VA Diesel Spill Community Updates

Summary

The Palo Alto Fire Department considers the diesel remediation effort at Matadero Creek to be nearing the end. At this time, it appears that the site was successfully remediated prior to the commencement of the rainy season, with no observable ecosystem impact, ending the largest hazardous material release to surface waters that City staff have ever managed.

Throughout the incident, the Palo Alto Fire Department Hazmat Bureau worked as a cohesive unit 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 experts and environmental scientists. Representatives from regulatory agencies continue to meet at a reduced frequency to continue observations and communication throughout the rainy season, and to close out the last portion of the remediation effort.

The water quality monitoring along Matadero Creek has continued during the rainy season but at a reduced frequency and at a limited number of locations, following discussions with Fish and Wildlife. Thus far the results remain well below the Water Board goals.

The last remaining task along the creek is at the storm drain outfall and the surrounding creek bank. Prior to the first rains, the area was underlain by visqueen and temporarily secured by absorbent bags. Sandbags were placed on the site as a temporary measure to protect the creek bank through the winter. The VA will prepare a long-term plan to shore up the creek bank and present it to the Department of Fish and Wildlife for review and approval. It is expected that the sandbags will remain in place throughout the 2021-22 rainy season and that the final creek bank shoring will be installed in the late spring or early summer.

The City is working with the VA to close the City-issued hazmat permits. Efforts are now underway to improve communication between the VA and the City and develop a strategy to prevent or minimize future incidents.

Creek Data and Map Update

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, 497KB)

More information will be released as details become available.

Read the initial joint community update on this issue.

Summary

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.

Storm Drain Outfall and Creek Bank Update

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.

On-going Creek Monitoring

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.

Download: (PDF, 1MB)Creek Water Sampling Table 1 and 2 With Map as of November 10, 2021(PDF, 497KB)

Summary

The Fire Department continues to consider the incident at Matadero Creek to be stable. Soil remediation continues on the VA property, while regular monitoring of the creek at 16 locations indicates that Matadero Creek is largely remediated, with no observed impacts to fish or wildlife. The sampling data continue to show that the boom system is still keeping the residual contained. All work is being conducted to ensure that wildlife remain protected throughout the 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, including cause of the release, continued containment of the diesel, and remediation of the soil and water. Action plans continue to evolve based on monitoring results and expert recommendations.

On Oct. 19, contaminated soil was removed at the outfall. In addition, Unified Command, the VA, and third-party contractors developed a monitoring plan for the October rains.

Soil Remediation Update

Soil remediation is ongoing at two locations along the creek--next to the outfall and at the creek bank near the water sampling site W-007.

In August, soil samples were collected at the outfall in tandem with the storm drain sampling. Four of 12 samples contained TPH-Diesel at concentrations above the Water Board goal of 260 mg/kg (ranging from 290 to 3,300, with an average of 1,235 mg/kg). Therefore a permit was obtained 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.

At the creek bank near water sampling site W-007, following approval by the Department of Fish and Wildlife, bioremediation additives were applied in late September to enhance natural microbial breakdown of the remaining petroleum. The objective is to accelerate natural processes in order to maximize removal prior to a significant rain event, while minimizing disturbance of the creek bank and vegetation. Contractors will resample the site at the end of October and compare the results with samples collected just prior to the application.

Planning for Fall Rains

While the storm drain system and the outfall are believed to have been sufficiently remediated, the Unified Command, VA and third-party contractor met to develop a plan to minimize the release of any lingering contaminated material during the rains. The plan includes additional booms just downstream of the outfall and coordinated monitoring by VA staff and City staff.

On-going Creek Monitoring

Throughout the remediation, Matadero Creek has been monitored at 16 locations for multiple chemicals related to diesel:

1. Total Petroleum Hydrocarbon as Diesel (TPH-Diesel) - a measurement of the suite of hydrocarbon compounds that typically make up diesel fuel.
2. Polyaromatic Hydrocarbons (PAHs) – individually measured compounds for which the Water Board has a specific water quality objective for each compound based on toxicity data.
3. Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) – four compounds found in gasoline and diesel for which the Water Board also has specific water quality objectives for each compound based on toxicity data.

Throughout the monitoring process, the primary constituent consistently detected has been TPH-diesel, rather than the individual PAH or BTEX species. Based on discussions with the Department of Fish and Wildlife, this is a positive outcome in that it is the individual PAH and BTEX compounds that would be expected to impact wildlife.

TPH-Diesel Results

Based on the most recent analytical data, it appears that the TPH-Diesel results at all water monitoring locations are below the Water Board goal of 640 ug/L.

PAH Results

To date, more than 14 PAH species have been analyzed on more than 220 water samples. As can be observed from the data tables, out of more than 2,900 combined analytical results for these PAH species, only 2 PAH species had a combined total of four values greater than the Water Board’s Habitat Goal, and no such value has been observed since mid-June.

BTEX Results

As can be observed from the data tables, while there have been more than 200 tests for BTEX, there was single finding of Xylene in early May at one location, and more recently one minor detection of toluene at another location; both were far below the Water Board’s Habitat Goal.

Creek Data and Map Update

All data are available by downloading the latest data table.

Download: Creek Water Sampling Table 1 and 2 With Map as of October 21, 2021(PDF, 1MB)

Summary

The Palo Alto Fire Department continues to consider the incident at Matadero Creek to be stable. Soil remediation continues on the VA property, while regular monitoring of the creek at 16 locations indicates that Matadero Creek is largely remediated, with no observed impacts to fish or wildlife. The sampling data continue to show that the boom system is still keeping the residual contained. All work is being conducted to ensure that wildlife remain protected throughout the remediation.

The 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 and review all aspects of the incident, including cause of the release, continued containment of the diesel and remediation of the soil and water. Action plans continue to evolve based on monitoring results and expert recommendations.

The storm drain system and drainage outfall to the creek were cleansed by the contractor team. Samples from the cleaned drainage network were collected and analyzed to identify locations that required additional cleaning, which was subsequently completed. The next remediation step is removing a limited amount of soil at the outfall, as well as applying bioremediation additives to enhance natural microbial breakdown of the petroleum remaining in the soil along the creek. Contractor work and neighboring wildlife activity continue to be closely monitored by representatives of the Unified Command.

Several Booms Removed to Encourage Natural Creek Flow

Several of the petroleum containment booms have been removed at the outer edges of the contaminated area, following approval from Fish and Wildlife. This will reduce the collection of aquatic plants on the boom network and encourage natural creek flow.

Soil Sampling Results and Remediation Steps

In August, soil samples were collected at the outfall in tandem with the storm drain sampling. A total of 12 soil samples were collected at different locations and depths between the outfall and the soil/water interface of the creek, to help locate possible residual diesel at the outfall site. Of the 12 samples, TPH-Diesel was detected in 10 of the samples, four of which were above the Water Board goal of 260 mg/kg (ranging from 290 to 3,300, with an average of 1,235 mg/kg). Therefore a permit is being obtained from Fish and Wildlife to remove a limited amount of soil at the outfall.

There remains diesel residue in soil sections along the creek bank near water sampling site W-007. In May, one soil sample at that site was found to contain 1,600 mg/kg, while all other locations along the boom network were well below the Water Board goal, with an average of 13 mg/kg and a maximum value of 83 mg/kg. Bioremediation additives will be applied to that section of the soil surface to enhance natural microbial breakdown of the remaining petroleum. Because the additives include very fine particles that are considered respiratory irritants, the contractors applying the material will wear personal protective equipment (PPE). Therefore, the public should not be alarmed if they notice workers equipped with PPE down in the creek bed.

The material being applied has been approved by the Department of Fish and Wildlife. Soil samples will be collected and analyzed before and after the application to monitor the biodegradation process. The project objective is to accelerate natural processes to maximize removal prior to a significant rain event, while minimizing disturbance of the creek bank and vegetation.

Public Asked Not to Disturb the Creek

The Department of Fish and Wildlife reminds the public to continue refraining from moving any material within the impacted section of the creek, as any adjustments could impact the rate and direction of water flow. This could inadvertently either cause the water to come into contact with contaminated soil or direct water flow around the boom network.

On-going Creek Monitoring

Throughout the remediation, Matadero Creek has been monitored at 16 locations for multiple chemicals related to diesel:

1. Total Petroleum Hydrocarbon as Diesel (TPH-Diesel) - a measurement of the suite of hydrocarbon compounds that typically make up diesel fuel.
2. Polyaromatic Hydrocarbons (PAHs) – individually measured compounds for which the Water Board has a specific water quality objective for each compound based on toxicity data.
3. Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) – four compounds found in gasoline and diesel for which the Water Board also has specific water quality objectives for each compound based on toxicity data.

Throughout the monitoring process, the primary constituent consistently detected has been TPH-diesel, rather than the individual PAH or BTEX species. Based on discussions with the Department of Fish and Wildlife, this is a positive outcome in that it is the individual PAH and BTEX compounds that would be expected to impact wildlife.

TPH-Diesel Results

The analysis continues to show periodic TPH-Diesel sample results above Water Board goals at W-007 due to a combination of naturally existing conditions that appear to have trapped small portions of the initial spill. Therefore limited treatment continues at this location. Meanwhile, according to Fish and Wildlife staff, these TPH-diesel values, while higher than the Water Board goal of 640 ug/L, are not the typical indicator of possible impact to wildlife. Rather, it is the more specific compounds within diesel, that of PAH and BTEX, that are of greater concern from a habitat perspective.

PAH Results

To date, more than 14 PAH species have been analyzed on more than 220 water samples. As can be observed from the data tables, out of more than 2,900 combined analytical results for these PAH species, only two PAH species had a combined total of four values greater than the Water Board’s Habitat Goal, and no such value has been observed since mid-June.

BTEX Results

As can be observed from the data tables, while there have been more than 200 tests for BTEX, there was single finding of Xylene in early May at one location, and more recently one minor detection of toluene at another location; both were far below the Water Board’s Habitat Goal.

Creek Data and Map Update

As noted above, the boom areas that the team is closely monitoring are between W-006 and W-008 on the map, due to the TPH-Diesel values. All data are available by downloading the latest data table below.

Download: Creek Water Sampling Table 1 and 2 With Map as of September 21, 2021(PDF, 1MB)

Summary

The Fire Department continues to consider the incident at Matadero Creek to be stable. Soil remediation continues on the VA property while regular monitoring of the creek at 16 locations indicates that Matadero Creek is largely remediated with no observed impacts to fish or wildlife. The sampling data continue to show that the boom system is still keeping the residual contained. All work is being conducted to ensure that wildlife remain protected throughout the 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, including cause of the release, continued containment of the diesel and remediation of the soil and water. Action plans continue to evolve based on monitoring results and expert recommendations.

The storm drain system and drainage outfall to the creek have been cleansed by the contractor team; samples from the cleaned drainage network have been collected and will be analyzed to ensure the completeness of that work. The next remediation step is the application of bioremediation additives to enhance natural microbial breakdown of the petroleum remaining in the soil along the creek. Contractor work and neighboring wildlife activity continue to be closely monitored by representatives of the Unified Command.

Suspected Algal Buildup Was Free-Floating Aquatic Plant Matter

Per the last public update, concerned members of the public had previously reported observing algal buildup along the boom network. Because algal growth and subsequent decay can reduce the oxygen concentration in water, the remediation contractor obtained approval from Fish and Wildlife to reduce the algal growth in the areas where buildup was next to the booms. Upon closer evaluation of the collected material, it was discovered to be free-floating aquatic plants. While that eliminates any concern about reduced oxygen in the water, if more organic material is observed to be restricting flow through the boom network, the contractor may remove it using the method previously approved by Fish and Wildlife.

Enhanced Soil Treatment Anticipated to Begin in Early September

Diesel residue remains in discrete soil sections along the creek bank. Beginning in early September, bioremediation additives are expected to be applied to the soil surface to enhance natural microbial breakdown of the remaining petroleum. Because the additives include very fine particles that are considered respiratory irritants, the contractors applying the material will be wearing personal protective equipment (PPE). Therefore, the public should not be alarmed if they notice workers equipped with PPE down in the creek bed.

The material being applied has been approved by the Department of Fish and Wildlife. Soil samples will be collected and analyzed before and after the application to monitor the biodegradation process. The project objective is to accelerate natural processes to maximize removal prior to a significant rain event, while minimizing disturbance of the creek bank and vegetation.

Public Asked Not to Disturb the Creek

The Department of Fish and Wildlife reminds the public to continue to refrain from moving any material within the impacted section of the creek, as any adjustments could impact the rate and direction of water flow. This could inadvertently either cause the water to come into contact with contaminated soil or direct water flow around the boom network.

On-going Creek Monitoring

Throughout the remediation, Matadero Creek has been monitored at 16 locations for multiple chemicals related to diesel:

1. Total Petroleum Hydrocarbon as Diesel (TPH-Diesel) - a measurement of the suite of hydrocarbon compounds that typically make up diesel fuel.
2. Polyaromatic Hydrocarbons (PAHs) – individually measured compounds for which the Water Board has a specific water quality objective for each compound based on toxicity data.
3. Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) – four compounds found in gasoline and diesel for which the Water Board also has specific water quality objectives for each compound based on toxicity data.

Throughout the monitoring, the primary constituent consistently detected has been that of the overall measurement of TPH-diesel, rather than the individual PAH or BTEX species. Based on discussions with the Department of Fish and Wildlife, this is a positive outcome in that it is the individual PAH and BTEX compounds that would be expected to impact wildlife.

TPH-Diesel Results

The analysis continues to show periodic TPH-Diesel sample results above Water Board goals at W-007, due to a combination of naturally existing conditions that appear to have trapped small portions of the initial spill; therefore limited treatment continues at this location. Meanwhile, according to Fish and Wildlife staff, these TPH-diesel values, while higher than the Water Board goal of 640 ug/L, are not the typical indicator of possible impact to wildlife. Rather, it is the more specific compounds within diesel, that of PAH and BTEX, that are of greater concern from a habitat perspective. 

In mid-July, sites W-012 and W-013 showed an uptick in TPH, with analytical values greater than had been seen at either site since May 11. Because this particular lab analysis can pick up organic material other than TPH, including natural organics (e.g., humus) and petroleum decomposition products, the analysis of both samples was repeated using a process that first removes non-TPH hydrocarbons. The lab results have since indicated “diesel range compounds detected, no recognizable pattern” suggesting that these samples did contain diesel residual. Meanwhile, these sites have continued to be monitored and the values are once again below the Water Board goal.

PAH Results

To date, more than 14 PAH species have been analyzed on more than 220 water samples. As can be observed from the data tables, out of more than 2,900 combined analytical results for these PAH species, only two PAH species had a combined total of four values greater than the Water Board’s Habitat Goal, and no such value has been observed since mid-June.

BTEX Results

As can be observed from the data tables, while there have been more than 200 tests for BTEX, there was single finding of Xylene in early May at one location, and more recently one minor detection of toluene at another location; both were far below the Water Board’s Habitat Goal.

Creek Data and Map Update

As noted above, the boom areas that the team is closely monitoring are between W-006 and W-008 on the map, and only due to the TPH-Diesel values. All data are available by downloading the latest data table below.

Download: Creek Water Sampling Table 1 and 2 With Map as of August 27, 2021(PDF, 962KB)

The Fire Department continues to consider the incident at Matadero Creek to be stable. Soil remediation continues on the VA property, while regular monitoring of the creek at 16 locations indicates that Matadero Creek is largely remediated with no observed impacts to fish or wildlife. The sampling data continue to show that the boom system is still keeping the residual contained.  All work is being conducted to ensure that wildlife remain protected throughout the 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 3rd party remediation and environmental scientist experts.

Representatives from regulatory agencies continue to meet to review all aspects of the incident, including cause of the release, continued containment of the diesel and remediation of the soil and water. Action plans continue to evolve based on monitoring results and expert recommendations.

 Anticipated next steps include application of bioremediation additives to enhance natural microbial breakdown of the petroleum remaining in the soil along the creek. Soil samples will be collected before and after the application to monitor the degradation. In addition, areas with algal build-up are being attended via methods approved by the Fish and Wildlife Service.

 At the VA hospital, remediation work is ongoing and will soon include a cleansing of the impacted storm drain, including the drainage outfall to the creek. This work will be closely monitored by representatives of the Unified Command.

Identified Algal Buildup Being Addressed

It has been observed that naturally occurring algae appears to be restricted from flowing downstream, and is building up at a few locations along the boom network. Algal buildup is naturally occurring in other areas of the creek where water pools up and stagnates. Because algal growth and subsequent decay can reduce the oxygen concentration in water, the remediation contractor has obtained approval from Fish and Wildlife to use pool skimming equipment to reduce the algal growth only in the areas where buildup is next to the booms.

Public Asked Not to Disturb the Creek

The Department of Fish and Wildlife asks that the public refrain from moving any material within the impacted section of the creek, as any adjustments could impact the rate and direction of water flow, which could inadvertently cause the water to come into contact with contaminated soil or direct water flow around the boom network. Furthermore, from a public health standpoint, in principle any material from the impacted portion of the creek is considered hazardous unless established to be nonhazardous by lab analysis.

Wildlife

There continues to be visible muskrat activity along the creek, demonstrating that the remediation efforts appear not to be interfering with wildlife. Representatives of Fish and Wildlife want to assure the public that while the algal buildup is being reduced to prevent oxygen depletion within the water, the muskrats (and other mammals) have not been impacted by the algae presence since their oxygen source is from the air above the water surface.

Ongoing Creek Monitoring

Throughout the remediation, Matadero Creek has been monitored at 16 locations for multiple chemicals related to diesel:

1. Total Petroleum Hydrocarbon as Diesel (TPH-Diesel) - a measurement of the suite of hydrocarbon compounds that typically make up diesel fuel.
2. Polyaromatic Hydrocarbons (PAHs) – individually measured compounds for which the Water Board has a specific water quality objective for each compound based on toxicity data.
3. Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) – four compounds found in gasoline and diesel for which the Water Board also has specific water quality objectives for each compound based on toxicity data.

Throughout the monitoring, the primary constituent consistently detected has been that of the overall measurement of TPH-diesel, rather than the individual PAH or BTEX species. Based on discussions with the Department of Fish and Wildlife, this is a positive outcome in that it is the individual PAH and BTEX compounds that would be expected to impact wildlife.

TPH-Diesel Results

The analysis continues to show periodic TPH-Diesel sample results outside of normal limits between W-008 and W-006, as well as occasionally just downstream at W-005. Third party experts suggest this may be due to limited sunlight exposure, a higher density of plants, and a natural in-creek obstruction to water flow. This combination of conditions may have trapped small portions of the initial spill;therefore limited treatment was initiated at this single location. Meanwhile, according to Fish and Wildlife staff, these TPH-diesel values, while higher than the Water Board goal of 640 ug/L, are not the typical indicator of possible impact to wildlife. Rather, it is the more specific compounds within diesel, that of PAH and BTEX, that are of greater concern from a habitat perspective.

In mid-July, sites W-012 and W-013 observed an uptick in TPH, with analytical values greater than had been seen at either site since May 11. Because this particular lab analysis can pick up organic material other than TPH, including natural organics (e.g., humus) and petroleum decomposition products, the analysis of both samples is being repeated using a process that first removes non-TPH hydrocarbons. The results (pending) will be compared with the original results. In addition, these sites will continue to be monitored to ensure that the values return to below the Water Board goal.

PAH Results

 To date, more than 14 PAH species have been analyzed on more than 220 water samples. As can be observed from the data tables, out of about 2,900 combined analytical results for these PAH species, only two PAH species had a combined total of four values greater than the Water Board’s Habitat Goal, and no such value has been observed since mid-June.

BTEX Results

 As can be observed from the data tables, while there have been more than 200 tests for BTEX, there was single finding of Xylene in early May at one location, and more recently one minor detection of toluene at another location; both were far below the Water Board’s Habitat Goal.

Soil Treatment

There remains diesel residue in soil along the creek bank near the outfall. The Department of Fish and Wildlife, VA staff, and consultants evaluated options to enhance bioremediation. Anticipated next steps include additional light soil tilling and the application of bioremediation additives to enhance natural microbial breakdown of the petroleum remaining in the soil along the creek. Soil samples will be collected and analyzed before and after the application to monitor the biodegradation process. The project objective is to accelerate natural processes in order to maximize removal prior to a significant rain event, while minimizing disturbance of the creek bank and vegetation.

Creek Data and Map Update

As noted above, the boom areas that the team are closely monitoring are between W-006 and W-008 on the map, and only due to the TPH-Diesel values. All data are available by downloading the latest data table below.

Download: Creek Water Sampling Table 1 and 2 With Map as of August 13, 2021(PDF, 471KB)

The Fire Department continues to consider the incident at Matadero Creek to be stable. Soil remediation continues on the VA property while regular monitoring of the creek at 16 locations indicates that Matadero Creek is largely remediated with no observed impacts to fish or wildlife. The sampling data continue to show that the boom system is continuing to keep the residual contained. All work is being conducted to ensure that wildlife remain protected throughout the 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 3rd party remediation and environmental scientist experts. Representatives from regulatory agencies continue to meet to review all aspects of the incident, including cause of the release, continued containment of the diesel and remediation of the soil and water. Action plans continue to evolve based on monitoring results and expert recommendations.

On-going Creek Monitoring

Throughout the remediation, Matadero Creek has been monitored at 16 locations for multiple chemicals related to diesel:

1. Total Petroleum Hydrocarbon as Diesel (TPH-Diesel) - a measurement of the suite of hydrocarbon compounds that typically make up diesel fuel.
2. Polyaromatic Hydrocarbons (PAHs) – individually measured compounds for which the Water Board has a specific water quality objective for each compound based on toxicity data.
3. Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) – four compounds found in gasoline and diesel for which the Water Board also has specific water quality objectives for each compound based on toxicity data.

Throughout the monitoring, the primary constituent consistently detected has been that of the overall measurement of TPH-diesel, rather than the individual PAH or BTEX species. Based on discussions with the Department of Fish and Wildlife, this is a positive outcome in that it is the individual PAH and BTEX compounds that would be expected to impact wildlife.

TPH-Diesel Results

The analysis continues to show periodic TPH-Diesel sample results outside of normal limits between W-008 and W-006 as well as occasionally just downstream at W-004. Third party experts suggest this may be due to limited sunlight exposure, a higher density of plants, and a natural in-creek obstruction to water flow. This combination of conditions may have trapped small portions of the initial spill. Therefore limited treatment was initiated at this single location. Meanwhile, according to Fish and Wildlife staff, these TPH-diesel values, while higher than the Water Board goal of 640 ug/L, are not the typical indicator of possible impact to wildlife. Rather, it is the more specific compounds within diesel, that of PAH and BTEX, that are of greater concern from a habitat perspective.

In mid-July, sites W-012 and W-013 observed an uptick in TPH, with analytical values greater than had been seen at either site since May 11. Because this particular lab analysis can pick up organic material other than TPH, including natural organics (e.g., humus) and petroleum decomposition products, the analysis of both samples is being repeated using a process that first removes non-TPH hydrocarbons. The results (pending) will be compared with the original results. In addition, these sites will continue to be monitored to ensure that the values return to below the Water Board goal.

PAH Results

To date, more than 14 PAH species have been analyzed on more than 200 water samples. As can be observed from the data tables, out of about 2,900 combined analytical results for these PAH species, only 2 PAH species had a combined total of 4 values greater than the Water Board’s Habitat Goal and no such value has been observed since mid-June.

BTEX Results

As can be observed from the data tables,  while there have been more than 200 tests for BTEX, only a single finding of Xylene in early May at one location has ever been detected at the site, and it was far below the Water Board’s Habitat Goal.

Wildlife

A concerned resident and animal advocacy group met with the Fire Department’s Hazmat staff and VA staff to point out the location of a possible muskrat den along the creek and discuss how to ensure that remediation efforts not disturb the den. The resident has since reported seeing continued muskrat activity, demonstrating that the remediation efforts appear not to be interfering with wildlife.

Water and Soil Treatment

Earlier in July there were efforts to mobilize diesel product remaining on the water surface and direct it to the downstream booms. The work to mobilize diesel product is no longer underway based on visual observations that the effort appeared to have had the desired effect.

There remains diesel residue in soil along the creek bank near the outfall. The Department of Fish and Wildlife, VA staff, and consultants are evaluating options to enhance bioremediation through additional hand tilling and/or biotreatment additives. The shared objective is to develop a strategy to accelerate natural processes in order to maximize removal prior to a significant rain event while minimizing disturbance of the creek bank and vegetation.

Creek Data and Map Update

The boom areas that the team is closely monitoring are between W-006 and W-008 on the map and only due to the TPH-Diesel values. All data are available by downloading the latest data table.

Download: Creek Water Sampling Table 1 and 2 With Map - August 3, 2021(PDF, 889KB)

Additional Sampling Data

• Water Quality Data Summary - As of June 15, 2021(PDF, 677KB)
• Water Quality Data Summary - As of May 28, 2021(PDF, 162KB)

The Fire Department continues to consider the incident at Matadero Creek to be stable. Soil remediation continues on the VA property while regular monitoring of the creek at 16 locations indicates that Matadero Creek is largely remediated with no observed impacts to fish or wildlife. The sampling data continue to show that the boom system has performed optimally. On a recent creek visit, all booms were blue in color (booms turn pink as they absorb petroleum) and there was no diesel odor anywhere along the creek (see fig. 1).

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 3rd party remediation and environmental scientist experts. Representatives from regulatory agencies continue to meet to review all aspects of the incident, including cause of the release, continued containment of the diesel and remediation of the soil and water. Action plans continue to evolve based on monitoring results and expert recommendations.

On-going Creek Monitoring

Throughout the remediation, Matadero Creek has been monitored at 16 locations for multiple chemicals related to diesel:

1. Total Petroleum Hydrocarbon as Diesel (TPH-Diesel) - a measurement of the suite of hydrocarbon compounds that typically make up diesel fuel.
2. Polyaromatic Hydrocarbons (PAHs) – individually measured compounds for which the Water Board has a specific water quality objective for each compound based on toxicity data.
3. Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) – four compounds found in gasoline and diesel for which the Water Board also has specific water quality objectives for each compound based on toxicity data.

Throughout the monitoring, the primary constituent consistently detected has been that of the overall measurement of TPH-diesel, rather than the individual PAH or BTEX species. Based on discussions with the Department of Fish and Wildlife, this is a positive outcome in that it is the individual PAH and BTEX compounds that would be expected to impact wildlife.

TPH-Diesel Results

The analysis continues to show periodic TPH-Diesel sample results outside of normal limits between W-008 and W-006 as well as occasionally just downstream at W-004. Third party experts suggest this may be due to limited sunlight exposure, a higher density of plants, and a natural in-creek obstruction to water flow (see fig. 2). This combination of conditions may have trapped small portions of the initial spill. Therefore limited treatment was initiated at this single location. Meanwhile, according to Fish and Wildlife staff, these TPH-diesel values, while higher than the Water Board goal of 640 ug/L, are not the typical indicator of possible impact to wildlife. Rather, it is the more specific compounds within diesel, that of PAH and BTEX, that are of greater concern from a habitat perspective.

PAH Results

To date, more than 14 PAH species have been analyzed on more than 190 water samples. As can be observed from the data tables, out of about 2,900 combined analytical results for these PAH species, only 2 PAH species had a combined total of 4 values greater than the Water Board’s Habitat Goal and no such value has been observed since mid-June.

BTEX Results

As can be observed from the data tables, of the 190 tests for BTEX, only a single finding of Xylene at one location has ever been detected at the site, and it was far below the Water Board’s Habitat Goal.

Water and Soil Treatment

Due to the lingering TPH-Diesel between W-006 and W-008, the Department of Fish and Wildlife met with third-party industry experts to generate a plan to mobilize the remaining diesel product on the water surface and in the soil adjacent to the water’s edge just upstream of the in-creek obstruction. The work, which was completed July 13th, involved 3 components:

• Vegetation Removal: Using hand tools, vegetation above the water line and along the shore near site W-007 was trimmed (leaving the roots) to mobilize and/or expose any remaining material trapped in the vegetation to aid in natural attenuation.
• Flushing: To encourage water movement in that area, low pressure ambient water was used to mobilize any diesel product remaining on the surface trapped by vegetation or other obstructions. Any observable diesel product was directed toward the boom immediately downstream for collection by the sorbent.
• Light tilling: The top 1-2 inches of soil around site W-007 was lightly scrapped in order to expose the area to sunlight. The work was minimal in scope in order to expose remaining pollutants while preserving the ecosystem and creek banks.

Creek Data and Map Update

As noted above, the boom areas that the team is closely monitoring are between W-006 and W-008 on the map, and only due to the TPH-Diesel values. All data are available by downloading the latest data table below.

Download: Creek Water Sampling Table 1 and 2 With Map - July 15, 2021(PDF, 796KB)

The Palo Alto Fire Department remains in Unified Command, which means the fire department is working as a cohesive unit through all phases of this incident with, California Department of Fish and Wildlife, and other regional regulators, and in partnership with the VA Palo Alto Health Care System. The Palo Alto Fire Department continues to consider the incident as stable at this time.

Representatives from regulatory agencies continue to meet to review all aspects of the incident, including cause of the release, continued containment of the diesel and remediation of the soil and water. Action plans continue to evolve based on daily testing, other analysis completed and expert recommendations. VA Palo Alto representatives, 3rd party remediation scientist/water sample experts, Palo Alto Fire Department Hazmat Bureau, California Department of Fish and Wildlife, City of Palo Alto Stormwater staff, and Santa Clara Valley Water Board are all working collaboratively.

Creek Water Sampling/Testing Continues

Ongoing creek analysis has shown two sample results outside of normal limits between W-008 and W-006.  Third party experts suggest this may be due to limited sunlight exposure and a higher density of plants and foliage, creating an area that may have trapped the initial spill and causing the elevated levels.  The sampling data further shows that the boom system is performing optimally as this section is the only area out of normal limits.

Creek Data and Map Update

As noted above, the boom areas that we are closely watching are between W-006 to W-008 (demarcated by red arrows below).  All other areas are now within normal limits per water quality standards.

Download: Creek Water Sampling Table 1 and 2 With Map - June 23, 2021(PDF, 677KB)

Soil Mitigation & Other Completed/Ongoing Work

The Department of Fish and Wildlife will be meeting with the third-party industry experts next week to determine a plan to appropriately till the soil adjacent to the creek bed, to maximize extraction of any remaining pollutants while focusing on preserving the ecosystem to further reduce all affected areas.  

Representatives from regulatory agencies, Palo Alto Fire Department (PAFD) and third-party consultants met on-site this week to determine soil sampling locations and to make appropriate decisions on mitigation techniques at the initial point of the spill outside of the generator room. Sampling was done on Thursday, June 17, 2021.  As of this update, results are pending.

The Palo Alto Fire Department remains in Unified Command, which means the fire department is working as a cohesive unit through all phases of this incident with, California Department of Fish and Wildlife, and other regional regulators, and in partnership with the VA Palo Alto Health Care System. The Palo Alto Fire Department continues to consider the incident as stable at this time.

Representatives from regulatory agencies continue to meet to review all aspects of the incident, including cause of the release, continued containment of the diesel and remediation of the soil and water. Action plans continue to evolve based on daily testing, other analysis completed and expert recommendations. VA Palo Alto representatives, 3rd party remediation scientist/water sample experts, Palo Alto Fire Department Hazmat Bureau, California Department of Fish and Wildlife, City of Palo Alto Stormwater staff, and Santa Clara Valley Water Board are all working collaboratively.

Creek Water Sampling/Testing Continues & Interpretation of Data Underway

Regulatory agencies continue to monitor the diesel values in the creek. The data demonstrates that a spill occurred. Additional testing and different type of testing is underway, to better understand the specific contaminates in the water, specific diesel spill levels and to rule out amounts of chemicals within the sampling site not related to the incident. It is not uncommon for these types of water ways to have contaminants from street runoff or other sites. Creek water testing continues regularly.

Creek analysis and data showed three past results that were outside of normal limits downstream from the last containment boom; however, VA third party experts suggests the most recent results from the same location show levels within normal limits. The early results could be indicative of several potential contributing factors such as organic sediment naturally occurring in the creek affecting the sample, contaminated soil disruption around the creek bank or movement/replacement of containment booms. Other causes will be ruled out with more data collection.

Preliminary Creek Data and Map Released

Water quality samples have been regularly collected within the boom containment area since the diesel spill occurred. The tables(PDF, 417KB) present data collected at two locations (see Map for reference point locations). Data was collected immediately after the spill upstream as a control (point of reference) location (W-016) and downstream of the boom containment area (W-003). Since the release of the data, two more booms were installed upstream of W-003 and upstream of W-002, since it appears that some of the contaminants may be making their way through the containment zone, as indicated in the W-003. In addition, samples were collected within the boom containment area and as anticipated with a diesel spill, the values of Total Petroleum Hydrocarbons-Diesel remain above the water quality habitat goals of 640 micrograms per liter, in four locations. California Department of Fish and Wildlife anticipates that the diesel will naturally attenuate over a timeframe of months; therefore, other clean up alternatives are currently being explored. With the movement of the creek, the booms in place to absorb any remaining fuel products, and the natural degradation of fuel, VA third party experts expect the values to continue on a downward trend. Sampling results have been provided to the City as the VA receives them and results will be released publicly online as they become available.

Extension of Containment Booms Downstream

Containment booms have been inspected regularly, and verified by California Department of Fish and Wildlife, and Palo Alto Fire Hazmat Inspectors. In an abundance of caution, Palo Alto Fire Department has directed the extension of the containment boom network by adding two additional boom systems downstream, as noted above. 

Public Assistance Requested & New Signage

California Department of Fish and Wildlife has reiterated that the creek is not classified as a recreational waterway. There have not been any reports of dead or injured wildlife related to this incident. 

As the investigation continues, the Palo Alto Fire Department is asking the public’s help to ensure the creek and surrounding habitat are avoided so that regulatory agencies can continue to monitor the creek water and related areas. As a result, signage will be posted to remind the public of this active investigation and to avoid the creek until the investigation is concluded, which could continue for several weeks.

Soil Mitigation & Other Completed/Ongoing Work

• Regulatory agencies involved will continue to adjust action plans as data is analyzed and reviewed with experts.
• Initial soil mitigation has been completed around the VA generator building. Vacuum trucks have removed contaminated soil and remaining soil has been tested.
• The initial deep cleaning of the generator and room has been completed.
• The storm drain in the area remains covered and the outflow pipe is plugged to ensure containment of any diesel. A plan is being developed to clean the entire system, collect any runoff, and provide laboratory sampling to ensure no contaminants remain in the system.

The Palo Alto Fire Department Prevention Bureau accepted submittals for all four focus areas of the incident from the contracted 3^rd party mitigation company on behalf of the VA Palo Alto Health Care System.  These four focus areas include: soil remediation, water in the creek, storm drainage system, and the building.  Each division will have associated Hazmat Closure Permits, and follow closure protocols for Palo Alto Fire Prevention, and the City of Palo Alto. Soil remediation has been approved to start final remediation work beginning on Monday, May 24, 2021. This will include contaminated soil removal on the ground around the generator building witnessed by Hazmat Inspectors from the Palo Alto Fire Department, and soil sampling and reviewing results will occur prior to completion of this work.

Creek inspections and water samples have continued throughout the week with contracted 3^rd party remediation service, California Department of Fish and Wildlife, and Palo Alto Fire Department. Containment and absorbent booms (pads floating on the water to absorb any diesel) remain in place as recommended by experts and California Department of Fish and Wildlife. There are no signs of saturation of diesel reported in the booms and they will continue to be inspected daily. Water samples have continued both in and out of the containment area of the creek and are expected to show trends towards normal limits.

California Department of Fish and Wildlife noted that no animals have been reported injured or harmed as a result of the release into the creek. One deceased rat was collected, but it is not suspected to be related to the incident. California Department of Fish and Wildlife has expressed their content with containment and mitigation efforts for the creek and will continue to support the process.

On May 21, a meeting was held with the VA contracted site sampling expert with all involved agencies. Water sampling will continue on a regular basis in areas identified by the hired industry expert and approved by California Department of Fish and Wildlife staff Biologist and the Palo Alto Fire Hazmat Plan Examiner. Preliminary results have been reviewed and discussed by the contracted expert in the May 21, 2021 briefing, including:

• The majority of the samples have come back within normal limits.
• There are a couple of areas within the containment booms, the mitigation zone, that samples showed values outside of normal limits.
• Lab values downstream, outside of the containment zone, show to be within normal limits with new sample results pending to confirm the situation remains stable.
• Samples have been processed from the same area this week and are expected to trend downwards towards acceptable limits, results pending.

An all agency meeting is being formed with regulators and experts next week to analyze data, review submitted creek plan, and provide feedback. California Department of Fish and Wildlife will remain as lead on the Matadero Creek remediation with Palo Alto Fire Department and regulatory authorities.

All agencies are working well together and are committed to applying scientific methodology as all continue to work toward the goal of incident closure.

VA Palo Alto Health Care System (VAPAHCS) will continue testing of the Matadero Creek as directed by the Palo Alto Fire Department. While absorbents are not showing any additional diesel in the creek and the Palo Alto Fire Department has noted the incident as stable, official testing results are currently being reviewed by a VAPAHCS third party vendor. Once the lab results are analyzed and interpreted, an incident closure plan will be developed in collaboration with all agencies involved, including VAPAHCS, the Palo Alto Fire Department, Palo Alto Public Works Department and the State Fish and Wildlife Department. Review of lab results is expected to conclude this week.