| Action Date |
Action |
Description |
DEC Staff |
| 8/15/2005 |
Update or Other Action |
A DEC Brownfields Assessment Request Form was submitted for this property on this date by the Anchorage Community Land Trust (ACLT). The request is combined with one for the adjacent property known as the Warner Trust Property, located at 3300 Mountain View Drive. The ACLT is interested in redeveloping the property as part of the Mountain View neighborhood revitalization effort. |
Sonja Benson |
| 9/21/2005 |
Site Added to Database |
Brownfield Tracking site. |
Deborah Williams |
| 9/21/2005 |
GIS Position Updated |
Locational data from Topozone.com, NAD 83 from site map in the DEC Brownfields Assessment Request form. |
Deborah Williams |
| 10/25/2005 |
Brownfields Award |
A notice to proceed for a Phase I Environmental Site Assessment was approved on this date. The project will be funded by DEC's State & Tribal Response Program grant from EPA. Confirmation of a site as a brownfield reflects its eligibility for federal brownfield assessment funding, but does not indicate that the site is known to be contaminated with petroleum or a hazardous substance. FY 2006 SOA CIP funds $3,436 and EPA STRP funds $3,436 ($6,872 total project estimate) awarded to Anchorage Community Land Trust for Phase I ESA. |
Sonja Benson |
| 2/21/2006 |
Document, Report, or Work plan Review - other |
DEC received the Phase I Environmental Site Assessment report for the subject site on this date. Two areas of concern were identified and suggested for additional assessment: 1) open drums located to the south of the machine and auto body shops, and 2) a pile of discarded batteries and other waste including partially full containers of antifreeze and other, unlabeled liquids. |
Sonja Benson |
| 4/10/2008 |
Update or Other Action |
The Anchorage Community Development Authority (ACDA) was sent a letter on this date by Contaminated Sites Program Anchorage staff O'Connell stating that DEC does not consider the subject property to be a contaminated site. This determination was based on review of data in a February 2008 Phase II Environmental Site Assessment report submitted by ACDA for the property identified in the report as "Glenn Square Project, 3340 Mountain View Drive."
The Wilhour site will retain listing as an "informational" record to satisfy public tracking requirements stemming from the use of federal brownfield funds for the original Phase I assessment completed in 2006.
|
Sonja Benson |
| 1/13/2014 |
Update or Other Action |
Received notification that additional investigation occurred at the site, and TCE detected above cleanup levels. Drill cuttings were tested for TCLP at levels allowing disposal of material at Anchorage landfill. |
John Carnahan |
| 1/21/2014 |
Meeting or Teleconference Held |
Meeting with AHFC, CIHA and Glenn Gellert to discuss the status of the project and proposed actions that may be necessary to pursue development of site, based on the October 2013 limited assessment report. |
John Carnahan |
| 2/3/2014 |
Update or Other Action |
Change project manager to Anchorage staff. |
John Carnahan |
| 3/4/2014 |
Document, Report, or Work plan Review - other |
ADEC sent comments on the draft Potential Contaminated Soil Management Plan. |
Meghan Dooley |
| 5/2/2014 |
Document, Report, or Work plan Review - other |
ADEC approved the Final Potential Contaminated Soil Management Work Plan. The plan proposes two options for soil management: stockpile sampling following removal or precharacterization of soils in-situ. Soil meeting cleanup levels may be beneficially reused on site. Soils exceeding cleanup levels will be taken to ASR or the Anchorage Municipal landfill. Confirmation samples will be collected from below buidling excavation footprints in order to document contamination being left in place. |
Meghan Dooley |
| 7/1/2014 |
Site Visit |
ADEC staff conducted a site visit to observe the installation of nested groundwater monitoring wells downgradient of the source area. |
Meghan Dooley |
| 7/9/2014 |
Document, Report, or Work plan Review - other |
ADEC recieved the Soils Characterization Report. The purpose of the report was to investigate potential contamination at the site and determine proper method for managing potentially contaminated soils during the construction phase of the redevelopment project. 140 soil borings were advanced to depths ranging from 2-14' below ground surface. Field screening samples were collected at each boring, and 76 samples were selected and submitted to the laboratory for analysis based on field screening results. TCE was reported exceeding cleanup leves at 13 locations with concentrations ranging from 0.0268 mg/kg to 2.29 mg/kg. DRO was encountered above cleanup levels in three samples, ranging from 1,760 mg/kg to 3,840 mg/kg. RRO was encountered in one sample exceeding cleanup levels at 10,900 mg/kg. |
Meghan Dooley |
| 9/3/2014 |
Document, Report, or Work plan Review - other |
ADEC received the Groundwater Monitoring Report. Eight wells were installed as four sets of nested wells onsite and at downgradient locations offsite. Soil samples were collected from the soil borings and TCE was detected above cleanup levels at MW7-18 and MW7B-27 at concentrations of 0.0260 and 0.0912 mg/kg, respectively. Groundwater samples were collected at all new and existing wells and TCE was detected above cleanup levels at wells MW-1, MW-2, and new well MW-7B at concentrations of 0.0231, 0.0222, and 0.0171 mg/L. |
Meghan Dooley |
| 9/15/2014 |
Site Visit |
ADEC staff conducted a site visit to observe the excavation activities. A water line and concrete slab were encountered during the excavation. The slab was removed and will be disposed of at the landfill pending ARL approval. |
Meghan Dooley |
| 10/24/2014 |
Site Visit |
ADEC conducted a site visit to observe the vapor barrier installation and testing. |
Meghan Dooley |
| 3/16/2016 |
Document, Report, or Work plan Review - other |
Two sampling events took place on the property in 2015. In February 2015 monitoring wells MW1, MW2, and MW7B exceeded ADEC cleanup levels for Trichloroethylene (TCE) with concentrations up to 0.0192 mg/L in MW2. Chloroform and 1,1,1-Trichloroethane were detected in several monitoring wells, but were below ADEC cleanup levels. In July and August 2015 additional sampling was conducted. TCE exceeded ADEC cleanup standards in monitoring wells MW1, MW2 and MW7B with concentrations up to 0.0271 mg/L in MW2. 1,1,1-Trichloroethane was detected in monitoring well MW6B but was below ADEC cleanup levels. |
Chelsy Passmore |
| 2/24/2017 |
Document, Report, or Work plan Review - other |
Reviewed “February 2016 Groundwater Monitoring Activities Report” dated February 2017. In February 2016 the consultant mobilized to the subject property and sampled the 10 onsite monitoring wells. Wells MW-6 and MW-7 are nested pairs, enabling sampling at different depths. Groundwater exceeded the ADEC TCE cleanup level of 0.0028 mg/L in monitoring wells MW-1, MW-2, MW-7, MW-7B, and MW-6. Concentrations in MW-1 and MW-2 were highest with concentrations of 0.0155 mg/L and 0.0154 mg/L respectively. Concentrations in MW-6, MW7 and MW7B ranged from 0.00317 mg/L to 0.00633 mg/L. Approximate groundwater flow is to the west. |
Chelsy Passmore |
| 2/1/2018 |
Update or Other Action |
File number was changed from 2100.57.003 to 2100.38.569 to reflect the site's status as not currently receiving Brownfield's Grant money. |
Chelsy Passmore |
| 6/15/2018 |
Site Characterization Report Approved |
The ADEC Reviewed the Site Characterization Activities report. Five passive soil gas samples were collected and analyzed for VOCs. All soil gas samples contained benzene which ranged from 44-289 ng. Xylenes were detected in SPG2, SPG4, and SPG5 from 30-131 ng, and 1,2,4-trimethlybenzene, and 1,3,5-trimethylbenzene were detected in SPG5 at 183 ng and 63 ng respectively. In addition TPH C4-C9 and TPH C10-C15 were detected in SPG4 and SPG5 up to 29,623, and 6,239 ng respectively.
Eight analytical soil samples including one duplicate were collected from 3 soil borings. PCE was detected in boring B8 at approximately 25-26.5 feet bgs, and in boring B9 at approximately 32.5 to 39.5 feet at levels up to 99.7 ug/kg below the ADEC cleanup level. 1,2,3- trichloropropane, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, and naphthalene were detected above ADEC Migration to Groundwater (MTGW) cleanup levels but below Human Health Cleanup Levels in sample B8S0 at approximately 5-8 feet. In addition it was reported that samples B8S0 and B8S7 smelled of hydrocarbons, and ADEC requested that samples be analyzed for GRO, DRO, and RRO. Both samples contained GRO, DRO, and RRO. Sample B8S0 did not contain petroleum analytes above the ADEC MTGW, however sample B8S7 at 35-37 feet bgs contained DRO up to 1,080 mg/kg, above the ADEC MTGW cleanup level.
Three soil borings were completed as monitoring wells, during this sampling event, then sampled in addition to 5 additional monitoring wells on the site. MW-9 could not be located during this sampling event and was not sampled. Nine groundwater samples including one duplicate were collected during the sampling event. MW-1, MW-2, and MW7b contained TCE above ADEC cleanup levels at concentrations ranging from to 4.68 to 12.1 ug/L |
Chelsy Passmore |
| 6/15/2018 |
Site Characterization Report Approved |
The ADEC Reviewed the Site Characterization Activities report. Five passive soil gas samples were collected and analyzed for VOCs. All soil gas samples contained benzene which ranged from 44-289 ng. Xylenes were detected in SPG2, SPG4, and SPG5 from 30-131 ng, and 1,2,4-trimethlybenzene, and 1,3,5-trimethylbenzene were detected in SPG5 at 183 ng and 63 ng respectively. In addition TPH C4-C9 and TPH C10-C15 were detected in SPG4 and SPG5 up to 29,623, and 6,239 ng respectively.
Eight analytical soil samples including one duplicate were collected from 3 soil borings. PCE was detected in boring B8 at approximately 25-26.5 feet bgs, and in boring B9 at approximately 32.5 to 39.5 feet at levels up to 99.7 ug/kg below the ADEC cleanup level. 1,2,3- trichloropropane, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, and naphthalene were detected above ADEC Migration to Groundwater (MTGW) cleanup levels but below Human Health Cleanup Levels in sample B8S0 at approximately 5-8 feet. In addition it was reported that samples B8S0 and B8S7 smelled of hydrocarbons, and ADEC requested that samples be analyzed for GRO, DRO, and RRO. Both samples contained GRO, DRO, and RRO. Sample B8S0 did not contain petroleum analytes above the ADEC MTGW, however sample B8S7 at 35-37 feet bgs contained DRO up to 1,080 mg/kg, above the ADEC MTGW cleanup level.
Three soil borings were completed as monitoring wells, during this sampling event, then sampled in addition to 5 additional monitoring wells on the site. MW-9 could not be located during this sampling event and was not sampled. Nine groundwater samples including one duplicate were collected during the sampling event. MW-1, MW-2, and MW7b contained TCE above ADEC cleanup levels at concentrations ranging from to 4.68 to 12.1 ug/L |
Chelsy Passmore |
| 7/22/2019 |
Site Characterization Workplan Approved |
The ADEC reviewed the 2019 Wilhour Trust Property Draft Site Characterization Workplan and has no objections to the workplan |
Chelsy Passmore |
| 7/22/2019 |
Site Characterization Workplan Approved |
The ADEC received the final copy of the 2019 Wilhour Trust Property Site Characterization Workplan. |
Chelsy Passmore |
| 1/3/2020 |
Site Characterization Report Approved |
Groundwater samples were collected from MW1,MW2, MW6, MW6B, MW7, MW7B, MW8, MW9 (post development) and MW10. TCE concentrations above ADEC cleanup levels were detected in groundwater samples from MW1 and MW2 up to 10.2 ug/L.
No private drinking water wells were discovered during the 2019 survey.
Four subsurface soil gas points were installed in the Mountain View Drive and Rampart Drive right of way. Concentrations of ethylbenzene exceeded ADEC target levels in Soil Gas Point (SGP) SGP1, SGP2 and SGP12 with concentrations up to 5,900 ug/m^3. Concentrations of benzene and xylenes were detected above ADEC target levels in SGP1, SGP2, and SGP12.
In addition during the advancement of SGP2 petroleum impacted soil was encountedered at approximately nine to 10 feet. Samples collected from soil cutting contained concentrations of DRO, ethylbenzene, 1,2,4-trimethylbenzene, napthalene, and arsenic above ADEC migration to groundwater cleanup levels. |
Chelsy Passmore |
| 8/21/2020 |
Offsite Soil or Groundwater Disposal Approved |
Approved transport request to take approximately 100 gallons of TCE-contaminated purge water to US Ecology for shipment to Idaho. The request was reapproved after the final disposal location was updated. |
Janice Wiegers |
| 11/5/2020 |
Document, Report, or Work plan Review - other |
Sent comments on the Draft 2020 Groundwater Monitoring Event dated October, 2020. |
Jessica Hall |
| 11/5/2020 |
Exposure Tracking Model Ranking |
Initial ranking with ETM completed for source area id: 75117 name: auto-generated pm edit BFT - Wilhour Trust Property |
Jessica Hall |
| 11/12/2020 |
Site Characterization Report Approved |
Reviewed and Approved 2020 GW Monitoring Event Report, dated November 2020 and received by ADEC 11/9/2020. Groundwater sampling occurred August 27 & 28, 2021. |
Jessica Hall |
| 1/20/2021 |
Site Visit |
ADEC/SPAR/CSP Environmental Program Manager was on site to deploy two passive air samplers Ridge S-1 and Ridge S-2. Mod T017 analysis was requested. This sampling was performed to verify if the vapor barrier installed under the foundation is working properly to keep indoor air vapors out of the buildings. |
Jessica Hall |
| 2/3/2021 |
Update or Other Action |
ADEC/SPAR/CSP Program Manager was on site to retrieve the two air samplers Ridge S-1 and Ridge S-2 and sent to eurofins, Air Toxics lab for analysis. |
Jessica Hall |
| 2/18/2021 |
Update or Other Action |
ADEC received result from eurofins, Air Toxics lab. Sample Ridge S-1 sample detected Trichloroethene, Tetrachloroethene, 1,2-Dichloroethane, and Chloroform. Sample Ridgeline S-1 sample Ridge S-2 detected Trichloroethene, Tetrachloroethene, and Chloroform. Trichloroethylene in both samples is elevated above indoor air target levels. ADEC/SPAR/CSP Environmental Program Manager will go back out and do additional indoor air sampling at 146 A&B, 138 E, an additional sample in mechanical/electrical room, and one outdoor sample.
|
Jessica Hall |
| 3/18/2021 |
Site Visit |
ADEC/SPAR/CSP Environmental Program Manager deployed air samplers at the following locations which had the following concentrations of TCE: DID EXCEED CULs-BZ505- Mechanical Room Floor Drain-21 ug/m3, BZ506- Mechanical Room- 23 ug/m3, BZ507-Storage Room- 2.2 ug/m3,BZ508- Unit 138- 18 ug/m3,BZ509- Unit 146A Garage-3.4 ug/m3, BZ510-Unit 146A Second floor-3.0 ug/m3, ,
BZ514-Mechanical Room duplicate of BZ506-21 ug/m3. DID NOT EXCEED CULs-BZ512- Unit 146B Second floor-0.80 mg/m3,BZ513- Outdoor Air Sample-ND, andBZ511-Unit 146B First floor stairs-0.99 ug/m3.
|
Jessica Hall |
| 5/7/2021 |
Update or Other Action |
Air samplers deployed in the following locations: All units in bldg.152 except unit D, an outdoor sampler on the north side of bldg.146, A sampler in unit 138A, All units in bldg.106, 137 & 145,Two samplers in the community bldg., one in a community directors office, and one in the breakroom. Located the vapor vent “stub-up’s in bldg’s 146, 138, 106 & 145 and took PID readings inside the pipe. It is believed that the stub-up on bldg.152 was found, but it was enclosed in a sheetrock enclosure. It wasn’t evident where the stub-up was for bldg.137, but based on the other buildings. CIHA is planning on meeting at the development on Friday 5/7/21 at 9AM to retrieve the samplers.
|
Jessica Hall |
| 5/14/2021 |
Update or Other Action |
The results of the May 5-7, 2021, sampling event findings:•Building 152 units were repeated. The one unit (152C) that had detectable concentrations of TCE came back slightly lower this time. •138A was re-sampled since the residents did not move out. CIHA had placed two air purification units in the apartment. The concentration of TCE decreased from 24 ug/m3 to 15 ug/m3. CIHA is moving forward with mitigation of the 138 units. •All samples from the 137 and 145 buildings were non-detect at a laboratory reporting limit of 0.52 ug/m3. No further sampling is recommended for these units at this time.
•Only one unit (106A) in Building 106 had detectable concentrations of TCE. The concentration in the garage (6.8 ug/m3) exceeded. The presence of a possible background source will be evalauted. Diagnostic testing was performed in buildings 138 and 145 to evaluate the feasibility of sub-slab depressurization (SSD) and gather data (vacuum, flow, and radius of influence) for design considerations. Preliminary results suggest that SSD should be effective.
|
Jessica Hall |
| 5/14/2021 |
Update or Other Action |
Health Assessor/State of Alaska Department of Health and Social Services
Environmental Public Health Program advised it would be fine if the occupants of building 152 moved back in. They think that building should also get a mitigation system since there is some detectable TCE. To be safe, all the units should have a mitigation system if possible.
They suggested to sample building 129 since it hasn’t been sampled yet. They consulted with staff at ATSDR this morning about these latest results and they re-iterated that.
|
Jessica Hall |
| 5/19/2021 |
Update or Other Action |
Last week CIHA conducted diagnostics on buildings 146 & 138 and confirmed that plan to mechanically exhaust the vapors under the building slab to the outside above the roofs will work. Geosyntec provided CIHA a design for the mechanical exhaust system CIH plans to install it on buildings 138, 146 & 152. CIHA is currently procuring some of the materials that will be needed and plan start the installation as soon as everything is procured.
Next week Geosyntec will be investigating unit 106A to see if they can identify a background source for the elevated TCE levels that the sampling revealed. Geosyntec is proposing to use a “frog 4000” device that is calibrated for TCE to be used on the investigation of unit 106A. Based on what is found, next steps will be determined for that unit/building and will also guide what thoughts are for testing of building 129.
|
Jessica Hall |
| 6/18/2021 |
Update or Other Action |
The testing results for unit 129 E, were all non-detect. Did not test unit 129 D. Based on the test non-detect results from 129 E and the non-Detect results for all units in buildings 137 & 145 immediately to the south of building 129. No clear need to test additional units in building 129. CIHA is wrapping up the installation of the mechanical mitigation systems for buildings 152, 146, 138 & 106 and will be done June 18, 2021.
June 21, 2021, Monday afternoon to samplers will be deployed in units 152 C, 106 A and all units in buildings 138 & 146 (the 4 buildings with active mechanical mitigation).
|
Jessica Hall |
| 7/8/2021 |
Update or Other Action |
After installing the mitigation systems on buildings 152, 146, 138 & 106, letting them run for two weeks and re-testing recently indicated a decrease in TCE concentrations however 2 units that have sample results higher than ADEC’s action limit of 2.0. Unit 138E had a 2.2 reading and unit 146E had a reading of 2.9 in the garage. All other units tested were below the ADEC action limit.
Additional investigation performed today by Geosyntec/CIH in buildings 146 & 138 to see if the mitigation systems in those living units that had results higher than 2.0 are working as designed.
Replacing the exhaust fans with more powerful fans has not been ruled out, but the additional investigation will be done first. Re-testing the units that have readings above 2.0 next week.
ADEC has no objections to tenants reentering homes that are now below the TCE action level. |
Jessica Hall |
| 7/21/2021 |
Update or Other Action |
Testing was done in units 106A, 138A,C & E, 146A,C & E. Units 106A and 138E are now below the ADEC action limit of 2.0.
There are still a couple units in building 146 with levels above the ADEC action limit (146C & E), which are both in the garages. After CIH discussed this with Geosyntec, the recommendation is to install bigger fans on buildings 138 & 146 and do another round of testing. CIH is ordering fans today and the goal is to have them installed by the end of the week and let them run over the weekend. It is expected to test units early next week and have results toward the end of next week. |
Jessica Hall |
| 8/25/2021 |
Update or Other Action |
CIHA and Geosyntec identified the sanitary sewer penetrations as likely VI conduits in the units where exceedances are occurring after the sub slab system was turned on. They are planning on re-sealing those penetrations next week then resampling. |
Jessica Hall |
| 9/20/2021 |
Update or Other Action |
The latest testing results for 146 C & E are as follows, 146 C the results were 0.41 ug/m3 upstairs and 1.2 ug/m3 in the garage and in 146 E the upstairs was 0.52 ug/m3 and 0.95 ug/m3 in the garage.
Previous testing was specific to the pipe penetrations through the floor slab in these particular units and the results showed that vapor intrusion was occurring around the pipe penetrations. Sealed around all of the slab penetrations in 146 C, D & E. Although previously results were below ADEC action limit of 2.0 ug/m3 in 146 D, it was unoccupied so all the penetrations while no one was living there as an additional precaution were sealed. Earlier testing results in units 146 A & B indicated results below ADEC’s action limit of 2.0 ug/m3, however sealing is planned for all the pipe penetrations in 146 A & B as well.
As an additional measure there are plans to install a device in the garage floor drains of building 146 that allows water to enter the drain, but it seals out the odors that can be associated with infrequently used drains. This is simply an additional low cost measure to mitigate potential vapor intrusion at the floor drains.
A remote alarm system was installed on the four fans on buildings 106, 138, 146 & 152 so in the event that a fan shuts off for some reason, it notifies four CIHA staff with an email and text that the fan is off in that particular building. The four CIHA staff that are notified are the Maintenance Manager, and the Maintenance Supervisors. The fans also have an audible alarm as well that can be heard on site.
Based on these most recent results, ADEC approved to move residents back into units 146 C & D. |
Jessica Hall |
| 10/13/2021 |
Update or Other Action |
CIHA, ACAH and Geosyntec have discussed moving into long-term performance monitoring of mitigation. Geosyntec will soon begin preparing a summary report of assessment and mitigation performed from April 2021 to September 2021.
Future Sampling: will include performance verification by sampling indoor air annually in limited units to confirm mitigation continues to maintain TCE concentrations below the indoor air target level. The performance sampling will begin in 2022 with testing also occurring in 2023 and 2024. The performance sampling will be done during the winter heating season. The sampling in 2022 will target units where earlier assessments showed concentrations above the target level, but limited sampling has occurred since mitigation began. Anticipate sampling six units in early 2022, including one unit each in Building 106 and 152 as a final confirmation for these buildings on the perimeter of influence from residual TCE and two units in Buildings 138 and 146. For 2023 and 2024, two units will be targeted in Buildings 138 and 146. In addition to the sampling, the plan also will include 1) routine assessment and safety checks for the mitigation fans, 2) assessment of units for structural or maintenance issues that could affect vapor intrusion during required building inspections that we perform for other purposes or during temporary vacancies, and 3) a contingency plan should test results or other assessment findings indicate that mitigation is not meeting the performance goal.
|
Jessica Hall |
| 12/3/2021 |
Meeting or Teleconference Held |
Meeting with ADEC supervisor, EPS, and Alaska Department of Health and Social Services to review ADEC comments prepared for Draft Vapor Intrusion Summary Report, dated November 2021. |
Jessica Hall |
| 12/7/2021 |
Document, Report, or Work plan Review - other |
Sent comments from review of Draft Vapor Intrusion Summary Report, dated November 2021 to CIH (RP). |
Jessica Hall |
| 12/7/2021 |
Exposure Tracking Model Ranking |
A new updated ranking with ETM has been completed for source area 75117 auto-generated pm edit BFT - Wilhour Trust Property. |
Jessica Hall |
| 12/14/2021 |
Update or Other Action |
Received response to questions for draft VI Summary Report from CIH and place them in the site file. |
Jessica Hall |
| 1/25/2022 |
Document, Report, or Work plan Review - other |
Sent RP response to comments on Vapor Intrusion Summary Report Ridgeline Terrace Apartments. |
Jessica Hall |
| 2/15/2022 |
Update or Other Action |
ADEC received the "Final Vapor Intrusion Summary Report", dated February 2022 from Geosyntec Consultants, Inc. |
Jessica Hall |
| 3/2/2022 |
Site Characterization Report Approved |
ADEC received and approved the Final Vapor Intrusion Summary Report, dated February 2022. |
Jessica Hall |
| 5/3/2022 |
Update or Other Action |
ADEC received the 2022 Annual Report for Long-Term Performance Monitoring of Vapor, dated May 3, 2022 from GeoSyntec Consultants, Inc. |
Jessica Hall |
| 8/2/2022 |
Meeting or Teleconference Held |
ADEC had a phone call with GeoSyntec Consultants, Inc. to discuss concerns about the vapor intrusion management system alarms. It was determined they were a result of building drainage issues during rainfall or snow melt events. Maintenance staff will check the systems daily and drain as necessary and document report findings in the next sampling report. |
Jessica Hall |
| 8/4/2022 |
Site Characterization Report Approved |
ADEC approved the 2022 Annual Report for Long-Term Performance Monitoring of Vapor, dated May 3, 2022. The next sampling event will take place early 2023. |
Jessica Hall |
| 3/10/2023 |
Document, Report, or Work plan Review - other |
ADEC received the 2023 Annual Report for Long-Term Performance Monitoring of Vapor, dated March 9, 2023 from GeoSyntec Consultants, Inc. Results of the January and February 2023 sampling event indicated all thirteen indoor air results from five apartments (units 106A, 146A, 146B, 138A and 138B) were below ADEC target levels for the contaminants of concern for this site. Two effluent samples were also collected from the vapor intrusion management system (VIMS) from buildings 138 and 146. Elevated TCE was observed in both VIMs, however the concentrations have decreased by over 75% since July 2021 when they were first installed. GeoSyntec recommends continuation of long-term monitoring and for the next sampling event to take place in early 2024. |
Shawn Tisdell |
| 7/27/2023 |
Offsite Soil or Groundwater Disposal Approved |
Approved transport request to take approximately 100 gallons of TCE-contaminated purge water to US Ecology for shipment to Grandview, Idaho for disposal. |
Shawn Tisdell |
| 11/9/2023 |
Site Characterization Report Approved |
2023 Groundwater Monitoring Report reviewed. Nine primary groundwater samples were collected at the Wilhour Trust Property on August 16 and 17, 2023 and analyzed for volatile organic compounds (VOCs). Trichloroethene (TCE) concentrations detected in groundwater samples collected from Wells MW1, MW2 and MW7B exceed cleanup levels. The remaining detected concentrations were below the ADEC cleanup levels.
Ponded surface water covered Wells MW6 and MW6B on August 16, 2023, when the well monitoring activities were initiated. The protective monument lid and well plug for MW6B were found to be missing. Both were replaced the next day. Surface water had entered well MW6B so that well was also sampled for gasoline range organics (GRO), diesel range organics (DRO), residual range organics (RRO), and polynuclear aromatic hydrocarbons (PAHs). RRO and 2-methylnaphthalene were detected in Well MW6B at concentrations less than the ADEC Table C cleanup levels. |
Shawn Tisdell |
| 2/6/2024 |
Exposure Tracking Model Ranking |
A new updated ranking with ETM has been completed for source area 75117 auto-generated pm edit BFT - Wilhour Trust Property. |
Shawn Tisdell |
| 3/20/2024 |
Site Characterization Report Approved |
DEC staff reviewed and approved the February 21, 2024 Annual Report for Long-Term Performance Monitoring of Vapor Intrusion Mitigation. Report recommendations indicate that performance monitoring for the past three years of sampling support the effectiveness of the current mitigation systems. The consultant recommends continued monitoring of the vapor intrusion mitigation systems (VIMS) and DEC notification if there are any building structural issues or issues that may indicate abnormal VIMS operation and propose to discontinue verification sampling and annual reporting unless contingency actions again require sampling and annual reporting. |
Shawn Tisdell |
