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File #: 5122   
Type: Consent Status: Passed
File created: 11/5/2021 Department: County Administrative Office
On agenda: 11/16/2021 Final action: 11/16/2021
Subject: Amendment to Contract with Tetra Tech, Inc. for Chino Airport Groundwater Remediation Project
Attachments: 1. CON-CAO_11-16-21_Tetra Tech Amd No. 1 Chino Remediation, 2. Item #30 Executed BAI, 3. 18-144-A-1 Executed Contract





November 16, 2021



LEONARD X. HERNANDEZ, Chief Executive Officer, County Administrative Office

TERRY W. THOMPSON, Director, Real Estate Services Department




Amendment to Contract with Tetra Tech, Inc. for Chino Airport Groundwater Remediation Project





Approve Amendment No. 1 to Contract No. 18-144 with Tetra Tech, Inc., for professional services related to the Chino Airport Groundwater Remediation Project, increasing the contract amount by $2,871,200.76, from $3,510,540.63 to a total amount of $6,381,741.39, with no other changes to the contract or the contract term of April 1, 2018 through March 31, 2023.

(Presenter: Terry W. Thompson, Director, 387-5252)




Ensure Development of a Well-Planned, Balanced, and Sustainable County.

Provide for the Safety, Health and Social Service Needs of County Residents.



Approval of this item will not result in the use of additional Discretionary General Funding (Net County Cost).  To date, the Board of Supervisors (Board) approved $38 million in funding for expenses associated with the groundwater investigation and remedial project (Chino Airport Groundwater Remedial Project) located at the Chino Airport (7000 Merrill Avenue, Chino) (Airport), including $35 million in one-time funding, and $3 million in ongoing funding beginning in 2021-22.  Sufficient appropriation exists in the Chino Airport Groundwater Remedial Project (WBSE 10.10.0556) to fund the increased contract amount of $2,871,200.76.



On October 31, 1990, the Water Board issued Clean-up and Abatement Order No. 90-134 to the County for suspected contamination of groundwater beneath and near the Airport. The groundwater is suspected to have been contaminated due to past usage of volatile organic compounds (VOCs) by prior occupants of the Airport property. The County complied with this order by conducting activities at the Airport to identify potential sources of contamination: characterizing identified source areas and remediating discovered soil contamination within the confines of the Airport.


On February 12, 2002 (Item No. 43), the County awarded a contract to Tetra Tech, Inc. (Tetra Tech) for consultant services through a Request for Proposal (RFP) process. Under the contract, Tetra Tech prepared various work plans to investigate and characterize the soils and the groundwater contamination beneath the Airport. During 2003-04, this work included installation of groundwater monitoring wells and commencement of a groundwater sampling program to determine the extent of the groundwater contamination. In 2004-05, Tetra Tech investigated soils at the Airport and installed additional groundwater monitoring wells on the Airport property.


On October 17, 2006, (Item No. 16), the County awarded a new contract to Tetra Tech to continue the characterization work as the previous work identified the Airport property as a likely source of contamination. The contract with Tetra Tech allowed the County to maintain its project monitoring continuity and retention of a firm knowledgeable with the Water Board’s requirements.


The contract approved in 2006 was amended several times in order to increase the scope of work as Tetra Tech’s work helped the County understand the extent of groundwater contamination at and around the Airport property. For example, starting in 2007, Tetra Tech began investigation of possible groundwater contamination downgradient of the Airport property. In June 2008, the Regional Water Quality Control Board - Santa Ana Region (Water Board) issued Clean-up and Abatement Order No. R8-2008-0064, which required the County to conduct additional soils and groundwater investigations and develop remedial action plans for containment and mitigation of VOCs in groundwater downgradient of the Airport. The County has complied with this order with continuing assistance from Tetra Tech. Work by Tetra Tech to delineate the vertical and horizontal extent of the VOC impacts continued from 2008 through 2012. The impacts were documented by reports Tetra Tech submitted to the Water Board in December 2014 and April 2015. Based on this characterization and delineation work, Tetra Tech prepared for the County a Feasibility Study which was submitted timely to the Water Board pursuant to the 2008 Order on August 8, 2016.


On January 11, 2017, the Water Board issued Cleanup and Abatement Order (CAO) No. R8-2017-0011, which supersedes the previous order issued in 2008, and which continues the requirements for the County to complete the groundwater investigation and added a new reporting requirement.


As part of the investigation, Tetra Tech assisted the County in preparation of a Final Feasibility Study (May 2017) to identify and evaluate options to properly mitigate environmental impacts from past operations and historic activities at the Airport.  The result of the Final Feasibility Study was preparation of the Interim Remedial Action Plan (IRAP), which identifies the work required to remediate the VOCs found in groundwater. The purpose of the IRAP is to summarize the environmental conditions at the Airport and use technical data to explain the selection of the preferred remedial actions that will protect public health and the environment. The IRAP was developed as required by CAO No. R8-2017-0011.


On March 20, 2018 (Item No. 47), the Board approved Contract No. 18-144 in the amount of $3,510,540.63, for the period April 1, 2018 through March 31, 2023, to continue the provision of consulting services by Tetra Tech relating to the 2008 Water Board’s Cleanup and Abatement Order. 


Thereafter, the IRAP was approved by the Board on January 29, 2019 (Item No. 24), and after multiple reviews by the Water Board, the IRAP was submitted to the Water Board for final approval in May of 2020. The IRAP was approved by the Water Board on November 4, 2020.  Construction of the remediation infrastructure is estimated to begin January 2022 and continue through 2024.


Increased requirements relating to groundwater monitoring and investigation, and modifications to the project implementation resulted in costs being incurred at a higher rate during the contract period thus far.  Therefore, it is necessary to increase the contract amount for Contract No. 18-144 with Tetra Tech to continue with implementation of the project through the current expiration date of March 23, 2023.  Modifications to the project implementation include multiple revisions to site plans, designs, and specifications for the extraction wells, raw water conveyance piping, and communication equipment based on requests from private property owners, the Federal Aviation Administration and the State; the installation of additional monitoring wells to further define the groundwater contamination; necessary updates to the groundwater model; modifications to the preliminary design of the project; compliance with Department of Drinking Water 97-005 requirements; increased efforts to obtain permitting from outside agencies; increased requirements for groundwater monitoring and reporting; and additional investigative efforts required pursuant to approval of the IRAP, including the Human Health Ecological Risk Assessment.

Approval of the recommended Amendment No.1 with Tetra Tech will continue the services needed to proceed with the implementation of the Chino Airport Remedial Project. Completion of this work will meet the County goals to ensure development of a well-planned, balanced, and sustainable County as well as provide for the safety, health and social service needs of County residents.



In 2002, as a result of a competitive bid process, the County awarded an initial consultant agreement to Tetra Tech to investigate groundwater conditions at the Chino Airport. On October

17, 2006 (Item No. 16), the Board approved Contract No. 2006-1034 with Tetra Tech to perform additional investigation, required by the Water Board, to identify sources of pollution and to characterize the plume. The contract has been amended eight times, the last on December 20, 2016 (Item No. 9), for a total contract amount of $3,744,993.


A new, non-competitive Contract No. 18-144 was entered into with Tetra Tech on March 20, 2018 (Item No. 47), to provide consultant services relating to the Chino Airport Remedial Project for $3,510,540.63, for the period April 1, 2018 through March 31, 2023. Tetra Tech’s services are required because of its historical knowledge of the project and its ability to meet the required deadlines established by the Water Board.



This item has been reviewed by County Counsel (Agnes Cheng, Deputy County Counsel and Kristina Robb, Principal Assistant County Counsel, 387-5455) on October 12, 2021; Purchasing (Bruce Cole, Supervising Buyer, 387-2148) on October 18, 2021; Risk Management (Victor Tordesillas, Director, 386-8623) on October 18, 2021; Real Estate Services - Project Management (Kevin Ryan, Assistant Director, 387-5000) on October 15, 2021; Finance (Wen Mai, Principal Administrative Analyst, 387-4020 and Stephenie Shea, Administrative Analyst, 387-4919) on October 8, 2021; and County Finance and Administration (Robert Saldana, Deputy Executive Officer, 387-5423) on October 8, 2021.