City Council
259 N. Wilma Avenue
Ripon, CA 95366
MEMO
To: Honorable City Council
From: James Pease, Public Works Director
Date: 06/14/2022
Subject: Wood Rodgers, Inc.
RECOMMENDED ACTION:
Approve and authorize the Mayor to sign Amendment No. 2 with Wood Rodgers, Inc. in the not to exceed amount of $25,761 for additional work in preparing the operation and monitoring plan, testing and sampling in order to operate Well 12, as requested by the State Regional Water Quality Control Board (funding source: Water Enterprise Operating Fund).
BACKGROUND/DISCUSSION:
As part of the Well 5 & 12 Rehabilitation project, Well 12 was modified to completely seal off the upper aquifer of the well to eliminate the contamination of nitrates into the well and lower aquifer. The majority of the City’s drinking water is obtained from these lower aquifers, which offer clean water meeting the State drinking water standards. Although post testing has shown a decrease in nitrates to Well 12 since the modification was completed, the levels are still not suitable to use the well for potable drinking water.
The high nitrate levels at the Well 12 location are a result of fertilizer storage at a nearby facility, which is no longer in service. The Regional Water Quality Control Board (RWQCB) oversees the contamination and cleanup efforts of the nitrate plume that are the responsibility of the previous facility owner.
Although Well 12 is not suitable for potable drinking water, the production rate substantially increases the redundancy of the City non-potable water system. A service agreement was entered into with Wood Rodgers, Inc. in 2017 to provide a hydrogeologic assessment to determine whether the operation of Well 12 would have a migration impact on the nitrate plume.
Once feasibility was determined, contract amendment No. 1 was entered into with Wood Rodgers, Inc. in 2019 to prepare an operations plan that identifies the Well 12 pumping rate along with an analysis showing how that rate will have negligible impact on the nitrate plume and ongoing clean-up efforts. Additionally, the RWQCB requested a monitoring and reporting plan that would be followed while Well 12 is being used to confirm the pumping does not impact the nitrate plume.
Well 12 pumping operations began in March of 2020 for use in the City non-potable system and has provided between 500 and 750 gallons per minute when activated since that time. The pumping rate and analytical results have been monitored by Wood Rodgers, Inc. with concurrence from the RWQCB that no migration impact to the nitrate plume has occurred.
The operation and monitoring plan went through several revisions before approval by the RWQCB and additional cycle testing and water quality sampling over the past two years of operating Well 12 has increased the cost incurred by Wood Rodgers, Inc. and is described in detail in the attached contract amendment.
Moving forward the last reporting period for the approved plan is scheduled for the 3rd quarter of 2022. Wood Rodgers, Inc. will continue to monitor and analyze the pumping results of Well 12 and report those finding to the RWQCB. City staff will be working with the RWQCB to determine the required path necessary to continue pumping Well 12 beyond 2022.
FISCAL IMPACT:
The attached Contract Amendment No. 2 with Wood Rodgers, Inc. includes a detailed description of the additional tasks required by the RWQCB in order to operate Well 12. The cost to complete the work is for a not-to-exceed amount of $25,761, which will be funded through the Water Enterprise Operating Fund.
Attachments:
1. Contract Amendment No. 2