Item 4F-4G Item 4F and Item 4G
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M E M O R A N D U M
(May 17, 2023)
To: Shana Yelverton, City Manager
From: Rob Cohen, Director of Public Works
Subject: Item 4F: Approve an engineering services agreement with
Freese and Nichols, Inc. (FNI) to provide engineering services
to update the City’s water model and master plan in an amount
not to exceed $202,400.
Item 4G: Approve an engineering services agreement with
Freese and Nichols, Inc. (FNI) to provide engineering services
to update the City’s Denton Creek/Grapevine Lake wastewater
model and master plan in an amount not to exceed $169,800.
Action
Requested: Item 4F: Approve an engineering services agreement with Freese
and Nichols, Inc. (FNI) to provide engineering services to update the
City’s water model and master plan in an amount not to exceed
$202,400.
Item 4G: Approve an engineering services agreement with Freese
and Nichols, Inc. (FNI) to provide engineering services to update the
City’s Denton Creek/Grapevine Lake wastewater model and master
plan in an amount not to exceed $169,800.
Background
Information: The purpose of items 4F-4G is to approve engineering services
agreements with FNI to update the City’s water and wastewater
models and master plans.
As required by charter, the City of Southlake updates certain
master plan documents every four years. The last comprehensive
update to the City’s water model was performed in 2012, including
modeling and analysis to identify needed improvements for current
and future capacity. The last comprehensive update to the City’s
wastewater model was performed in 2009, identifying needed
improvements for current and future capacity. Recommendations
from both updates were adopted into the City’s Southlake 2030
plan in 2012. Subsequent master plan updates have taken a more
focused approach but have not reviewed system modifications or
addressed the change in demand and demographics of the
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previous ten years. In 2021, Public Works and Planning &
Development Services began preparations for a master plan
update to review and reprioritize projects remaining on the master
plan. During this process, several questions and information
shaped the basis for the evaluation of updated studies and
modeling to inform plan recommendations. Updates to the water
model requires specialized software and system monitoring
equipment, resulting in the City Staff to engage an engineering
consultant to assist in the master plan revisions.
Water
Due to the interdependency of the elements of the water system, an
update to the complete model will be necessary. Current knowledge
of the water system is largely based on the 2012 study, of which
many concerns have been raised by engineering and operations.
Other more focused studies have been performed since (2017 Water
Quality Study, 2014 & 2019 Water Conservation Plan, 2021 AWIA
Risk and Resiliency Assessment (AWIA) and 2022 Texas Senate Bill
3 (SB3) Emergency Preparedness Plan). These studies focused on
delivery optimization, water quality, conservation, risk reduction,
system redundancy and emergency preparedness.
The water update will address these concerns and verify
recommendations from the most recent studies by building a
complete water model, calibrate the model based on field-verified
pressure and flow readings, review remaining 2030 CIP projects, and
recommend new CIP projects for implementation. The following
highlights major scope items for the water update. Existing and future
conditions are considered for performance and recommended
improvements. AWIA/SB3 items requiring the study from the model
update are noted:
• Water demand projections
• All pipes water model rebuild and calibration
• Average, max, fire flow and regulatory demand analysis (SB3)
• Pressure plane analysis and delineation (SB3)
• System improvement analysis and alternatives
• Water age modeling (AWIA)
• Source trace modeling (AWIA)
• Alternate feed to high pressure plane from TW King Pump
Station (SB3)
• Updated CIP project costs and phasing recommendations
Wastewater
Unlike the City’s water system, the wastewater system contains sub-
basins that operate independently from each other. The most recent
Wastewater Master Plan was adopted in 2012 and utilized modeling
from 2009 that identified needed improvements for current and future
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capacity. Since that time the City has conducted flow monitoring with
the Town of Westlake for the N-1 interceptor in 2016, and flow
monitoring along with smoke and dye testing in 2017 - 2018.
The majority of growth within the wastewater system since 2009 has
occurred in the Denton Creek/Grapevine Lake watershed, identified
as the North Service Area. Near-term growth is also anticipated to
remain concentrated in the North Service Area. Coupled with its
dependency upon lift stations for final conveyance for treatment, it
has been identified as requiring a comprehensive update.
Similar to the water update, the wastewater master plan process will
update the future flow projections, update the hydraulic wastewater
model, and provide an updated Capital Improvements Plan (CIP) for
the North Service Area, including a review of current CIP project
recommendations. The existing model from 2009 includes all 10-inch
and larger wastewater mains and limited 8-inch mains, accounting
for some 40% of the 2009 infrastructure. The revised model will map
and evaluate all wastewater mains within the North Service Area.
The following highlights major scope items for the North Service Area
wastewater update. Existing and future demands are considered for
performance and recommended improvements. AWIA/SB3 items
are noted:
• Wastewater demand projections (existing and future)
• All pipes wastewater model rebuild
• Sub-basin remapping
• Dry and wet weather calibration and modeling
• Performance analysis
• System improvement analysis and alternatives
• Lift station assessment (AWIA/SB3)
• Updated CIP project costs and phasing recommendations
Model and Master Plan Updates
As the City approaches its ultimate buildout conditions, projects will
be identified that will help the City to direct resources toward
correcting issues with current capacity and building out our system
to manage remaining growth. Recommendations from the City’s Risk
and Resiliency Assessment and Emergency Preparedness Plan will
be analyzed to confirm feasibility and project elements are
incorporated into the CIP. The master plan updates will focus more
on operational optimization, water quality measures, and long-term
sustainability rather than growth or facility expansion drivers.
Financial
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Considerations: Funding for this agreement is budgeted as part of the approved
Capital Improvement Program. This agreement is within the project
budget.
Strategic Link: These items link to the City’s Strategy Map by delivering on the focus
area of Infrastructure & Development. It provides this by focusing on
Financial Objective F2: Investing to Provide & Maintain High Quality
Public Assets.
Citizen Input/
Board Review: None.
Legal
Review: The proposed agreement is a standard agreement that the City
Attorney has reviewed and approved.
Alternatives: The City Council may approve or deny the agreement.
Supporting
Documents: Attachment A: Water Master Plan Modeling Memo
Attachment B: Wastewater Master Plan Modeling Memo
Attachment C: Water Agreement
Attachment D: Wastewater Agreement
Staff
Recommendation: Item 4F: Approve an engineering services agreement with Freese
and Nichols, Inc. (FNI) to provide engineering services to update the
City’s water model and master plan in an amount not to exceed
$202,400.
Item 4G: Approve an engineering services agreement with Freese
and Nichols, Inc. (FNI) to provide engineering services to update the
City’s Denton Creek/Grapevine Lake wastewater model and master
plan in an amount not to exceed $169,800.
Staff
Contact: Rob Cohen, P.E., Director of Public Works
Lauren LeNeave, Deputy Director of Public Works - Administration
Jeff Ginn, P.E., Deputy City Engineer