Title
[Contract Amendment] Basin 151 and 153 Storm Drainage Master Plans
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FileID
File ID: 2026-01009
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Location
Location: District 2
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Recommendation
Recommendation: Pass a Motion authorizing the City Manager or designee to execute Contract Amendment No. 1 to City Agreement 2025-0554 with HDR Engineering, Inc. to convert the existing XPSWMM storm drainage model to a multi-dimensional hybrid model within the FY24 DOU Operating Grant Program (G14240100, Fund 6211), for an amount not to exceed $143,566, bringing the agreement’s total not-to-exceed amount to $393,188.11, and extend the contract services through December 31, 2026.
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Contact
Contact: Gary Gulseth, Project Manager, (916) 808-1415, ggulseth@cityofsacramento.org; Sherill Huun, Engineering & Water Resources Division Manager, (916) 808-1455, shuun@cityofsacramento.org; Dalia Fadl, Director, (916) 808-3765, dfadl@cityofsacramento.org; Department of Utilities
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Presenter
Presenter: None
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Attachments
Attachments:
1-Description/Analysis
2-Contract Amendment
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Description/Analysis
IssueDetail
Issue Detail: Staff recommends City Council approve Contract Amendment No. 1 with HDR Engineering, Inc. to convert the existing one-dimensional (1D) XPSWMM hydraulic storm drainage model for Basins 151 and 153 to a multi-dimensional (1D/2D) hybrid model. The consultant will use the improved model to identify hydraulic deficiencies in the existing drainage system and evaluate remedial alternatives that will bring the system into compliance with public safety and flood performance standards. The proposed 1D/2D hybrid model will simulate rainfall runoff over the complex two-dimensional surface of the basins. This process will provide better insight into flow patterns and flood accumulation and, thus, allow HDR Engineering, Inc. and staff to better identify, and likely reduce, the need and level of improvement alternatives.
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PolicyConsiderations
Policy Considerations: The proposed contract amendment exceeds the City Manager’s approval authority, requiring Council approval per City Code 3.04.020.
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EconomicImpacts
Economic Impacts: None.
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EnvironmentalConsiderations
Environmental Considerations: Per the California Environmental Quality Act (CEQA) Guidelines Section 15061(b)(3), approval of the proposed contract amendment is exempt from the CEQA, under the general rule that CEQA only applies to actions with potential to significantly affect the environment. Approval of this contract amendment for additional engineering services will not affect the environment. The modeling and master planning activities are exempt from CEQA pursuant to CEQA Guidelines Section 15306, (Information Collection) which consists of basic data collection, research, experimental management, and resource evaluation activities that do not result in a serious or major disturbance to an environmental resource.
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Sustainability
Sustainability: The proposed project is consistent with Goals PFS-3.1 and PFS-A.4 in the 2040 General Plan as it improves infrastructure reliability and implements a stormwater master plan program to guide improvements and ensure that the drainage system meets intended levels of service.
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Commission/Committee Action
Commission/Committee Action: Not applicable.
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RationaleforRecommendation
Rationale for Recommendation: Conversion of the existing 1D hydraulic model to a 1D/2D hybrid model will provide better insight into the complex flow patterns and flood accumulation within the basins and, thus, allow HDR Engineering, Inc. and staff to better identify, and likely reduce, the need and level of potential remedial alternatives in the final master plan. The result, combined with the results of other master plans performed for basins in the drainage system, will allow staff to better plan and prioritize future capital improvement projects and funding.
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FinancialConsiderations
Financial Considerations: The original not-to-exceed amount of the agreement was $249,622.11. The proposed Contract Amendment No. 1, in the amount of $143,566, would increase the agreement’s total not-to-exceed amount to $393,188.11. Sufficient funds are available within the FY24 DOU Operating Grant Program (G14240100, Fund 6211) to execute the agreement. The City funds will be reimbursed through the Sacramento Area Council of Governments (SACOG) Green-Means-Go grant upon completion of the master plan.
There are no General Funds allocated or planned for this project.
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LocalBusinessEnterprise
Local Business Enterprise (LBE): Contractor is an LBE.
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Background
Background: Drainage master planning is an important tool to help staff better understand the hydraulic and operational deficiencies within a basin so that maintenance and capital project funds are more effectively utilized. The Department of Utilities (DOU) maintains over 140 drainage basins. Master plans have been completed for 53 of the basins. Of the completed 53 basins, only five master plans are current, having been completed in the past 10 years. The remaining basins have been categorized and ranked based primarily on the historical type and number of “trouble calls” during past severe rain events. The ranking also considered public safety, property damage, street flooding, development, and environmental issues. Basins 151 and 153 ranked high and, thus, were selected for master planning.
In April 1992, a skeletonized hydraulic model and master plan for Basin 153 was completed by Kennedy/Jenks Consultants. In April 1996, a similar hydraulic model and master plan for Basin 151 was completed by West Yost Associates. Finally, in July 2024, a FEMA Letter of Map Revision (LOMR) hydraulic model was developed by MRPE, Inc., based on FEMA criteria and a 100-year/24-hour storm. Since completion of the 1992 and 1996 master plans, there have been several significant developments that have impacted the hydraulics within the basins, and hydraulic and operational requirements have evolved, making the master plans obsolete. The 2024 FEMA model does not address or include City performance standards for master planning. Therefore, in June 2025, HDR Engineering, Inc., was selected using an on-call agreement to expand and update the 2024 model to City drainage standards (10- and 100-year frequency, 24-hour duration design storms) and prepare a new/updated master plan. Following the initial modeling process and during initial preparation of the master plan, it became apparent that additional detail was required to properly identify the need, location and level of potential remedial alternatives. To provide better insight into flow patterns and flood accumulation and, thus, better identify, and likely reduce, the need and level of remedial alternatives, staff requested HDR Engineering, Inc., to provide a proposal to convert the existing XPSWMM model to a 1D/2D hybrid model. The results will then be used to revise the initial master planning work performed and to complete the final report.
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