Agenda Item AGENDA STAFF REPORT ASR Control 25-000949
MEETING DATE:	03/24/26
legal entity taking action:	Board of Supervisors and Orange County Flood Control District
board of supervisors district(s):	All Districts
SUBMITTING Agency/Department:	OC Public Works (Approved)
Department contact person(s):	Justin Golliher (714) 667-1675
	Alison Camara (714) 647-3961

Subject: Approve Contract to Update the Orange County Hydrology Manual

ceo CONCUR

County Counsel Review

Clerk of the Board

Concur

Approved Agreement to Form

Discussion

3 Votes Board Majority

Budgeted: Yes

Current Year Cost: $850,000

Annual Cost: FY 2026-27 $700,000
FY 2027-28 $122,150

Staffing Impact:

# of Positions:

Sole Source: No

Current Fiscal Year Revenue: N/A

Funding Source: Fund 115: 50%, Fund 400: 50%	County Audit in last 3 years: No
Levine Act Review Completed: Yes

Prior Board Action: N/A

RECOMMENDED ACTION(S):

Authorize the County Procurement Officer or Deputized designee to execute a contract with Pacific Advanced Civil Engineering, Inc. for Consultant Services to Update the Orange County Hydrology Manual, in an amount not to exceed $1,672,150, effective for a three-year term upon Board of Supervisors approval.

SUMMARY:

Award of a contract for Consultant Services to Update the Orange County Hydrology Manual will provide updated computational criteria for estimating runoff, discharge and volume, enabling the County of Orange and Orange County Flood Control District to consistently and accurately size flood control facilities and improve public safety within Orange County.

BACKGROUND INFORMATION:

The Orange County Flood Control District (District) and the County of Orange (County) have jurisdiction over 380 miles of flood conveyance facilities, more than 35 regional detention basins and dams and over 340 miles of County roadways. The 1986 Orange County Hydrology Manual and 1996 Orange County Hydrology Manual Addendum No. 1 (Manual) provides important computational criteria used for estimating runoff, discharge and volume used to size flood control facilities throughout Orange County. This information supports the County and District’s ability to prioritize flood control capital improvement projects and provides critical technical guidance for the planning, design and development of these facilities.

An update to the Manual is now necessary to evaluate and modernize hydrologic procedures, reassess runoff frequencies using more than 40 years of new data since the original calibration in 1983 and incorporate considerations related to climate change, post-fire hydrology and advancements in hydrologic modeling software.

On May 20, 2025, OC Public Works issued a Request for Proposal (RFP) for Consultant Services to Update the Orange County Hydrology Manual (Services). The RFP was advertised on the County online bidding system. Two proposals were received and deemed responsive. The evaluation panel, composed of members from OC Public Works and a subject matter expert from the public, scored the responsive proposals. See Attachment D for the Summary of Evaluators' Scoring. The resulting rankings are as follows:

Contractors	Rank
Pacific Advanced Civil Engineering, Inc.	1
AtkinsRealis USA Inc.	2

The Orange County Preference Policy (OCPP) was applicable and incorporated into this solicitation, however no OCPP qualified proposals were submitted.

OC Public Works is recommending the Board of Supervisors (Board) approve Contract MA-080-26010792 (Contract) with Pacific Advanced Civil Engineering, Inc. (Contractor) for Services, in an amount not to exceed $1,672,150, effective for a three-year term upon Board approval.

An analysis was completed to verify the Contract provides County with persons specially trained, experienced, expert and competent to perform the special services in accordance with the law. The professional license numbers were verified as current and active through the Department of Consumer Affairs database on December 23, 2025. A copy of the verification is on file.

OC Public Works has conducted due diligence on the Contractor. Reference checks were satisfactory and completed with Ventura County and the cities of Stanton and Palmdale regarding similar projects.

The Contract includes a subcontractor. See Attachment B for information regarding the subcontractor and Contract Summary Form.

Compliance with CEQA: This action is not a project within the meaning of the CEQA Guidelines Section 15378 and is therefore not subject to CEQA, since it does not have the potential for resulting in either a direct physical change in the environment, or a reasonably foreseeable indirect physical change in the environment. The approval of this agenda item does not commit the County to a definite course of action in regard to a project since it is an approval of a contract for Services to update the Manual. This proposed activity is therefore not subject to CEQA. Any future action connected to this approval that constitutes a project will be reviewed for compliance with CEQA.

FINANCIAL IMPACT:

Appropriations for this Contract are included in the FY 2025-26 Budget and will be included in the budgeting process for future years for the following funds.

Fund 115, OC Road	50%
Fund 400, OC Flood	50%

The proposed Contract is contingent upon funding availability. In the event funding is reduced or terminated, the County may renegotiate the level of services and/or terminate the Contract without penalty.

STAFFING IMPACT:

N/A

ATTACHMENT(S):

Attachment A - Contract MA-080-26010792 with Pacific Advanced Civil Engineering, Inc.
Attachment B - Contract Summary Form
Attachment C - Memorandum of Recommendation
Attachment D - Summary of Evaluators Scoring
Attachment E - Individual and Written Scoring Sheets