City Of Palo Alto: Matadero Creek/VA Palo Alto Health Care Diesel Spill Community Update

Press release from the City of Palo Alto:

November 10, 2021

Nov. 10, 2021 Community Update

The Fire Department considers the incident at Matadero Creek to be in its final stages of remediation. The Palo Alto Fire Department remains in Unified Command, which means the Palo Alto Fire Department Hazmat Bureau is working as a cohesive unit through all phases of this incident with the VA Palo Alto Health Care System, City of Palo Alto Stormwater staff, California Department of Fish and Wildlife, the San Francisco Regional Water Board, the Santa Clara Valley Water District and third-party remediation and environmental scientist experts.

Representatives from regulatory agencies continue to meet to review all aspects of the incident. Creek monitoring data indicates that Matadero Creek is largely remediated with no observed impacts to fish or wildlife. The boom network remained in place for the first rains of the season as a precaution. Following those first rains there was no diesel residual observed on the boom network, and the booms appeared to be impeding the natural flow of the creek. Therefore the boom network was removed on Friday, Nov. 5, 2021.

Due to diesel residual measured in the soil at the storm drain outfall, the VA obtained a permit from Fish and Wildlife to remove a limited amount of soil at the outfall. The soil removal was completed on Oct. 19, along with follow-up sampling at the creek bank. Sand bags were placed on the site as a temporary measure to protect the creek bank through the winter. A long-term plan to shore up the creek bank will be presented to the Department of Fish and Wildlife for review and approval. It is expected that the sand bags will remain in place throughout the 2021-2022 rainy season and that the final creek bank shoring will be installed in the late spring or early summer.

At the creek bank near water sampling site W-007, bioremediation additives were applied Sept. 28, to enhance natural microbial breakdown of the remaining petroleum. The objective was for the application to be in place for about a month to accelerate natural processes and maximize removal prior to a significant rain event while minimizing disturbance of the creek bank and vegetation. Contractors had planned to resample the soil at the end of October, but the first fall rain event took place the weekend of Oct. 23-24. This raised water levels about 18 to 24 inches and covered this previously exposed creek bed. City staff from Public Works and Fire inspected the area multiple times during the rain event; there was no evidence of diesel residual be transported from the soil to the creek. Additional soil sampling will be initiated when the water levels recede.

Per the past press releases, throughout the remediation, Matadero Creek has been monitored at 16 locations for multiple chemicals related to diesel. The monitoring will continue during the rainy season but the frequency will be reduced following discussions with Fish and Wildlife. Thus far it appears that the results remain below the Water Board goals.

All data are available by downloading the latest data table.

Download: Creek Water Sampling Table 1 and 2 With Map as of November 10, 2021(PDF, 1MB)

More information will be released as details become available.

Read the initial joint community update on this issue.

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This press release was produced by the City of Palo Alto. The views expressed here are the author’s own.