Report Prepared by: Amber Minami, Engineering Project Manager
Title
SUBJECT: First Amendment to the Professional Services Agreement with HerSchy Environmental, Inc., in the Amount of $44,555.47 to Conduct Additional Laboratory Analysis of Groundwater Samples for Per- and Poly-Fluorinated Substances During the First Quarter 2023 at the Airport Hazardous Waste Site and Perform an Updated Sensitive Receptor Survey
REPORT IN BRIEF
Considers approving the First Amendment to Professional Services Agreement with HerSchy Environmental, Inc., to perform groundwater analysis and an updated Sensitive Receptor Survey in support of the Airport Hazardous Waste Site investigation. The amendment is necessary to ensure that the City of Merced remain in compliance with the Regional Water Quality Control Board (Regional Board) requirements.
RECOMMENDATION
City Council - Adopt a motion:
A. Approving the First Amendment to Professional Services Agreement with HerSchy Environmental, Inc. for additional groundwater sampling, laboratory analysis, and updated Sensitive Receptor Survey and the additional compensation in the amount of $44,555.47, for a total contract amount of $74,527.47; and,
B. Authorizing the City Manager or Deputy City Manager to execute the necessary documents.
Body
ALTERNATIVES
1. Approve, as recommended by staff; or,
2. Approve, subject to modifications as conditioned by City Council; or,
3. Refer to staff for reconsideration of specific items; or,
4. Deny.
AUTHORITY
Charter of the City of Merced, Article II Section 200 - Powers.
Merced Municipal Code, Title 3, Article III, Section 3.04.120 - Written Contract.
CITY COUNCIL PRIORITIES
As provided for in the 2022-23 Adopted Budget.
DISCUSSION
The site includes two areas, in close proximity, on the eastern edge of the Merced Airport near West Avenue. One area is a taxiway that was used as an engine warm-up area for crop dusters prior to take off. The soil alongside the taxiway is contaminated with pesticide blow-off from the crop dusters and is limited to shallow soils. In the autumn of 2002, the contaminated soils were capped by asphalt to prevent infiltration of rainwater and exposure to wind.
The second area is a former City of Merced Fire Department training area. This area was used by the Fire Department from the 1950's until about 1981 for training exercises which involved igniting and extinguishing flammable substances. All structures associated with the training exercises were removed in September 1999. The site is mostly paved to prevent any further infiltration of rainwater. The groundwater is contaminated with various solvents and hydrocarbons including tetrachloroethylene (PCE). PCE is the primary chemical of concern because it migrates readily through the soil and can persist in groundwater at low levels for long periods of time.
In November 2004, in attempt to perform groundwater remediation, the City of Merced authorized the injection a "fence" of hydrogen releasing compound to promote the natural degradation of contaminants. Remedial efforts have resulted in the reduction of contaminant concentrations at the site, but PCE concentrations remain in groundwater above water quality objectives. Regional Board staff have acknowledged that the contaminant concentrations have declined. As such, the groundwater sampling and reporting requirements have been reduced to offset costs associated with the project.
Presently, Regional Board staff believe that the areal spread of the contamination has been defined. The City of Merced and Regional Board staff are monitoring the plume to determine if additional remedial measures are necessary.
On June 21, 2022, the Regional Board issued a directive letter to the City to revise the Monitoring and Reporting Program (MRP) No. R5-2011-0808 to include Per- and Poly-Fluorinated Substances (PFAS) analysis in groundwater samples obtained during the third quarter 2022 monitoring event and complete a survey of sensitive receptors within one mile of the site. In an email dated July 25, 2022, Mr. Joseph Angulo, Deputy Director of Public Works, requested a six-month time extension to complete the sampling analysis due to procurement issues for the type of analysis requested.
In August 2022, HerSchy Environmental, Inc. was contracted to conduct sampling and reporting activities for the Airport Hazardous Waste Site for the 3-year period of July 2022 through June 2025.
Following procurement of a laboratory with the capability to perform analysis of the requested analytical suite, HerSchy Environmental, Inc. provided the City of Merced with the proposed modification to the scope of work.
Please be aware that, based on the analytical results, it may be necessary to add the analysis of PFAS to the monitoring program moving forward and install additional monitoring wells to delineate the extent of the contaminant groundwater plume. At such time, staff will come back to council for approval.
IMPACT ON CITY RESOURCES
Funding is available within the Fiscal Year 2022/23 adopted budget under account 557-1106-532-17-00 - Professional Services.
ATTACHMENTS
1. First Amendment to Professional Services Agreement
2. Agreement for Professional Services
3. Regional Water Quality Control Board Directive Letter
4. Email - Approval of Sampling Date Extension