Wasteminz Conference October 2010 Dr Jill Sherwood Nelson Marlborough DHB Public Health Service
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Transcript of Wasteminz Conference October 2010 Dr Jill Sherwood Nelson Marlborough DHB Public Health Service
Assessment of public health risk from the remediation of the former Fruitgrowers Chemical Company site, Mapua:challenges and lessons learned
Wasteminz Conference October 2010
Dr Jill SherwoodNelson Marlborough DHB Public Health Service1Outline of PresentationBackground and context of the investigationWhat we foundConclusions ChallengesLessons learned2My intention today is to give you a bit of history as to how a public health investigation into the Mapua Site remediation came about, our objectives and the approach we used; to outline what we found during our investigation and how this impacted on the completeness of the risk assessment we undertook. Although I will briefly present our findings and conclusions, my main purpose is to highlight challenges encountered and lessons learned that may be helpful in future projects of a similar nature.
BackgroundSite activitiesPesticides factory, mineral processing plant, private landfill1932 1988Site left orphanedHistoric contaminationEnvironmental and public health risk assessed in 1990sRemediation planned
Location of Mapua SiteMapua is a small coastal community located between Nelson and Motueka at the mouth of the Waimea Estuary. Originally a small holiday settlement t has become more urbanised over the years. As a result what I will refer to as the Mapua Site is now surrounded by a residential area, with some commercial outlets and restaurants in the old wharf area.The Mapua Site was home to a pesticides factory etc Range of chemicals were produced or stored on Site including organo mercury and arsenical compounds, organochlorine pesticides and organophosphate compounds.Site left orphaned: Resulting contamination of soil, marine sediments, groundwater recognisedSeveral reports in 1990s outlining environmental and public health risk
The main concern for human health risk if the site was left as is were the organochlorines mainly DDX (term for DDT and associated compounds) there was risk of exposure particularly from skin contact with or ingestion of contaminated soil, ingestion of contaminated groundwater, or ingestion of contaminated shellfish
This risk was considered unacceptable. Several options for remediation considered. Cap and Contain planned by Tasman District Council. Then decided to remediate it the purpose was to reduce the contaminant concentrations in soil and marine sediment to levels acceptable for future use of the Site and surrounding areas.
Several remediation options were considered before the decision was made to use the new technology of mechanochemical dehalogenation and to remediate the soil on the Site itself. Details of this may be found in PCE Report 2008.
3Protected disclosureMapua Site remediation commenced 2004Concerns raised about remediation process 2006Agencies involved in investigationParliamentary Commissioner for the Environment, Ministry of Health, Department of LabourPublic Health Service involvement Requested to undertake investigation for MoH
In 2006 concerns were raised with the PCE about the Mapua Site remediation and a preliminary investigation showed 3 main areas requiring investigation: Poor environmental management, potential public health impacts, and potential worker health issues.The relevant agency undertook further investigation with the MoH requesting the PHS to undertake the investigation into the potential public health issues.
4Public Health BriefInvestigate the possibility of risk to public healthRisk of exposure to any emissions and discharges Risk to health of the populationFrom the start of the remediation5The goal of the investigation was to investigate the possibility of risk to public health from the start of the remediation. And the main areas of interest were to assess the risk of exposure to any discharges or emissions from the site. And then assess whether there was risk to public health.
Information gatheringIdentify possible hazardsResource consent conditions for protection of public health and review of monitoring resultsCommunity concernsRisk assessment of hazards of concernChemicals included in the total hazard index other hazards if health impact appeared possible6Info gathering: Identify hazards, remediation process, review what had been put in place for protection of public health by: resource consent conditions ambient air and groundwater monitoring programmes, specific control and mitigation activities for identified hazards (eg dust)Risk assessment THI and lit review and expert opinion.
Seemed straight forward so we started with a site visit.
The teamGradually discovered that this was going to more complicated than we had thought.7
In the soil or groundwaterTesting prior to remediationBaseline sampling early in the remediationUnexpected finds during the remediationResulting from the remediation processBy-products formed in soil dryerBy-products formed in MCD reactorOtherDustNoise and/or vibrationOdour
8Site characterisation: Soil and groundwater testing prior to remediation mainly identified OCPs (DDX and dieldrin) and some heavy metals, Several other chemicals were noted to be elevated in some areas of the Site during the Baseline sampling or were uncovered during the excavations once the cleanup had started. The PC noted the range of testing prior to the remediation starting may have been inadequate to assess the risk from all hazards.
Other chemicals resulted from process show diagram and talk through briefly
9Just describe the process very briefly - Site Activities, Soil dryer, Air Emissions Control System, MCD reactor
Exposure indicate where emissions occurring
3 routes by which emissions/discharges might leave the Site. Stack emissions could be hazards know to be in the soil going through the dryer that went up the stack instead of on to the reactor (eg DDX) or a by-product formed in the dryer (eg benzene, dioxins) both situations were most likely to occur when dryer temperature was higher. However if the air emissions control system was functioning optimally these would largely have been removed by the system and not released from the stack frequent malfunctioning of AECS during the first year of operation of the remediation plant means this is the main period of concern for stack emissions having higher concentrations of some chemicals.Fugitive emissions could come from several sources:as dust from excavation work and the soil piles PM10, chemicals (significant component of the OCP emissions from the Site); from volatilisation of chemicals from the soil piles; back pressure in the dryer causing release of chemicals into store shed area or surrounding open air (thought to occur especially in the first year of operation by PCE eg OCPs, dioxins); from the reactor (mostly likely in area of pug mill) (eg benzene and ammonia into the air) Groundwater discharges from leaching of contaminants from the soil (eg OCPs)
Exposure PotentialSummary as how hazards might leave the SiteStack emissionsFugitive emissionsGroundwater discharges
Exposure show diagram and say: There are 3 routes by which emissions/discharges might leave the Site. Stack emissions could be hazards know to be in the soil going through the dryer that went up the stack instead of on to the reactor (eg DDX) or a by-product formed in the dryer (eg benzene, dioxins) both situations were most likely to occur when dryer temperature was higher. However if the air emissions control system was functioning optimally these would largely have been removed by the system and not released from the stack frequent malfunctioning of AECS during the first year of operation of the remediation plant means this is the main period of concern for stack emissions having higher concentrations of some chemicals.Fugitive emissions could come from several sources:as dust from excavation work and the soil piles PM10, chemicals (significant component of the OCP emissions from the Site); from volatilisation of chemicals from the soil piles; back pressure in the dryer causing release of chemicals into store shed area or surrounding open air (thought to occur especially in the first year of operation by PCE eg OCPs, dioxins); from the reactor (mostly likely in area of pug mill) (eg benzene and ammonia into the air) Groundwater discharges from leaching of contaminants from the soil (eg OCPs)
10Site activities during remediation (early 2007)
Issues re Exposure InformationMonitoringnot all contaminants of concern monitored PM10 not monitoredPUF filters not suitable to measure TSPTahi Street monitoring station locationNo background monitoring station
ModellingOCPs poor correlationDioxins uncertainty due to assumptions in model
13Exposure was assessed using a range of data ambient air monitoring, stack testing, groundwater monitoring and sediment and shell fish monitoring. In particular the ambient air monitoring data was used to calculate the THI and to assess dust exposure however difficult to assess health risk from dust exposure as PM10 was not measured separately
Stack emissions data was used to model the concentration of OCPs expected to be deposited at the off Site air monitoring locations. Found to not be good correlation probably due to the fact there would also be OCPs leaving the Site as fugitive emissions (especially dust) and that conditions during stack testing may have been different from the overall normal operating conditions of the plant. Things that could vary were the temperature of dryer, and the concentration of OCPs in the soil being processed. (Evidence for this)
Modelling was also done as part of the public health investigation to assess possible exposure to dioxins. Many assumptions and uncertainties in this modelling due to very limited data to use as basis for modelling stack testing high result during PoP trials but then not tested again until well after period of most concern about high dryer temps and poorly/non functioning AECS. PRP advice/request not acted on for over a year.
14Prevailing winds and location of monitoring stationsConclusionsRisk if Site left unremediatedOCP exposure - soil and marine environmentOCPs reduced to acceptable levels in soilPublic health risk resulting from remediationLow negligible for a few chemicals during remediationLow and manageable for a few chemicals post remediationUnknown for a few chemicals expert advice recommended on further environmental/biological testing Noise and vibration nuisance/irritation
15Leaving the Mapua site in its contaminated state had been assessed as a significant risk to the environment and public health, particularly because of the organochlorines (OCPs) remaining in the soil, groundwater and marine environment.The remediation has been successful in reducing the OCP in soil to acceptable levels and largely successful in reducing concentrations in marine sediments.The remediation also created some public health risks which have mostly been assessed as low, or negligible. However as there were information gaps on a few of the chemicals of concern that remain, specific recommendations have been made to get expert advice on whether further environmental and/or biological testing should be undertaken.Public Health Risk During RemediationContaminantExposureHealth RiskPM10(Likely) numerous(Likely) low-mediumAmmonia(Likely) low(Likely) very lowDioxins(period of concern Nov 04-March 06)ProbableUnknownPCBs (non-dioxin like)PossibleUnknownBenzenePossibleUnknownOCPs, arsenicLow (north and west of Site)Possible (south of Site)NegligibleUnknownOCPs groundwaterDrinking water UnlikelyIrrigation - PossibleNegligibleUnknownOCPs shellfishUnlikely (notices in place)Negligible(notices in place)16There is considerable uncertainty as to the number of days that the public were exposed to PM10 levels that breached the National Environment Standard as this was not measured and has had to be estimated at least 33 breaches in 33 months. In addition the location of the Tahi Street monitoring sampler is likely to have under represented exposure of people living south of the Site in a similar manner to deposition of OCPs. Therefore it is likely that the standard was breached on numerous occasions (probably similar to what people living in Richmond or Airshed A or B in Nelson are exposed to), leading to an increased risk of adverse health effects, particularly respiratory complaints such as cough, worsening of asthma and increased incidence of bronchitis.Go through remainder brieflyFor dioxins. As already discussed dioxins were not part of the regular monitoring programme and modelling was done as part of the public health investigation to attempt to assess exposure and health risk. Although there appears to be a wide margin of safety in the level of exposure modelled various uncertainties in the limited data available for the modelling and in the assumptions used mean that I have recommended expert advice is sought on further testing.
Public Health Risk Post Remediation
ContaminantExposureHealth RiskAmmonia in soil on SiteUnlikelySite tests show very low levelsOCPs in soil on Site
Possible for DDX (await testing)Uncertain (await testing)OCPs groundwaterDrinking water UnlikelyIrrigation - PossibleNegligibleUnknownOCPs shellfishUnlikely if advisory notices in placeNegligible if notices in place17Go through brieflyChallengesComplexity of the scienceMissing historical dataLack of / poor quality monitoring dataIncomplete temperature records for dryerCommunity concern - keeping them informedRange of agencies involved in investigationCraig18Lessons learned for future similar projects
Have flexible approach recognise may need to adaptShould have Peer Review Panel to oversee project with appropriate range of skills for the projectMedical Officer of Health or representative should be on panelBe aware of potential and risk from fugitive emissions when remediation site is in residential areaRobust Proof of Performance testing under normal operating and site conditionsA statutory review condition in all consents that includes: Reviewing monitoring requirements 19The recommendations for future projects similar in complexity are thatRead from slide:PRPMOH or rep be on the PRP to ensure protection of PH included in deliberations of panel this project has shown the need for a strong voice concerned with human health riskWhen planning such projects the potential for fugitive emissions should be considered with either detailed attention to management options for these emissions or off site remediationPOP testing should be done under normal operating and site conditionsThat a statutory review condition in all consents.. AcknowledgementsMy colleagues at Nelson Marlborough DHB Public Health Service: Dr Ed Kiddle and Geoff CameronDr Deborah Read, Ministry of HealthCraig20