a total of
$31,056.08.
Staff recommends approval.
CxyefRoune Rack POOH PH.W OnY 015
LEGAL DEPARTMENT APPROVAL FOR CITY COUNCILICITY MANAGER ACTION
Required for Submission of ALL City Council and City Manager Items
Department Name: utllllles & Emlroomental Services Project Name: Chisholm Valley Drainage Mwelirp
Project MgrlResource: Lance Shallenberger
Council Action:
ORDINANCE
❑ City Manager Approval
ttorney
ContractorNendor: Heta Associates, Inc
RESOLUTION
CMA Wording
Consider executing Supplemental Contract No. 1 vnih Half Associates, Inc. for the Chisholm Valley Drainaga Modeling project.
Date
S�
OAwdoxlSCClnts10199114081MISC100329791.XLS Updated 6/3/08
STATE OF TEXAS
COUNTY OF WILLIAMSON
SUPPLEMENTAL CONTRACT NO. 1
TO CONTRACT FOR ENGINEERING SERVICES
FIRM: HALFF ASSOCIATES, INC. ("Engineer")
ADDRESS: 4030 West Braker Lane, Suite 450, Austin, TX 78759-5356
PROJECT: Chisholm Valley Drainage Modeling
This Supplemental Contract No. 1 to Contract for Engineering Services is made by and between
the City of Round Rock, Texas, hereinafter called the "City" acid Halff Associates, Inc.,
hereinafter called the "Engineer'.
WHEREAS, the City and Engineer executed a Contract for Engineering Services, hereinafter
called the "Contract", on the 25th day of January, 2014 for the Chisholm Valley Drainage
Modeling Project in the amount of $19,444.08; and
WHEREAS, it has become necessary to amend the Contract to modify the provisions for tine
scope of services and to increase the compensation by $11,612.00 to a total of $31,056.08;
NOW THEREFORE, premises considered, the City and the Engineer agree that said Contract
is amended as follows:
Article 2. Engineering Services and Exhibit B. Engineering eering Services shall be amended as set
forth in the attached Addendum To Exhibit B. Exhibit C. Work Schedule shall be amended as
set forth in the attached Addendum To Exhibit C.
Il.
Article 4. Compensation and Exhibit D. Fee Schedule shall be amended by increasing by
$11,612.00 the lump sum amount payable under the Contract for a total of $31,056.08, as shown
by the attached Addendum to Exhibit D.
IN WITNESS WHEREOF, the City and the Engineer have executed this Supplemental
Contract in duplicate.
supplemrnml Caavcl Rev.12101108
0199.1408;00329132 84215
P -M -0o6 -tea,
HALFF ASSOCIATES, INC.
By:
tifvLi
ita i
ZE
Date
CITY OF UND ROC APP O ED S TO ORM:
By: a
p , 9ayo LQUne �} �� Stepha L. Sheets, City Attorney
C3B
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Date
supplemaftl CONmd Rcv.12/01/08
0199.1408;00329732 84275
ADDENDUM TO EXHIBIT B
Engineering Services
Exhibit E in the original contract between the City of Round Rock and Halff Associates, Inc. dated
January 25, 2014 shall be amended as delineated below.
1. Add the following at the end of Section 1.1 Existing Models and Dala:
• Collect and review drainage plans and topographic Wraps in and around the
La Froutera development for the areas that contribute storm water to the
tributary that begins just south of Yucca Drive and continues west to
Frontier Park (hereinafter "Lake Creek Tributary 6-A").
• Obtain any updates to the WCID hydrologic models that have become
available tip to the date of commencement of the additional services
described herein under 2 below.
2. Add the following at the end of Section 2.1 hydrologic Models The follou,iutg
models will be developed for the 2 10 25 50 100 500 Uhintale 25 and Ultimate
100 year events:
• Amend the described hydrologic models as appropriate based on any
updates to the WCID hydrologic models that have been obtained.
• Analyze acrd verify the storm water flows from La Frontera and other areas
contributing to the upstream end of Lake Creek Tributary 6-A.
Explore other solutions, or refinements to Proposed Conditions 3 above,
that could be effective and efficient to attenuate or reduce flooding along
Lake Creek Tributary 6-A and develop associated modeling; such
solutions may, include but not be limited to: sizing a smaller pond in the
vicinity of Frontier Park; sizing a smaller pond in the vicinity of Frontier
Park in conjunction with downstream culvert and/or channel
improvements; or incorporating the existing detention pond near
Bluebonnet Elementary School into the proposed detention pond near
Frontier Park.
3. Add the following at the end of Section 2.2 Hydraulic Alodels. The following nnodels
twill be developed for the 2. 10 25 50. 100. 500 Ultimate 25 and Ultimate 100 Year
evenls:
• Amend the associated hydraulic models as appropriate based on any
updates to the hydrologic models that have been made.
• Develop corresponding hydraulic models as appropriate for the
solutions or refinements discussed at the end of Section 2.1 above.
ADDENDUM TO EXHIBIT C
Work Schedule
All Engineering Services to be provided tinder the Contract shall be satisfactorily completed by the
Engineer on or before March 31, 2015.
Addendum to Exhibit D
Fee Schedule
Delete in entirety the Fee Schedule contained in Exhibit D of the original contract between the City of Round
Rock and Halff Associates, Inc. dated January 25, 2014 and replace with the following:
Task
Total
Labor
Hours
TotalOther
Loaded
Labor Cos[
Direct
Costs
Sub -
consultants
TOTALS
Original Contract
1.0 Data Collection
1.1 Existing Models and Data
14
$1,527.10
$0,00
$0.00
$1,527.10
1.2 Field Topographic Survey
15
$1,899.16
1 $0.001
$0.001
$1,899.16
2.0 Modeling
2.1 Hydrologic Models
46
$5,034.18
$0.00
$0.00
$5,034.18
2.2 Hydraulic Models
46
$5,034.18
$0.00
$0.00
$5,034.18
3.0 Reporting
3.1 Engineers Report
34
$3,578.561
$450.00
$0.00
$4,028.56
3.2 Estimates of Probable Cost
14
$1,920.90
$0.00
$O.OD
$1,920.90
Subtotal:
169
$18,994.08
$450.00
$0.00
$19,444.08
Supplemental Agreement No.1
1.0 Data Collection
1.1 Existing Models and Data
3
$360.00
$0.00
$0.00
$360.00
2.0 Modeling
2.1 Hydrologic Models
29
$3,686.50
$0.00
$0.00
$3,686.50
2.2 Hydraulic Models
31
$4,058.50 1
$0.00 1
$0,001
$4,058.50
3.0 Reporting
3.1 Engineers Report
20
$2,441.00
$0.00
$0.00
$2,441.00
3.2 Estimates of Probable Cost
9
$1,066.00 1
$0.001
$0.001
$1,066.00
Subtotal:
91
$11,612.001
$0.001
$0.001
11,612.00
AMMENDED GRAND TOTAL:
260
$30,606.08 1
$450.00 1
$0.00
$31,056.08