Edmonds UNOCAL / Chevron Cleanup

UNOCAL EDMONDS BULK FUEL TERMINAL SITE Public Participation Grant No. G0800139 (2007-2009) to Edmonds Citizens’ Awareness Committee, Brackett’s Landing Foundation PPG PROJECT EVALUATION REPORT

UNOCAL EDMONDS SITE

UNOCAL operated a Bulk Fuel Terminal in Edmonds, Washington from 1923 to 1991.  In addition to the large volumes of various fuels handled at this site for almost 70 years, an asphalt plant was also in operation at the site for about 20 years.  The site is located near Puget Sound, adjacent to Willow Creek and the Edmonds Marsh.  A fish hatchery is also located at the southeast corner of the property.

The UNOCAL Edmonds site includes an Upper Yard where storage tanks and distribution piping were located and a Lower Yard with offices, rail and truck loading facilities, the asphalt plant and associated warehouse, and storm water handling facilities (Detention Basins 1 and 2).  After extensive excavation of contaminated soils, the Upper Yard was sold and is now a residential condominium development.  The Lower Yard has been identified for use as a multimodal transportation hub, including relocation of the Edmonds ferry.  A purchase and sale agreement for the Lower Yard has been completed between UNOCAL (since purchased by Chevron) and the Washington State Department of Transportation (WSDOT).

Site characterization studies of the Lower Yard documented extensive contamination of soils and ground water with TPH and related contaminants.  Floating product (LNAPLs) was also detected at multiple wells over large portions of the Lower Yard.  After early attempts to recover LNAPLs, a series of Interim Actions began in 2001 and included excavation and removal of contaminated soils, removal and treatment of contaminated ground water, and product removal in localized areas of the Lower Yard.  The large Detention Basin 1 was also dewatered and cleaned out.  During 2007-2008 an extensive Interim Action covering most of the Lower Yard was undertaken, intended by Chevron to complete active site remediation.  A post-Interim Action two-year ground water monitoring program started in October 2008.  Ground water chemistry is being monitored at 40 wells to track compliance with ground water cleanup levels at the property boundary (the MTCA point of compliance), determine if remaining ground water contamination within the Lower Yard is naturally attenuating, detect any re-occurrence of LNAPLs, and determine if residual soil contamination will adversely affect ground water quality.

PUBLIC PARTICIPATION GRANT HISTORY

Reflecting community interest and concerns regarding cleanup of the UNOCAL Terminal Site, the Brackett's Landing Foundation established the Edmonds Citizens' Awareness Committee (ECAC) to support citizen involvement in the cleanup process.  Brackett's Landing Foundation has applied for and received a series of Public Participation Grants from Ecology, starting in 1995.  Those grants have allowed ECAC to hire its own technical consultants to review site information, provide technical review comments to Ecology, and help educate the community about site contamination issues.  The grants have also supported citizen participation in the extended MTCA cleanup process, so that Ecology can take community interests into account.

The formal cleanup process at the UNOCAL Edmonds site started in 1993 when Ecology and UNOCAL signed an Agreed Order for completion of a Remedial Investigation and Feasibility Study.  The time needed to complete site cleanup has far exceeded what was foreseen when ECAC received its first grant in 1995.  Ecology has provided ongoing community support through continuation grants as the cleanup process has been repeatedly extended.  Whether the 2007-2008 Interim Actions successfully completed active remediation, or whether even more remediation is needed, will be determined based on evaluations of the current two-year ground water monitoring program.  ECAC has applied for a continuation grant for 2009-2011 to continue oversight of this monitoring program and data evaluations and support community education and participation through final site cleanup.

CURRENT GRANT ACTIVITIES

Monitoring of Site Cleanup.  Mobilization for starting the Lower Yard Interim Actions took place in July 2007.  Given the relatively late seasonal start for cleanup activities, and in order to maximize work during favorable weather, a public comment period was held concurrently with the start of the Interim Actions.  Remedial actions were completed by September 2008 with installation of a large number of new ground water monitoring wells in preparation for a two-year monitoring program.  Throughout both Phase I and Phase II of the Interim Actions, ECAC made site visits approximately weekly to observe cleanup activities, identify issues needing resolution, and report to the community on progress through blog postings.  Our technical consultant provided a cumulative site visits log to ECAC throughout the cleanup process to reflect site status.  ECAC participated in several oversight visits by Ecology’s site manager.  After completion of Phase I, ECAC’s technical consultant met with ARCADIS’ staff at the Lower Yard to identify locations for collecting additional site characterization information to address data gaps.  As analytical results became available from sidewall and floor sampling at soil excavations, ECAC reviewed those results and discussed them with ARCADIS’ staff during frequent site visits.

Review of Site Reports.  Near the end of the previous grant period, in May/June 2007, a final Interim Action work plan was in preparation.  Ecology and UNOCAL/Chevron negotiated a new Agreed Order to cover additional Lower Yard cleanup activities.  At the start of the current 2007-2009 grant period, ECAC submitted written comments to Ecology during the public comment period on the Interim Action plans as well as the Remedial Investigation/Supplemental Remedial Investigation and new Agreed Order.  ECAC had been an invited participant in a series of meetings among Ecology, UNOCAL/Chevron, and stakeholders leading up to the public comment period.  Several recommendations by ECAC were adopted into the Interim Action work plans.

Lower Yard cleanup actions during the 2007-2008 Interim Actions were documented in two As-Built Reports by Chevron, corresponding to the two phases of remediation.  ECAC submitted written review comments to Ecology on the Phase I As-Built Report (January 8, 2009) on February 12, 2009.  Comments on the Phase II As-Built Report (May 13, 2009) will be submitted by August 2009, in the next grant period.

During development of the Interim Action work plans, ECAC reviewed all site information to identify possible data gaps and made a presentation on that issue to the working group.  Decisions on data gaps requiring additional investigation were deferred at that time pending completion of Interim Action soil excavations, which were deemed likely to expand somewhat beyond planned excavation areas based on field observations and sidewall sampling.  After completion of Phase I of the Interim Actions, Chevron prepared a report titled “Evaluation of Lower Yard Phase I Data and Work Plan for Additional Site Investigation” (May 30, 2008).  ECAC submitted comments on that work plan to Ecology on June 11, 2008 and recommended three additional data gap areas where further site characterization was warranted.  Additional information was collected in two of those three areas; at one, the former asphalt warehouse, additional soil excavations were performed.  At the third recommended area, the former slops pond, no additional information was collected.  A new ground water monitoring well (MW-510) was installed and has shown the highest TPH contamination of any of the 40 monitoring wells currently being sampled.

Chevron submitted a report titled “2008 Additional Site Investigation and Groundwater Monitoring Report” (March 27, 2009) that documented the findings of the additional site characterization investigations after completing Phase I of the Interim Actions, and also summarized the data from the first 2 of 12 planned rounds of post-Interim Action ground water monitoring.  This report included an evaluation of the residual contamination near the WSDOT storm drain line in the Lower Yard which was not removed during the Interim Actions.  ECAC submitted comments on this report to Ecology on April 23, 2009.

Meetings.  ECAC met periodically with its technical consultant to discuss the status of site cleanup activities, evaluations of recent sampling results, and plans for community updates via the weblog.  Ecology, Chevron and its consultant ARCADIS, and ECAC, along with WSDOT, continued the cooperative approach established earlier through the Technical Work Group to identify and discuss issues as they arose.  ECAC participated in a stakeholders meeting in Edmonds on March 12, 2008 at which ARCADIS presented an overview of Phase I of the Interim Actions.  After review comments on the Phase I As-Built Report were compiled, ECAC participated in a meeting at ARCADIS’ offices on March 17, 2009 to discuss the review comments and agree upon report revisions.

Long-Term Ground Water Monitoring Program Data Reviews.  The post-Interim Action two-year ground water monitoring program started with round 1 sampling in October 2008.  A total of 40 wells are being sampled and analyzed each round, with additional wells observed for ground water elevations and product occurrence.  During the current grant period results from the first 4 of 12 planned rounds of sampling were reported by Chevron (as attachments to monthly progress reports to Ecology).  Chevron is to submit detailed ground water data evaluation reports to Ecology at the end of Year 1 and Year 2.  ECAC reviewed the results from each round as they were reported, and started looking at within-well trends as of round 4.  Multiple wells continue to show TPH concentrations above the ground water cleanup levels, many within the perimeter point-of-compliance well system.  The analytical lab performing ground water analyses was changed after round 2 to achieve lower detection limits.  ECAC has called attention to the fact that the TPH type designation changed at several wells after this change in analytical laboratory.  Ground water cleanup levels are affected by the type(s) of TPH detected; this issue will need to be addressed as part of future ground water data evaluations.  In addition to the perimeter compliance monitoring wells, additional wells in the interior of the Lower Yard are being sampled to track changes at several historically-defined “plumes” of TPH contamination.  The data through round 4 are generally not consistent with the spatial continuity assumed for ground water contaminant plumes for two of the three sets of interior wells.  Future evaluations of natural attenuation processes may have to take that pattern into account and focus on within-well evaluations.

Weblog.  During the current grant period ECAC established a website ( HYPERLINK "http://www.ecac-unocal.org" www.ecac-unocal.org) as a primary means of keeping the community informed about the status of site cleanup, issues needing resolution, and opportunities to participate and comment on the overall cleanup process.  As of the end of the current grant period there have been several thousand hits on this blog site.  Biographies of key ECAC officers and consultants and a series of historic site photos are posted on the blog.  Periodic postings kept the community up to date on the Interim Action site remediation activities and the results for each round of post-Interim Action ground water monitoring.  Time trend charts of TPH concentrations at selected wells were included in the posting after round 4 sampling as a means of allowing citizens to easily visualize current conditions at the Lower Yard.  Copies of ECAC written comments submitted to Ecology on reports submitted by Chevron are also being posted on the blog.

SITE STATUS AS OF JUNE 30, 2009

Attempts at floating product (LNAPLs) recovery in the Lower Yard date back to 1987.  After a series of more limited and localized cleanup actions, the 2007-2008 Interim Actions completed an extensive excavation program to remove contaminated soils, while also removing free product and removing and treating a large quantity of contaminated ground water during excavation dewatering.  The excavation areas and volumes of soils removed were considerably larger than identified during planning of the Interim Actions, based on site characterization information.  Buried drums with product and assorted debris were found buried in the southeast Lower Yard, an area without significant historic operations associated with Bulk Fuel Terminal operations. 

 

Some TPH-contaminated soils remain in the Lower Yard, including soils with TPH below the selected remediation level of 2,975 ppm, a few locations with TPH levels marginally above that remediation level, and more substantially contaminated soils near the WSDOT storm drain line.  It is also possible that one or more areas with elevated TPH concentrations have not yet been detected (as substantial portions of the southeast Lower Yard were not identified before excavations began).

No continuing pump-and-treat ground water remediation system has been included as part of the planned Lower Yard cleanup program.  A system of 40 ground water monitoring wells, including both perimeter compliance wells and interior natural attenuation monitoring wells, has been established for ongoing sampling and analysis of ground water quality.  A two-year ground water monitoring program is about one-third completed as of June 30, 2009.  Through the first four rounds of sampling, a substantial fraction of the wells have shown TPH concentrations above the preliminary ground water cleanup levels (based on assumed TPH component types).  Except for one well at the former slops pond location (MW-510), with very high and increasing TPH levels, the TPH concentrations are well below historic levels from mid-1990s sampling during the Remedial Investigation.

Data from the ground water monitoring program will be evaluated after Year 1 and Year 2 sampling are completed to determine if remaining TPH contamination will naturally attenuate and if cleanup levels are attained at the point of compliance wells (property boundary).  If further cleanup actions are deemed necessary based on those evaluations, or if product is detected in the monitoring wells, a Feasibility Study will be prepared to evaluate alternative actions (e.g., further excavations or ground water treatment).  If no further cleanup actions are needed, a Cleanup Action Plan documenting the Interim Actions as final cleanup actions will be prepared.

With further PPG support from Ecology, ECAC intends to continue to review all ground water monitoring data and evaluations and continue to inform the community and encourage citizen participation in the cleanup process.

7558 Brooklyn Avenue NE

GREGORY L. GLASS Seattle, Washington  98115

Environmental Consultant tel:  (206) 523-1858

______________________________________________________________________________

MEMORANDUM

TO: David South, Ecology/NWRO

SUBJECT: Technical Review Comments, Phase II As-Built Report (May 13, 2009)

UNOCAL Edmonds Site

DATE: July 21, 2009

I have reviewed the Phase II As-Built Report (May 13, 2009).  It effectively documents the second-half cleanup activities at the UNOCAL Edmonds site through Fall 2008.  On behalf of ECAC, I am submitting the following technical review comments.  Please contact me if you have any questions or if further discussions would be useful.

Page 15, Section 4.2.1.1:  the number of steel drums or remnants found in excavation area B1 (18) suggests fairly extensive use of the southeast Lower Yard, where no operational facilities were located, for disposal activities.  Are such steel drums/remnants detectable by surface geophysics (magnetometer)?  To what depth?  If ground water results for southeast Lower Yard wells remain problematic, a survey to detect buried drums that extends past the current treeline may be advisable as a screening investigation.  The extent of contamination uncovered in the southeast Lower Yard may warrant a review of the sediment toxicity test failure in Willow Creek adjacent to this area.

Page 17, Section 4.2.2:  I note that the depth of excavation at area B7, to 5 feet bgs, was not deep enough to address potential slops pond residuals.  While the boring log for MW-510, which was deeper, has no indications of significant contamination being encountered, the subsequent ground water monitoring data strongly indicate residual contamination in this area.

Page 17, Section 4.2.3, second paragraph:  the text states that LNAPL was observed entering the excavation from 2001 backfill material on the east sidewall.  See Figure 4, showing Phase I excavation area B8 to the east.  The text at the top of page 18 identifies sidewall locations removed, which appear to be within the Phase I excavation.  Should the reference to 2001 backfill actually be to 2007 Phase I backfill?  I find it notable that LNAPLs may have entered the Phase II area B8 excavation from clean backfill emplaced just months earlier.  This deserves some additional discussion.

Page 27, Section 7:  the ground water cleanup levels established for the site were based on TPH component data from available ground water monitoring results.  They are best described as interim or default ground water cleanup levels, contingent on TPH composition.  Final cleanup levels will be based on actual TPH composition as measured.  This is important given the changes in TPH composition revealed in the early rounds of the long-term, post-remediation ground water monitoring program.

Page 27, Section 7, second paragraph:  please refer to my comments on the ASI report (comments of April 23, 2009:  Page 12, identification of POC and MNA wells).  The most downgradient wells in the western ground water flow path system are also to be evaluated as POC wells, and MW-509 is also to be evaluated for natural attenuation, as agreed to in our discussions to finalize the Interim Action Work Plan in 2007.  The description of the 40 monitoring wells being sampled therefore should be as follows:  21 POC wells around the perimeter of the Lower Yard, 22 MNA wells including three “plume systems” of 7 wells each plus MW-509, and with 3 wells in both the POC and MNA systems (i.e., 40 = 21 + 22 – 3 “duplicates”).  The symbols on Figure 9 should be revised to show this enumeration of wells.

Page 28, Section 7.1.2:  the summary of well installations in the first paragraph does not account for MW-509 (see Figure 9), which is not in any of the three flow path systems, is not a new POC well, and is not a replacement POC well.  The summation of 20 + 5 + 4 wells equaling the 29 installed wells does not account for the double counting of MW-8R which is a POC replacement well but also is in the western flow path system of wells.  This text should be edited accordingly.  Well MW-509 was installed in the “fourth” LNAPL plume area based on our discussions addressing the final work plans for the Interim Actions, and is to be monitored and evaluated as the other 21 flow path wells are.

Page 28, Section 7.1.2:  the additional monitoring wells continued use of 10-foot screened sections.  Considering the Conceptual Site Model – including horizontal and vertical components of ground water flows, the source(s) and release locations for petroleum contaminants, discharge points to surface water, seasonal water level fluctuations, and so on – could 10-foot screened lengths contribute to some dilution effects for ground water quality as sampled in this manner, biasing the measurements low with respect to possible true impacts on surface water?  If this has been examined and written up previously for this site, please provide a reference.

Page 28, Section 7.1.2:  I note that there are no monitoring wells on the upgradient side (site interior) of the POC wells along the southeast property boundary.  When the long-term, post-Interim Action monitoring well systems were being identified prior to the Interim Actions being performed, the extent of contamination in the southeast Lower Yard was assumed to be less than was actually encountered.  LNAPLs were in fact encountered at excavation area B1, including LNAPLs entering from the upgradient face of the excavation (see page 16).  Depending on further/ongoing ground water monitoring results, the lack of upgradient ground water characterization may be a data gap that needs to be addressed.

Page 29, Section 7.1.2, last paragraph and Section 7.1.3:  the enumeration of wells with respect to collection of soil samples during installation does not address MW-522.  That well appears to have been installed just outside of excavation areas (see Figure 9) and according to the boring log (Appendix J) had a relatively elevated PID reading of 34.2 ppm at the bottom of the boring, with lesser hits above.  No soil samples were taken from the MW-522 boring.  Also, MW-500 and MW-501 both had the notation of slight hydrocarbon-like odor (HCLO) on their boring logs, which could be interpreted as a sign of possible impacts.  Compiling the PID readings and boring log annotations of HCLO versus later ground water chemistry results for TPH (rounds 1 through 4 so far), both indicators during well installations are seen to be variable and imperfect predictors of ground water TPH concentrations.  Nevertheless, it might be useful to at least collect and archive soil samples when elevated PID readings occur or HCLO annotations are made during well installations.

Page 29, Section 7.1.3:  the only notation of “strong HCLO” on well boring logs occurs at MW-129R (Appendix J), and a soil sample for that well showed total TPH of 3,010 ppm.  This correlates well with the post-Interim Action ground water monitoring data for MW-129R, with up to 2,655 ug/L TPH.  The likelihood that the MW-129R boring hit the maximum residual soil contamination in this area is remote.

Page 30, Section 7.1.4:  I note that several wells were redeveloped within about one week prior to the December 2008 round of ground water sampling.  A review of the ground water monitoring results from rounds 1 and 2 shows that TPH concentrations dropped substantially at only two of the seven redeveloped wells (MW-500 and MW-501).  Considering possible future redevelopment actions, perhaps a minimum time delay after redevelopment before sampling should be established as a criterion for the ground water monitoring program.

Page 30 et seq., Section 8 (statistical evaluation):  the statistical evaluation of soils data available from Phase II sampling does not relate to any meaningful spatial unit (e.g., an exposure unit or decision unit) and does not provide a meaningful estimate of an Exposure Point Concentration.  See Figure 7 for disparate areas included in the statistical evaluations of Section 8 (with sampling at the Impacted Stockpile area not shown).  Without a well-defined objective for statistical analysis, these evaluations have limited relevance.  I note that the additional information from Phase II analyses of six samples from monitoring well borings (see Table 6) is not included in the statistical evaluations; the maximum TPH result of 3,010 ppm TPH from MW-129R is higher than the maximum carried forward in the statistical analysis.  As previously noted in my comments on the Phase I As-Built Report, the statistical evaluation of compliance with remediation levels (e.g., soil TPH REL based only on a direct contact scenario) in any case does not address the key question of whether residual soil contamination will cause ongoing ground water quality problems.

Page 34:  The text here says 2,000 tons of contaminated sediments were removed from Willow Creek and 900 tons of clean backfill material was used to restore the creek.  On page 13 the text says original creek topography was restored.  Given the difference in removal and restoration amounts, it is hard to see how the original topography was achieved.  (Could this be a difference in wet/saturated removal amounts versus relatively dry replacement amounts?).  This apparent discrepancy should be explained.

Page 34:  the amount of petroleum impacted soil removed from the Lower Yard is given as 13,759 tons.  This does not appear to match the data provided in Table 2, where the total excavation volume is given as 14,825 tons or 12,825 tons without Willow Creek sediments.  It isn’t clear in either the text on page 34 or in Table 2 how the surficial soils excavated at the asphalt warehouse area that were stockpiled, tested, and then re-used as vadose zone backfill are accounted for – but the text indicates 2 stockpiles were about 250 CY each (see page 20; 500 CY equals 750 tons), which doesn’t seem to resolve the discrepancy in amounts between page 34 text and Table 2.  Table 2 does not include a volume for the approximately 2 feet of additional soil removed at the Impacted Stockpile area (see page 25); could that resolve the apparent discrepancy in volumes of contaminated soils?  That missing volume should probably be added in table 2 in any case.

Page 34:  the last paragraph gives the number of confirmation soil samples collected as 88.  But on page 30 (Section 8.1.1) the statistical analysis data set cites 82 samples, which is the total number included in Table 3.  Is the difference the 6 samples collected during monitoring well installation, as indicated in the well boring logs (Appendix J) and enumerated in Table 6?  If so, it should be noted that the text at the bottom of page 34 does not address the soil REL exceedance in the boring sample at MW-129R.

Table 3:  only one sample with high total TPH results appears to be dominated by TPH-G.  That sample is EX-B1-D-43-4, with TPH-G at 2,000 ppm and TPH-D and TPH-O not detected.  TPH composition will be important for evaluating ground water compliance (as noted elsewhere in these comments), and confidence in the analytical determination of TPH compositions is required. It seems odd that one sample and only one sample from the B1 excavation area would have a dominant TPH-G composition, given the lack of operations in this area and the early date of likely disposal actions.  Assuming the confirmation of the analytical interpretation for TPH composition, can this be explained within the conceptual site model?

Figure 9:  the ground water flow paths as shown do not take into account the influence of the impermeable liner (described in the Phase I As-Built Report; see Figure 10) installed at the southern limit of soil excavations just north of the WSDOT storm drain line.  This feature may be an important consideration for interpreting the results of the ground water monitoring program.  Residual soil contamination near the WSDOT line is at or near the highest levels remaining in the Lower Yard (to the extent currently known).  The liner should be shown on all ground water flow direction figures until it is removed.

Appendix J:  I find it interesting that maximum PID results, and relatively elevated PID measurements, occur at the bottom of the monitoring well borings at a number of locations where wells were installed through clean backfill materials (e.g., MW-512, MW-515, MW-516, MW-520 – and MW-522, apparently just outside of the excavation area).  How do these locations correlate to the locations of elevated residual soil contamination (even if <2,975 ppm TPH, the soil REL) based on confirmational sampling after soil removal?  How many of the locations with elevated residual soil contamination do not have monitoring wells in their vicinity?

Minor edits:

Page 19, Section 4.2.5:  it is worth noting that after the collection of additional samples in this area after Phase I excavations were completed, and before Phase II excavations occurred, the water treatment plant was moved to an area already remediated, providing access to asphalt warehouse area soils.

Page 20 (Section 4.2.5.1) and Table 4:  the text says six samples were collected and analyzed from each of the two stockpiles of asphalt warehouse area soils.  Table 4 provides results for only five samples from each stockpile.  This inconsistency should be resolved.

Page 24, Section 5.2, line 3:  “effected” should be “affected”.

Page 24, Section 5.2, second paragraph:  was the high water mark determined visually (matched to the December 2007 flood event?) or from a 100-year, or similar, flood plain map?

For completeness, it would be good to add a Figure (like Figures 3 through 5) showing the ISP (stockpile area) confirmation samples.

Figure 7:  The box for final excavation quantities at the Railroad Trestle Excavation Area shows 507 CY.  This should be 567 CY (at 1.5 CY per ton; see Table 2 for comparison).

Figure 9:  MW-122 is annotated with “monitoring well was abandoned during the interim action and replaced in October 2008”.  The text does not indicate that MW-122 was abandoned (see Section 7) and the well designation is not given as MW-122R.  Make appropriate changes for consistency.

Appendix A, Figure 2:  The location of the asphalt warehouse as shown is incorrect.

To enlarge double click the image and use your view (magnifier)  to zoom in or out!

LOWER YARD 2007-2008 CLEANUP (INTERIM ACTIONS): LONG-TERM GROUND WATER MONITORING PROGRAM UPDATE, June 2009

By Greg Glass (gglassenviro@comcast.net)

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Preliminary Notes. The second of two reports describing the Interim Action cleanup

activities in the Lower Yard during 2007-2008 was submitted by Chevron to Ecology on

May 13, 2009. That Phase II As-Built Report covers the final soil excavation activities,

Willow Creek sediment remediation and restoration, and the installation of new ground

water monitoring wells. ECAC review comments on the Phase II Report will be

submitted later this summer. The Phase I As-Built Report has been revised in response to

review comments from Ecology, ECAC, and the Washington State Department of

Transportation (WSDOT) and is now Final.

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ECAC submitted comments to Ecology on the recent Chevron report titled “2008

Additional Site Investigation and Groundwater Monitoring Report” (March 27, 2009).

Our comments, submitted on April 23, 2009, are provided in a separate posting.

Chevron’s report summarized the results of “data gaps” soils investigations as well as the

results from the first two rounds of the planned two-year ground water monitoring

program. I note that while we identified a potential data gap for soils characterization at

the former slops pond location, no additional soil samples were collected there. One new

ground water monitoring well was installed in that area (MW-510). One portion of this

recent Chevron report addressed the remaining soil contamination that was not removed

during Lower Yard excavations because of concerns over damaging the large WSDOT

storm drain line that traverses the Lower Yard. Soil TPH concentrations near that line

ranged up to almost 17,000 ppm.

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ECAC’s current Public Participation Grant from Ecology ends on June 30, 2009.

Ecology has notified ECAC that it will be receiving an additional grant for the two-year

period through June 30, 2011. That continuation grant will support continued review and

evaluation of the long-term ground water monitoring results as well as any additional

cleanup actions that may be required. We plan to continue periodic postings to this blog

as a primary means of keeping the community informed of the status of site cleanup

activities and remaining issues.

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Ground Water Monitoring Results. Round 4 sampling of 40 ground water monitoring

wells occurred in April 2009; results have now been submitted to Ecology. Since the

long-term ground water monitoring program started in October 2008 15 wells have had

total TPH concentrations above 1,000 ug/L at some point. In Round 4 there were 9 wells

above that level, with 7 of the 9 around the perimeter of the Lower Yard rather than in the

interior. One well – MW-510, at the location of the former slops pond and along the

western site boundary between Willow Creek and Detention Basin 2 (DB-2) – has shown

steeply increasing TPH concentrations over time. In Round 4 it had a TPH value of

22,930 ug/L, more than 10 times the second highest result and by far the highest single

result in any sampling round.

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After a change in analytical laboratory before the third round of sampling (see the April

2009 posting), the reported dominant type of TPH (gasoline versus diesel) changed at

several west-side perimeter wells. Those changes persisted through Round 4. The mix of

TPH types will affect cleanup levels, so this apparent change in type will need to be

carefully reviewed. So far the earlier “default” cleanup levels for the east and west sides

of the Lower Yard (506 and 706 ug/L, respectively) are just being carried forward in all

reporting and data summaries. I expect this issue will be addressed in the Year 1 ground

water evaluation report early in 2010.

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In general, the TPH concentrations in perimeter wells have been more variable (up and

down at a single well over the repeated rounds of sampling) than the interior wells. The

layout of the interior wells was meant to provide information to track changes in ground

water contaminant “plumes” and residual contamination that could move with ground

water to and beyond the property boundary. For each of three “plumes” the set of

monitoring wells included one upgradient well and six additional wells covering both

downgradient and cross-gradient areas. Conceptually this would support tracking

changes in both space and time as any remaining ground water TPH attenuated naturally.

The cumulative results through Round 4 are not very consistent with the assumption of

spatial “plumes”. For two of the three sets of plume wells TPH has been detected at the

upgradient and far-downgradient wells, but not at any wells in between. Single well

(within-well) data evaluations will always be possible, but it remains to be seen whether

multi-well analyses for spatially-extensive “plumes” (as anticipated in an Ecology

software package for natural attenuation evaluations) will be meaningful.

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One well (MW-20R along the western property boundary) remains a high outlier for

benzene concentration. The level in Round 4 declined somewhat to just below the

benzene cleanup level for ground water. The second highest benzene level was at MW-

510 (slops pond), at less than one-third the MW-20R value.

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The ground water conditions in the Lower Yard can be illustrated using some simple data

visualization plots. These plots are intended for data descriptions and not formal data

evaluations (which are initially scheduled to be provided in Chevron’s Year 1 ground

water monitoring report). The X-axis in these plots is time, reflecting ground water

sampling dates; the Y-axis is total TPH concentrations in ug/L. [Any not-detected results

for component TPHs (e.g., TPH-D or TPH-G) are included in total TPH at one-half the

detection limit. Note that those detection limits changed when the analytical lab changed.

The fractional contribution of not-detected results, and instances of all TPH types being

not-detected, are not identified in these simple plots].

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A few of the wells currently being sampled were installed many years earlier for initial

site investigations. The long term data sets for such wells provide a historic context for

the recent monitoring results. Figure 1 shows time trend plots from 1995 on for three

wells: LM-2, at the northwestern corner of DB-1, MW-104 on the western boundary near

Willow Creek, and MW-136 in the far southeastern corner. All three wells had much

higher TPH concentrations when first sampled in the mid-1990s. Recent results appear

somewhat elevated compared to pre-2007/2008 Interim Actions.

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Short-term trends over the first four rounds of the current two-year monitoring program

can be illustrated using various groupings of wells. [Look for changes in the Y-axis

scales for TPH concentrations].

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Figure 2 shows recent trends for 5 wells along the western property boundary. From

southwest to northeast they are: MW-147, MW-522, MW-20R, MW-104, and MW-518.

Figure 3 shows recent trends for 3 wells in the northern Lower Yard near DB-1 and DB-

2: MW-510 (slops pond well, which has shown the most dramatic upward trend in TPH),

LM-2, and MW-507.

Figure 4 shows recent trends for 5 wells along the southeastern boundary of the Lower

Yard. From northwest to southeast they are: MW-129R, MW-501, MW-500, MW-135,

and MW-136. The Round 1 TPH value of more than 8,000 ug/L at MW-501 is the

highest TPH at any well apart from MW-510 so far.

Figure 5 shows recent trends for selected interior (“plume” monitoring) wells: MW-502,

MW-512, MW-513, and MW-514.

The Round 5 sampling results should be available by mid-August. 

All questions and comments on these blog postings and the status of the UNOCAL Edmonds site are

welcome.

This article is related to April's 2009 ongoing action.

7558 Brooklyn Avenue NE

GREGORY L. GLASS Seattle, Washington  98115

Environmental Consultant tel:  (206) 523-1858

______________________________________________________________________________

MEMORANDUM

TO: David South, Ecology/NWRO

SUBJECT: UNOCAL Edmonds Site

2008 Additional Site Investigation and Groundwater Monitoring Report,

March 27, 2008

Review Comments

DATE: April 23, 2009

I have reviewed the March 27, 2009 report by ARCADIS on Additional Site Investigations during the recent Interim Actions.  On behalf of ECAC I am submitting the following review comments.  Please contact me if you have any questions or would like further discussion on any of these comments.

Technical Comments

Page 6, purposes of the additional site investigations.  I note that the area of the former slops pond was also identified as a data gap, particularly given the lack of any information that the slops pond area had ever been cleaned out during site operations or thereafter.  Information on the installation of one new monitoring well at that area (MW-510), and the results of soil samples collected during installation, will be included in the Phase II As-Built Report.  No additional soil borings were advanced in the area of the slops pond.  I recognize that detailed evaluations of ground water monitoring data will occur in the future.  However, given the ground water monitoring results for MW-510 to date, and the ground water flow direction maps that show flows into the Lower Yard near the slops pond, it seems likely to me that some residual contamination remains at the slops pond location.

Page 7, first full paragraph.  It is worth noting that the available locations for sampling in the vicinity of the former asphalt warehouse after Phase I was completed were constrained by the continued presence of the onsite WWTP for Interim Actions, which covered portions of the asphalt warehouse footprint.

Page 8, SB-80 results.  Soil boring location SB-80 appears to be far enough away from the WSDOT storm drain line that excavations there would not pose risks to the line.  The exceedance of RELs/CULs at SB-80 suggests there is another area of contaminated soils that could have been addressed as part of the Phase II Interim Actions.  An explanation of why it was not should be included, either in this report or the forthcoming Phase II As-Built Report.  (Note that SB-80 is close to MW-143 which had TPH above CULs in the February 2009 ground water sampling round).

Page 9, estimated volume of impacted soils.  There is a considerable interval (up to about 8 feet) between the last (deepest) sample that exceeded soil RELs/CULs and the next sample that did not in the soil borings near the WSDOT storm drain line (see Figure 8).  Was the depth of impacted soil, for the purposes of the volume calculation, assumed to be at the last interval exceeding, the assumed seasonal low ground water elevation, midway between the two adjacent samples bracketing exceedances, or something else?  The basis for the volume calculation should be stated.  (Note that the boring log for SB-66 has a notation of strong hydrocarbon like odor below the last sampled depth interval exceeding RELs/CULs).

Page 10, section 4.3:  asphalt warehouse area and section 4.4:  well MW-129 area.  It is worth noting that the boring logs for SB-76 and SB-78 both indicate that LNAPLs were observed.  Regarding the SB-78 boring log:  what is the “sample bag” referenced in the LNAPL notation?  Soil excavations apparently did not extend to include the SB-78 location near MW-129; the reported soil TPH concentration at the same depth interval where the LNAPL notation occurred was low.  Is there a reason to doubt that the LNAPL notation was accurate?  Given that one objective of the additional soil investigations was to evaluate possible sources of LNAPLs that had been reported historically at MW-129, some additional discussion on the boring log observation at SB-78 is warranted.

Page 11, soil excavations near MW-129 and the former asphalt warehouse.  The text states that the additional soil excavations during Phase II, based on the results of additional site investigations, were extended to include SB-76, SB-77, and SB-79.  (See also page 22).  The locations of the soil borings and the additional soil excavations as shown in the Figures (for example, Figures 4 and 5 versus Figures 11 through 15) do not appear to show excavations extending to SB-77 and SB-79.  Are locations shown accurately on the Figures?  Did soil excavations actually get as close to MW-129 as SB-77 and SB-79?  (I do not recall that they did, but perhaps I am mistaken).  Please review survey information for these locations and revise the text and figures as needed.

Page 12, identification of POC and MNA wells.  The three most downgradient wells in the west MNA system (MW-522, MW-523, MW-8R) are located very nearly on the property boundary.  I noted during our 2007 discussions on the Interim Action work plans that it would be difficult to conclude the site was in compliance with ground water CULs if any of those wells had concentrations above the CULs, given their location.  On that basis I proposed, and I recall we agreed, that all three most downgradient wells in that MNA system would also be evaluated as POC wells.  Only MW-8R is so designated in this report, while also being included as an MNA well.  Wells MW-522 and MW-523 should also be noted as being both POC and MNA wells.  This will increase the total number of POC wells to 21, and the discussions of the October and December 2008 ground water sampling rounds should be updated to reflect this change (e.g., 6 of 21 POC wells exceeded CULs in October 2008).

We also agreed that a single well, MW-509, that is not in any of the three MNA “plumes” would be evaluated for natural attenuation.  Prior to the start of 2007 excavations the maximum observed thickness of LNAPLs occurred in that area, and in lieu of a complete “fourth plume” system we agreed that a single well would be sampled and evaluated there.

The description of the 40 monitoring wells being sampled therefore should be as follows:  21 POC wells around the perimeter of the Lower Yard, 22 MNA wells including three “plume systems” of 7 wells each plus MW-509, and with 3 wells in both the POC and MNA systems (i.e., 40 = 21 + 22 – 3 “duplicates”).

Page 12, CULs.  I understand that detailed evaluation of ground water monitoring data will not occur until later.  I note, however, that the different TPH CULs for the east versus west portions of the Lower Yard were derived based on typical TPH compositions as determined from historic ground water monitoring results.  Final compliance will be based on the actual TPH compositions as measured during the current monitoring program (a matter of some interest given changes in the reported composition for some wells in the February 2009 sampling round).  I recommend that a footnote be added to the two bullets with TPH CULs that says the following:  “Ground water TPH CULs presented here were derived based on historic TPH composition data; final CULs for each POC well will reflect the actual composition of TPH as measured at that well.  All data presentations in this report are based on the default TPH CULs shown here”.

Page 12, statistical analysis of compliance with ground water CULs.  There are likely to be considerations besides a statistical calculation of the mean concentration involved in compliance decisions.  For example, even if the mean (UCL) over all 12 sampling rounds, or the last 6 rounds, meets the CULs, it would be difficult to conclude that ground water is in compliance if there was an increasing trend at a POC well – especially if the last one or two sampling rounds showed exceedance of a CUL.  The CUL to which a statistically calculated mean should be compared should also take into account the variability in TPH composition documented for a well.  Finally, the spatial characteristics of ground water contamination in the interior of the Lower Yard may not be in accordance with the assumption of “plumes” with spatial continuity.  This may affect the applicability of standard approaches to evaluate “plume stability”.  All of these detailed issues related to compliance will be ripe for evaluation as long-term ground water monitoring data are compiled.

Page 13, monitoring well installations.  Please clarify the status of MW-122.  The text identifies a total of 29 wells installed in October 2008, including 25 new “500” series wells and 4 replacement wells:  MW-149R, MW-8R, MW-139R, and MW-129R.  On Figure 11, MW-122 has footnote 1 which states “monitoring well was abandoned during interim action and replaced in October 2008”.  The text in section 4.4 (pages 10-11) which discusses additional investigations in the MW-129 area states that MW-129 was decommissioned and replaced, but does not mention MW-122.  If MW-122 was in fact replaced (perhaps it was so close to MW-129 it had to be abandoned and replaced because MW-129 was being replaced?) the text on page 13 should be updated to reflect 30 well installations.  If not the footnote on Figure 11 should be removed.

Page 15, water levels and ground water flow direction contour mapping.  See also Table 2.  The large, anomalous rise in ground water elevations at MW-500 and MW-501 between October and December 2008, as shown in Table 2, should be noted in the text.  For these wells, the December 2008 measurements are not “consistent with past measurements”.  MW-135, located next to MW-500 and MW-501 in the southeast Lower Yard, showed a significant decrease over these two months and is also not consistent with the general pattern over the entire Lower Yard.   It is questionable whether the December  MW-135 elevation should be used for contouring (see Figure 13).  The general pattern of ground water flow directions would not be markedly affected by the omission of the MW-135 value.  The October 2008 water level at MW-524 also appears anomalous and should be considered for omission for contouring.

Table 5.  The pH at well LM-2 at the northwest corner of DB1 was anomalously low (<4) both in October and December 2008.  Is there any prior pH data for that well that is consistent with such low readings?

Appendix C, ISI Low-Flow Logs.  This appendix presents data as recorded, which is sufficient for this report.  Detailed evaluations are not presented here, but when they are provided (Year 1 and Year 2 annual ground water monitoring reports) a number of items merit discussion and a screening process to delete unacceptable data should be completed.  There are some indications of meter malfunctioning.  The last readings for MW-500 in October, for example, include a temperature of 87.65 degrees F (very unlikely) and a dramatic change within minutes for other parameters.  There are repeated notations that ORP did not stabilize before samples were collected, and cases where only one set of readings was obtained before sampling (see LM-2 in October).  A few wells show high and variable turbidity values (see multiple well records in December), which may indicate a meter problem or a well screen or well development issue (although these wells had much lower turbidity in October).  If these ISI data indicate some potential questions about the field monitoring equipment or the condition of monitoring wells it would be very desirable to address those questions now and take appropriate actions as required, so that high quality data can continue to be collected for later evaluation.

Minor Edits

Page 5, first paragraph.  The statement that the WSDOT storm drain line crosses the Lower Yard at a depth of 9 to 12 feet bgs, given that the line is described as a 72-inch line, is unclear.  Compare to Figure 8, showing the line extending from about 8 to 14 feet bgs.  Is this sentence on page 5 intended to describe the top of drain line elevation as it varies across the site?  Consider rewording the text for clarity, and consistency with Figure 8.

Page 6, third paragraph below bullets.  Change “…in the most southeastern portion of the Lower Yard…” to “…in the most southwestern portion of the Lower Yard…”.

Page 8, first bullet.  Add TPH-O as a listed analyte.  Compare to the third bullet at the top of page 14.

Page 9, bottom paragraph.  Since none of the soil samples collected as part of the additional site investigations near the former railroad trestle area exceeded RELs or CULs, the areas of impacted soils are better characterized as having been “confirmed” by the additional site investigations rather than “identified” by those investigations.

Page 19, fourth bullet.  Change “surrogate percent recovery were…” to “surrogate percent recoveries were…”.