Kristin Robrock
Kristin R. Robrock, Ph.D., P.E.
Managing Engineer
Environmental & Earth Sciences
Oakland

Dr. Robrock is an environmental engineer and microbiologist with 10 years of experience who specializes in biodegradation and the fate and transport of chemicals in the environment. Her expertise is on flame retardants, including polybrominated diphenyl ethers (PBDEs), chlorinated solvents, specifically PCE and TCE, perchlorate, metals, PCBs, and petroleum hydrocarbons in soil and groundwater. Dr. Robrock specializes in environmental forensics, reconstructing environmental releases to determine the timing, sources, and mechanisms of contaminant releases and identifying other potential sources of contamination. Dr. Robrock has also conducted numerous CERCLA cost allocation analyses.

Dr. Robrock is a California licensed civil engineer and provides technical consulting on the appropriateness of remediation activities and costs, as well as compliance with the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). She has also evaluated standards of the practice for historical environmental assessments and testified as an expert witness.

CREDENTIALS & PROFESSIONAL HONORS

  • Ph.D., Environmental Engineering, University of California, Berkeley, 2008
  • M.S., Environmental Engineering, University of California, Berkeley, 2003
  • B.S., Earth and Environmental Engineering, Columbia University, 2001
  • Tien Scholar for Environmental Science and Biodiversity, 2007–2008

    University of California Toxic Substances Research and Teaching Program Fellowship, 2003–2005

    Civil and Environmental Engineering Graduate Student Fellowship, 2002–2003

    Tau Beta Pi Honor Society, 2000

LICENSES & CERTIFICATIONS

Licensed Professional Engineer, California, #77047

LANGUAGES

  • Italian
  • French

Publications

Shields WJ, Ahn S, Pietari J, Robrock K, Royer L. Atmospheric fate and behavior of POPs. Gwen O’Sullivan and Court Sandau, editors, Environmental Forensics for Persistent Organic Pollutants. Chennai: Elsevier, 2014, pp. 199–290.

Robrock KR, Mohn WW, Eltis LD, Alvarez-Cohen L. Biphenyl and ethylbenzene dioxygenases of Rhodococcus jostii RHA1 transform PBDEs. Biotechnol Bioeng 2011; 108(2):313–321.

Robrock KR, Coelhan M, Sedlak DL, Alvarez-Cohen L. Biodegradation of polybrominated diphenyl ethers by aerobic bacteria. Environ Sci Technol 2009; 43(15):5705–5711.

Zeng X, Robrock KR, Simonich SL, Alvarez-Cohen L, Korytár P, Barofsky DF. Application of a congener specific degradation model to study photodegradation, anaerobic biodegradation, and Fe0 reduction of polybrominated diphenyl ethers. Environ Toxicol Chem 2009; 29(40):770–778.

Zeng X, Simonich SL, Robrock KR, Korytár P, Alvarez-Cohen L, Barofsky DF. Development and validation of a congener specific photodegradation model for PBDEs. Environ Toxicol Chem 2008; 27(12):2427–2435.

Robrock KR, Korytar P, Alvarez-Cohen L. Pathways for the anaerobic microbial debromination of polybrominated diphenyl ethers. Environ Sci Technol 2007; 42(8):2845–2852.

He J, Robrock KR, Alvarez-Cohen L. Microbial reductive debromination of polybrominated diphenyl ethers (PBDEs). Environ Sci Technol 2006; 40(14):4429–4434.

Robrock KR, He J, Alvarez-Cohen L. Degradation of Polybrominated Diphenyl Ethers by Anaerobic Dehalogenating Cultures. Organohalogen Compounds 2005; 67:594–597.

Presentations

Robrock KR. Flame Retardants: An Overview of Environmental Regulations. AATCC Flammability Symposium, Cary, NC, September 2016.

Mesard PM and Robrock KR. Forensic Evaluation and Allocation of Heavy Metals in Surface Water Runoff from Multiple Sources to an Urban Lake. Battelle Sediment Conference, New Orleans, LA, January 2015.

Robrock KR. Is human activity a good predictor for polybrominated diphenyl ether (PBDE) concentrations in the Pacific Northwest? Groundwater Resources Association of California, Emerging Contaminants Conference, Concord, CA, February 2014.

Robrock KR, Cushing C, Kierski M. Polybrominated diphenyl ether concentrations in Columbia River sediment and fish compared to other areas in North America. Poster presentation. SETAC, Long Beach, CA, November 2012.

Robrock KR. Biotransformation of polybrominated diphenyl ethers by aerobic bacteria. IWA/GRA Micropol & Ecohazard, San Francisco, CA, June 2009.

Robrock KR. Aerobic biodegradation of polybrominated diphenyl ethers (PBDEs) by PCB-degrading bacteria. Norcal SETAC Conference, Berkeley, CA, May 2008.

Robrock K, Alvarez-Cohen L. Degradation of polybrominated diphenyl ethers by aerobic PCB-degrading organisms. Poster presentation, NIEHS Superfund Basic Research Program Meeting, Durham, NC, 2007.

Robrock KR. Biodegradation of polybrominated diphenyl ethers. California Water Environment Association Student Night, Oakland, CA, March 2007.

Robrock KR, Korytar P, Alvarez-Cohen L. Anaerobic microbial degradation pathways for seven environmentally relevant PBDE congeners. Poster presentation, 107th General Meeting for the American Society for Microbiology, Toronto, Canada, 2007.

Robrock KR, He J, Korytar P, de Boer J, Alvarez-Cohen L. Degradation of polybrominated diphenyl ethers (PBDEs) by Dehalococcoides species. Poster presentation, Groundwater Resources Association Emerging Contaminants in Groundwater, Concord, CA, 2006.

Robrock KR. Anaerobic microbial debromination of polybrominated diphenyl ethers. Association for Environmental Health and Sciences West Coast Conference, San Diego, CA, March 2006.

Robrock KR, He J, Korytar P, de Boer J, Alvarez-Cohen L. Degradation of polybrominated diphenyl ethers by Dehalococcoides species. Poster presentation, 106th General Meeting of the American Society for Microbiology, Orlando, FL, 2006.

Robrock KR. Anaerobic microbial debromination of polybrominated diphenyl ethers. Dioxin 2005 Conference, Toronto, Canada, August 2005.

Robrock K, Alvarez-Cohen L. Effect of triclosan on denitrifying bacteria. Toxic Substances Research & Teaching Program Annual Conference, Sacramento, CA, 2005.

Robrock K, Alvarez-Cohen L. Triclosan: Should we worry? Effects of triclosan on environmental microbial communities. Toxic Substances Research & Teaching Program Annual Conference, San Diego, CA, 2004.

Project Experience

Chlorinated Solvents

Investigated sources of chlorinated solvents to a VOC plume in Orange County, California. Evaluated the impact of a former transducer manufacturer to the groundwater VOC plume from post-remedial residual PCE concentrations in soils compared to other industrial sites in the region. Calculated potential PCE mass contribution to the VOC plume.

Investigated potential sources contributing to a large commingled PCE and Stoddard solvent plume originating from three nearby dry cleaners in northern California. Developed chlorinated solvent fingerprints for each dry cleaner to determine an allocation between the three parties for remediation costs. Analyzed historical sanitary sewer plans and specifications to determine potential contributions to the PCE plume from releases from the sanitary sewer.

Reviewed remediation work conducted at a former dry cleaner in northern California to assess whether it was conducted according to the standards of the practice at the time. Reconstructed historical release information and evaluated quantities of PCE present in the subsurface to determine whether PCE vapors in indoor air at an adjacent facility originated from PCE left in the subsurface after remediation activities were completed.

Analyzed contamination scenarios for PCE in dry cleaning facilities, determining the quantities of PCE that could be released to sewers from various disposal methods. Quantified potential releases to the subsurface through leaking sewer pipes.

Conducted a cost estimate for remediation of a PCE plume at a dry cleaner facility in Oakland. Analyzed data to determine extent of contamination and possible remediation strategies.

Investigated the timing of release of PCE at a dry cleaner facility in northern California. Evaluated costs for on-going remediation activities.

Conducted an NCP compliance study for remediation activities and costs at a large former manufacturing site in New York impacted with chlorinated solvents in a CERCLA cost recovery litigation.

Conducted a source and timing investigation at a former dry cleaning operation in northern California destroyed by a fire. Evaluated potential release mechanisms of PCE due to the fire.

Evaluated whether a Phase I Environmental Site Assessment met the standards of the practice at the time in a case involving vapor intrusion from a PCE-plume into an adjacent residential apartment building.

Metals and Salts

Investigated the sources of heavy metals for an urban lake contaminated with lead and other metals. Quantified the amount of lead present in the lake and yearly depositional patterns. Calculated the lead contamination from direct urban runoff and aerial deposition from an adjacent roadway from historical and present automobile use. Investigated other potential sources of lead from nearby residential, military, and industrial uses, and determined the total lead input from all sources of runoff in the watershed.

Determined historical hexavalent chromium concentrations in groundwater for a drinking water dose reconstruction case in California.

Conducted an NCP compliance evaluation for remediation costs of a hexavalent chromium-impacted former metal plating facility in southern California. Determined that selected activities conducted by the State of California to remediate the facility were inconsistent with the NCP and therefore the incurred costs were not recoverable.

Investigated sources of heavy metals, particularly copper, nickel and zinc, at a shipbuilding facility to assist with NPDES compliance for water discharged to the San Diego Bay from the graving dock. Determined quantities of heavy metals in the storm water drainage system at the site draining to the graving dock. Conducted water sampling to determine rates of heavy metal leaching from ship hulls and other surfaces in the graving dock. Assisted with creation of a water quality model to compare predicted copper loadings into the graving dock with actual measured quantities. Based on modeling results, determined the most important sources of copper to the graving dock. Determined several readily implementable recommendations for the shipbuilder to reduce copper loadings to achieve compliance with NPDES permit requirements.

Determined the mass allocation to the groundwater contamination from evaporation ponds at a coal-burning power plant in Nevada. Modeled seepage of salts and metals into the underlying groundwater for each evaporation pond. Calculated environmental cleanup costs owed by the two co-owners of the power plant.

Evaluated investigation and remediation activities for a perchlorate groundwater plume for a CERCLA cost recovery litigation. Evaluated investigations, remedial activities, and removal actions conducted at the site for NCP compliance. Determined costs associated with past environmental investigation and remedial activities and evaluated and critiqued proposed costs for future remediation activities. Investigated other potential sources of perchlorate in the area that could be impacting groundwater. Evaluated groundwater data and regional hydrogeology to assess the extent of the groundwater perchlorate plume and potential migratory pathways within the regional aquifer system. Assisted with groundwater modeling to determine future migration pathways and to reconstruct historical migration pathways for the groundwater plume.

Assessed ammonia in the Sacramento-San Joaquin Delta in California as part of a dispute regarding ammonia releases from a wastewater treatment plant. Analyzed and mapped ammonia concentrations throughout the Delta over time and calculated ammonia biodegradation rates. Identified and quantified potential ammonia sources to the Delta, including agricultural and urban runoff. Determined that ammonia EPA water quality criteria are attained throughout the Delta and that existing areas with elevated ammonia in parts of the Delta are unassociated with the wastewater treatment plant.

Assessed potential impacts from “soda blasting,” in which baking soda was used to remove paint from a residential property. Evaluated the mass of baking soda used and the fate baking soda after blasting. Conducted soil sampling to determine any changes to soil pH and sodium concentrations. Evaluated potential impacts to the asphalt roof from the baking soda by conducting Fourier transform infrared spectroscopy (FTIR) on a roof sample. Estimated costs to remediate a small area of the yard that was potentially impacted by baking soda.

Petroleum Hydrocarbons

Conducted a mass balance on a crude oil release along the coast in southern California to determine the amount of oil that reached the ocean for a Clean Water Act (CWA) fine. Calculated the approximate flow velocity of the oil. Determined rates of evaporation and biodegradation of the oil to account for losses before the oil reached the ocean and for losses from the oil recovered on land. Conducted a mass balance of the crude oil once it reached the ocean. Calculated oil volumes lost to evaporation and biodegradation, as well as the volumes of oil recovered from the ocean surface and beaches.

Reconstructed the volumes and timing of crude oil and produced water released during four separate spills at an oil production facility in central California. Estimated release volumes based on available information, including oil field pumping records, produced water reinjection records, cleanup records, as well as dimensions of the oil and produced water storage tanks.

Conducted a mass balance calculation for a gasoline release from an underground pipeline into a fractured bedrock aquifer. Calculated biodegradation rates for BTEX compounds from field data and estimated the mass of gasoline that had biodegraded since the release. Using VENT2D modeling, estimated the mass of gasoline that had evaporated from the soil shortly after the release.

Devised a sampling plan and conducted sampling of a hydrocarbon sheen on an urban estuary using a sheen-specific Teflon® net sampling device. Oversaw chemical fingerprinting of the collected sheen for source identification.

Other Contaminants


Prepared a soil management plan for the demolition of a former coastal power plant in California. The plan was meant to assist with identifying, sampling, and disposing of soils contaminated with PCBs, heavy metals, TPH, and PAHs during removal of demolished structures at the site. Prepared sampling plans for PCB-impacted concrete following EPA TSCA guidance in 40 CFR 761 and coordinated with EPA to obtain approval for disposal of PCB-impacted concrete. Prepared a soil sampling plan for determining any residual contamination after completion of demolition activities. Prepared a completion plan summarizing remaining contamination at the site after demolition activities were completed that distinguished between contamination associated with historical activities carried out by the former operator and contamination associated with new activities carried out by the current operator. Conducted a forensic analysis on TPH contamination present in site soils to determine the sources and ages of the TPH releases.

Investigated a PCB release associated with a vandalism event at a building undergoing demolition in northern California. Using PCB fingerprints, determined the extent of PCB contamination associated with the vandalism event and previously existing PCB contamination. Reviewed the reasonableness of costs for remediation and disposal of PCB-containing concrete and soil waste at a TSCA-approved disposal facility.

Assessed PBDE concentrations in fish and sediments in the Columbia River near a consortium of industrial facilities in Trail, British Columbia, Canada. Calculated doubling times and compared concentrations to fish and sediments in other areas of the Pacific Northwest. Compared PBDE concentrations to human health effect and ecological screening levels to assess potential risks from local fish consumption and exposure to sediments for humans and animals. Evaluated potential sources contributing PBDEs to the region.

Modeled the fate and transport of pesticides and herbicides sprayed at a Christmas tree farm in Washington State that were claimed to have impacted an adjacent cattle ranch. Modeled both aerial transport and deposition of liquid droplets as well as transport to an adjacent stream via stormwater runoff. Using biodegradation half-lives, estimated residual pesticide concentrations in downgradient vegetation and surface water runoff six months after spraying.

Evaluated the mobility of dense non-aqueous phase liquids (DNAPLs) from a former manufactured gas plant (MGP) present in sediments in the Chicago River. Oversaw DNAPL lab testing of the sediment samples using a centrifuge method (modified ASTM D425 and API RP40 [Dean-Stark method]) and water-drive method (API RP40) to determine the DNAPL saturations. Calculated the potential mobility of DNAPL based on theoretical principles and compared it to the laboratory results to determine that the DNAPL present in river sediments is below residual saturation levels and would likely not be mobile.

Prepared a sampling plan and conducted sampling of soils and hydraulic fluids in 55-gallon drums for chromium, dioxins, and VOCs from a former metal-plating facility.

Environmental Engineering

Investigated causes of flooding at a residential development from a stormwater system consisting of an underground stormwater sewer and a natural drainage channel. Oversaw topographic surveying and sewer surveying. Developed hydraulic grade lines and calculated volume of sediment to be removed to restore conveyance of stormwater through the channel.

Reviewed historical waste regulations, including RCRA and CWA, to determine the standard of the practice for construction, closure, and groundwater monitoring of surface impoundments for red mud, or alumina processing residue, at a former alumina facility in the Caribbean. Researched available records for alumina facilities worldwide to establish the standards of the practice for siting and construction of surface impoundments in the 1960s through 1980s. Reviewed literature of the hydraulic conductivity of red mud when used as a liner for surface impoundments.

Reviewed historical California and federal asbestos waste handling regulations to determine whether a former asbestos pipe manufacturing facility met the applicable regulations at the time.

Reviewed design criteria and estimated construction costs for a wastewater treatment plant upgrade in Pennsylvania as part of dispute over the standards of the practice. Analyzed the projected flow rates and projected NPDES effluent limits used as the design basis for the upgrade. Determined that the projected flow rates and NPDES effluent limits were appropriately developed. Determined that the design firm had appropriately developed and notified the client of estimated construction costs.

Assessed whether a request for “No Further Action” from the Regional Water Quality Control Board (RWQCB) for a site in southern California met the standards of the practice. Evaluated the chemical data and other information available at the time upon which the request was based to determine whether the information and understanding of that information was sufficient. Reviewed other sites in California that obtained “No Further Action” letters from the RWQCB to determine the environmental conditions at those sites at the time of their “No Further Action” requests.

Conducted an analysis of groundwater flow between two adjacent basins as part of a dispute over water replenishment costs in southern California. Researched hydrogeological information to determine the extent of the groundwater divide separating the basins. Compiled groundwater pumping and flow records to determine the volumes of water entering and exiting the basins. Determined that natural flow between the basins was not being accounted for in the replenishment assessment calculations used to establish costs for water replenishment activities in the basins.

Conducted a Reasonable Potential Analysis (RPA) for stormwater runoff at a site in southern California as part of an NPDES permit renewal. The RPA included metals, chlorinated organics, and phthalates. Reviewed and identified problems with an RPA conducted by the local RWQCB.

Conducted an RPA for metal-containing effluent discharged during shipbuilding and ship launching activities at a facility in southern California as part of an NPDES permit renewal.

Compiled water quality data, specifically hardness and sodium levels, for drinking water in major metropolitan cities throughout the United States. The data were to be used by a consumer products manufacturing client to determine the appropriate water quality to use in product testing.

Investigated chemical compounds likely historically present in stormwater runoff from a variety of industries with stormwater outfalls that discharged into a canal. Determined the historical periods during which stormwater runoff could have discharged to the canal and the specific discharge locations for each industry. Developed an allocation method for contributions from stormwater runoff based on surface area for each property as a proxy for historical stormwater flow rates and an allocation matrix for remedial design costs.

Oversaw daily dredging activities of PCB-contaminated sediment in a ship-loading channel in New York harbor for a metal recycling facility. The sediment was chemically stabilized and used for an experimental project involving stabilization of mining-impacted hillsides in Pennsylvania. Oversaw construction of a golf course on a brownfield using the stabilized sediment. Handled an extension of the dredging permit and performed field sampling. Assisted with design of the dredged channel.

Microbiology

Compiled anaerobic biodegradation rates for a cap design of contaminated lake sediments and calculated the range of expected half-lives. The contaminants of interest included BTEX, PAHs, chlorinated benzenes, phenol, and PCBs.

Reviewed chemical and biological data at a TCE-contaminated site undergoing enhanced bioremediation. Based on 16S Dehalococcoides and dechlorinating enzyme gene counts, assessed the progress of the remediation and recommended additional substrate injection.

Conducted a literature review of bacteria associated with foot odors in healthy people for an FDA 510K submission for anti-embolism stockings treated with the antimicrobial triclosan. Devised a testing protocol for determining the antimicrobial effectiveness of the stockings against appropriate odor-causing foot bacteria. Oversaw antimicrobial testing of stockings and determined appropriate odorous chemicals to analyze during a sniff test.

Knowledge

News & Events

CREDENTIALS & PROFESSIONAL HONORS

  • Ph.D., Environmental Engineering, University of California, Berkeley, 2008
  • M.S., Environmental Engineering, University of California, Berkeley, 2003
  • B.S., Earth and Environmental Engineering, Columbia University, 2001
  • Tien Scholar for Environmental Science and Biodiversity, 2007–2008

    University of California Toxic Substances Research and Teaching Program Fellowship, 2003–2005

    Civil and Environmental Engineering Graduate Student Fellowship, 2002–2003

    Tau Beta Pi Honor Society, 2000

LICENSES & CERTIFICATIONS

Licensed Professional Engineer, California, #77047

LANGUAGES

  • Italian
  • French