600 Stewart Street , 98101 206.728.2674

June 14, 2016

Washington State Department of Ecology 3190 160th Avenue SE Bellevue, Washington 98008

Attention: Heather Vick, Site Manager, Toxics Cleanup Program

Subject: Data Gaps Report and Request for NFA Opinion Letter_FINAL 8th and Thomas JVLLC – VCP # NW2976 777 Thomas Street Seattle, Washington GeoEngineers File No. 20341-001-03

OVERVIEW AND BACKGROUND

GeoEngineers, Inc. (GeoEngineers) is submitting this letter on behalf of 8th and Thomas JVLLC (8&T JVLLC) to the Washington State Department of Ecology (Ecology) in response to Ecology’s letter dated May 13, 2016 regarding the completed cleanup action at the 777 Thomas Street property (the “Property”) performed by 8th and Thomas JV LLC pursuant to VCP Project No. NW2976. The Property is located in the South Lake Union neighborhood of Seattle. The Property is bounded by Thomas Street to the north, 8th Avenue North to the east, private property (a church) to the south and an alley to the west. The location of the Property is shown in Figure 1. The Property consists of four lots, referred to as Lots 1, 2, 3 and 4. Figure 2 shows the locations of the Lots relative to the surrounding features.

The Property and any locations where contamination originating from the Property may have come to be located (the “Site”) was enrolled in Ecology’s Voluntary Cleanup Program (VCP #NW2976) in June 2015 following the cleanup action completed concurrent with redevelopment. The cleanup action consisted of remedial excavation of all contaminated soilduring removal of soil throughout the entire Property to a depth of at least 25 feet below original ground surface, with vertical sidewalls at each of the boundary lines of the Property. A seven story high-rise building with two levels of underground parking (“Mark on 8th”) has since been constructed on the Property. http://www.macfarlanepartners.com/projects/mark-on-8th/

Ecology reviewed the June 2015 VCP application and submittal materials and provided an advisory opinion letter dated May 13, 2016 requesting additional information. For ease of reference, a copy of Ecology’s May 13, 2016 letter is included in Appendix A. This response letter provides the additional information requested, and addresses the data gaps identified by Ecology in their May 13, 2016 letter. All actual and potential releases of contamination at the Site have been adequately characterized and appropriate remedial actions have been completed consistent with MTCA, as demonstrated by the information provided in this letter and attachments. The data confirms that conditions at, on and beneath Washington State Department of Ecology | June 14, 2016 Page 2

the Site no longer pose a threat to human health and the environment, and that a No Further Action (NFA) opinion is warranted. On behalf of 8th & Thomas JV LLC, we request that Ecology review the information provided and issue a No Further Action (NFA) opinion.

ASSESSMENT AND CLEANUP ACTION REPORTS

The following reports previously provided to Ecology summarize the environmental conditions and completed remedy at the Site:

■ “Subsurface Exploration, 8th and Thomas Site, 777 Thomas Street, Seattle, Washington 98109,” dated January 9, 2009. G-logics, 2009. ■ “Phase I Environmental Site Assessment, South Lake Union Office Building, 215 8th Avenue North, Seattle, Washington 98109, Tax Parcel 1991201100,” dated December 17, 2010. The Riley Group, Inc., 2010. ■ “Phase II Subsurface Investigation and Independent Cleanup Report, Former Holly Press Building, 215 8th Avenue North, Seattle Washington,” dated February 25, 2011. The Riley Group, Inc., 2011. ■ “Phase I and Limited Phase II Environmental Site Assessment, 777 Thomas Street, 223 8th Avenue North and 220 8th Avenue North, Seattle, Washington 98109,” dated December 22, 2011.” Geosyntec Consultants, 2011. ■ “Phase I and Limited Phase II Environmental Site Assessment, 215 8th Avenue North, Seattle, Washington 98109,” dated December 4, 2012. Geosyntec Consultants, 2012. ■ “UST Removal and Cleanup Action Report, 8th and Thomas Development, Seattle, Washington,” dated October 31, 2014. GeoEngineers, 2014.

PROJECT DESCRIPTION

Construction began for the Mark on 8th project, a seven-story multifamily residential building with two levels of underground parking, in 2014. Construction activities began with the installation of vertical soldier piles and timber lagging around the entire perimeter of the Property to allow mass excavation of all soil contained within the Property to a depth of approximately 25 to 31 feet below the original ground surface (e.g. street grade, which is PHOTO 1: November 11, 2014. Shoring installed around the perimeter of the property and approximately elevation 78 to 81). the beginning of mass excavation (soil removal). Photo 1 (taken on November 11, 2014) shows the shoring system in place and the beginning of mass excavation (soil removal) activities. During mass excavation activities all fill and native soil were removed from the ground surface to a depth ranging from 25 to 31 feet below ground surface (bgs) across the entire Property. No groundwater was encountered

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during construction excavation down to 31 feet bgs. The depth to groundwater was deeper than the lowest elevation of the excavation. It was not necessary to perform any construction dewatering during mass excavation because no groundwater was present.

At the time construction began, one 675-gallon heating oil UST had already been removed from Lot 4 (The Riley Group, 2010). Remaining environmental conditions of potential concern identified by the Phase I and II ESAs included two additional underground storage tanks (USTs; one on Lot 1 and one on Lot 3), and one hot spot of residual contaminated soil on Lot 4. The USTs were removed, and contaminated soil in the vicinity of the USTs along with the hot spot on Lot 4 were remediated during the mass excavation activities in 2014. The USTs and contaminated soil were excavated and transported off site for permitted disposal. Confirmation soil samples were obtained to confirm the successful removal of all contaminated soil from the Property (GeoEngineers, 2014).

Following the completion of the mass excavation that resulted in the removal of fill and native soil across the entire subject property from ground surface to a maximum depth of 31 feet bgs, the seven-story multifamily residential building with two stories of underground parking was constructed. The completed building is shown in Photo 2.

RESPONSE TO ECOLOGY COMMENTS PHOTO 2: Completed Mark 8 Project.

Ecology listed ten bulleted comments in their May 13, 2016 letter and requested additional information. The ten comments are summarized below. Ecology’s comments are paraphrased in italic, bold font, followed by the requested information to address the data gap inbulleted paragraphs.

Ecology Comments 1, 2 and 3: Historical information indicates the presence of potential sources of volatile organic compounds (VOCs), specifically tetrachloroethylene (PCE), on Lots 1 and 2, which was not investigated.

■ Response: Subsurface explorations were completed on Lots 1 and 2 in 2008 and 2011 by G-Logics and Geosyntec, respectively. Six soil samples obtained from five borings completed on Lot 1 (Figure 3) and three soil samples obtained from two borings on Lot 2 (Figure 3) were submitted for chemical analysis of VOCs. The data are presented in the G-Logics report dated 2009, and the Geosyntec report dated 2011. PCE was not detected in any of the soil samples tested (a total of nine samples).All other VOCs analyzed were not detected in any of the soil samples tested with one exception: 1,2,4-trimethylbenzene (0.067 milligrams per kilogram [mg/kg]) was detected in the soil sample B7-5. A cleanup level for 1,2,4-trimethylbenzene has not been established. In addition, one soil vapor sample was obtained from Lot 1 in 2011 and submitted for chemical analysis of VOCs. Neither PCE nor any other VOCs were detected in the soil vapor sample. Three soil-vapor samples were obtained from Lot 2 in 2011 and submitted for chemical analysis of VOCs. PCE was not detected in each of the soil vapor samples and other VOCs were not detected above screening levels with the exception of trichloroethene (TCE), which was detected at concentrations above the

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screening level in two of the three soil vapor samples obtained on Lot 2. However, TCE was not detected in nearby soil samples and did not exceed criteria in deeper soil vapor samples. A summary of the soil and soil vapor samples obtained and chemical analytical results are presented in Table 1 below. The approximate locations of the historic sources of contamination and the 2008 and 2011 explorations tested for VOCs are shown in Figure 3. The locations of the explorations evaluated for VOCs, as well as the spatial distribution of the borings and the depths of the samples (see cross-section on Figure 3) tested are sufficient to assess for possible VOC releases and their potential impact. As demonstrated by the data, the investigation findings do not show evidence of a VOC release.

TABLE 1 SUMMARY OF PRIOR VOC DATA FOR SOIL AND SOIL VAPOR SAMPLES

Depth of Exploration Sample Exploration Exploration Sample Location on Sample ID (feet below VOCs ID Date Media Property ground surface) G1 10.17.2011 G-1/25-26 Soil 25-26 ND 12.08.2008 B4-4 Soil 4 ND B4 12.08.2008 B4-12 Soil 12 ND B5 12.08.2008 B5-7 Soil 7 ND Lot 1 B6 12.08.2008 B6-2 Soil 2 ND B7 12.08.2008 B7-5 Soil 5 ND1

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Ecology Comment 4: In 2010, a soil sample collected by the Riley Group at 0.5 feet below the ground surface from boring P3 (sample identification P3-0.5) contained diesel-range petroleum hydrocarbons at 33,000 milligrams per kilogram (mg/kg), which is greater than the MTCA Method A cleanup level of 2,000 mg/kg. The P3 boring was located immediately adjacent to a storm drain on Lot 4. The boring location was not included in subsequent remedial excavations. A such, Ecology requested confirmation that the diesel-contaminated soil represented by P3-0.5 was removed.

■ Response: The soil represented by soil sample P3-0.5 was removed during the 2011 remedial excavation conducted by The Riley Group, as described in their report, “Phase II Subsurface Investigation and Independent Cleanup Report, Former Holly Press Building, 215 8th Avenue North, Seattle, Washington,” dated February 25, 2011. Figure 4 (attached) shows the location of P3, the sample P3-0.5, and the approximate extent of the 2011 remedial excavation conducted by The Riley Group. The successful removal of all diesel-contaminated soil at this location was confirmed through a cleanup confirmation soil sample (SU-SD-1.5, Figure 4) obtained at a depth of 1.5 feet bgs beneath the location of the shallower contaminated sample P3-0.5. As stated in the Riley Group report cited above: “The cleanup confirmation sample collected from the vicinity of the storm drain [SU-SD-1.5] exhibited nondetectable levels of diesel-range TPHs and VOCs. No further remedial excavation is required near the storm drain.” It is important to note that two figures in prior reports from 2011 and 2014 erroneously show an incorrect location for Boring P3. Specifically, the 2011 Geosyntec Phase I and II Limited Phase II ESA (Geosyntec, 2011) erroneously mapped the P3 location compared to in the confirmed data presented in the Riley Group report. This erroneous mapping of P3 was inadvertently carried through into Figure 2 of GeoEngineers 2014 UST Removal and Cleanup Action Report (GeoEngineers, 2014). The correct location of P3 and samples P3-0.5 and SU-SD-1.5 are provided in Figure 4 attached to this letter.

Ecology Comment 5: In 2010 and 2011 a UST removal and subsequent remedial excavation was conducted by The Riley Group to remove a 675-gallon heating oil UST and diesel-range petroleum contaminated soil in the vicinity of this UST. During the UST removal, a characterization sample (B-11) was obtained at the base of the UST excavation at a reported depth of 11 feet below the ground surface. Following the remedial excavation, two confirmation soil samples obtained at the base of the remedial excavation (SU-WB-10 and SU-EB-10) were obtained at depths of 10 feet below the ground surface. The reported depth of the characterization sample (11 feet bgs) relative to the reported depth of the two base confirmation soil samples (10 feet bgs) would suggest that soil containing diesel-range petroleum hydrocarbons above the MTCA Method A cleanup level was left in place at the base of the remedial excavation.

■ Response: Follow-up research and communication has confirmed that the Riley Group followed proper sequencing and protocols for assessing a release to soil, remediating the release, and confirming the successfully remedial activity. Remedial excavation to remove impacted or contaminated soil at a certain depth would result in the depth of a confirmation sample being lower than the depth of the characterization sample. Based on our research and review of the reported information, the depth of the characterization sample B-11 was most likely reported incorrectly.

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From our experience on commercial properties where a heating oil UST is present, heating oil USTs are typically buried approximately 3 feet below the ground surface. A 675-gallon UST is approximately 4 feet in diameter. Immediately following removal of the 675-gallon UST, the excavation depth was likely at around 7 to 8 feet below the ground surface. Sample B-11 was obtained immediately following the UST removal and prior to any excavation of additional soil from beneath the UST. As such, the reported depth of 11 feet for the B-11 characterization sample is assumed to be incorrect.

Ecology Comment 6: Geosyntec completed subsurface explorations in 2012 on Lot 4. During the exploration program, total chromium was detected in soil samples obtained from borings SB-2 and SB-3 at concentrations of 86.8 and 134 mg/kg, respectively. The concentrations are greater than the MTCA Method A Cleanup Level of 19 mg/kg for Chromium VI and significantly less than the MTCA Method A cleanup level of 2000 mg/kg for Chromium III. Speciation of chromium in soil is necessary to rule out the presence of Chromium VI at the Site.

■ Response: Speciation of chromium at the subject property is not necessary or warranted for the following reasons: . As described in The Riley Group Phase I ESA (The Riley Group, 2010) and the Geosyntec Phase I ESA (Geosyntec Consultants, 2011), Lots 1 through 4 were originally developed as private residences. In the early- to mid-1900s the land use at each of the lots transitioned to commercial. Commercial uses included auto repair, appliance servicing, parking areas, printing and other various commercial businesses. Chromium VI was not identified as a contaminant of potential concern1 based on the historical site uses identified in both of the Phase I ESAs. Therefore, chromium speciation was not necessary and it is appropriate to compare the analytical results to the cleanup level of 2,000 mg/kg for chromium III. The detected concentrations of chromium in the soil samples obtained from borings SB-2 and SB-3 are well below than the MTCA method A cleanup level for Chromium III. . Chromium III is a naturally occurring metal and is relatively common throughout the Puget Sound region. Although the published natural background concentration of Chromium III (Ecology, 1994) is 48 mg/kg, it is not uncommon in Puget Sound for Chromium III concentrations to be higher. The presence of chromium at a commercial site in downtown Seattle is much more likely to be Chromium III than it would be to find Chromium VI. It is not possible to resample soil at this location because all of the soil on the Property has been fully excavated and removed during redevelopment. Soil samples at SB-2 and SB-3 were obtained from near the ground surface at depths of approximately 0.5 to 1.0 feet bgs (Geosyntec, 2012). Soil at the ground surface and below these two soil samples to approximately 30 feet below ground surface was removed during the course of mass excavation.

1 “Hexavalent chromium (Cr(VI)) is a toxic form of the element chromium. Hexavalent chromium is rarely found in nature and is generally man-made. Cr(VI) is widely used in pigments, metal finishing (electroplating), wood preservatives and fungicides, and in chemical synthesis as an ingredient and catalyst.” Source: https://www.osha.gov/Publications/OSHA-3373-hexavalent-chromium.pdf

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Ecology Comment 7: The X-ray department of General Electric Company occupied a commercial building on Lot 4 from 1955 until the mid-1970s. It is possible that radioactive materials were released to the subsurface during this time period and the potential for this type of contamination needs to be assessed.

■ Response: City Directories dated from approximately 1950 to 1970, included in the Phase I ESA (Geosyntec, 2011), show “General Electric Co x ray dept” at a relevant address. GeoEngineers was unable to locate any additional information related to the former “x-ray department.” However, it is extremely unlikely that a release of radioactive materials occurred on the subject property for the following reasons: . Sanborn maps for 1950 and 1969 do not list any flammable or dangerous substances present on the Property. . All of the site historical documents and reports located and reviewed do not reference any evidence or suspicion of a historic release of radioactive materials on or beneath the Property, or in the general area of the Property. . There is no documentation to suggest that a release of radioactive materials occurred. However, in the unlikely event that such a release had occurred, the building structure would have contained the radioactive particles. . If radioactive containers were utilized by General Electric during this time period, and if any radioactive containers were disposed on site, those containers would have been encountered during mass excavation of soil associated with redevelopment. No containers were encountered at the property. In summary, no assessment for radioactive materials is warranted at the site because there is not factual or technical basis to suspect that radioactive materials could have been released to the subsurface.

Ecology Comment 8: Based on the recommendation of additional site characterization activities, groundwater assessment should be considered.

■ Response: As discussed in each of the responses to Ecology comments included above, additional site characterization is not necessary. As such, groundwater assessment is also not necessary at the subject property because: . All historical sources of contamination (USTs) and contaminated soil were successfully removed from the Property. . The contamination at the Property (which has now been remediated) resulted from heating oil and heavy oil-range petroleum hydrocarbons which have no or low mobility in soil media. . According to the chemical analytical results, petroleum hydrocarbons were not detected in any of the confirmation soil samples obtained from the limits of each remedial excavation area at former UST 1 and UST 2, and at all Hot Spot locations. . Subsurface soil encountered in the borings ranged from dense silt, sand, and gravel mixtures to hard silts, sandy silt, and clay, typical of a glacial depositional environment.

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. Groundwater was not encountered in borings completed to approximate depths of 35 feet below original ground surface during previous investigations performed between 2003 and 2012. . Groundwater was not encountered during remedial excavation (depth ranging from 20 to 26 feet bgs) at former UST 1, UST 2, and Hot Spot locations and construction excavation (depth ranging from 30 to 32 feet bgs) in 2014. . GeoEngineers reviewed historical groundwater data available from United States Geological Survey (USGS) National Water Information System – Mapper. According to the USGS, the depth-to-groundwater at a former monitoring well (USGS Station 473710122200601 25N/04E-30R01) located in the vicinity and downgradient from the Property (shown on Figure 5) was measured at approximately 78 feet bgs.Based on the previous investigation reports, field observations during remedial and mass excavation activities, and historical USGS data, regional groundwater is deeper than 50 feet bgs, and could be as deep as 78 feet bgs at the Property.

Ecology Comment 9: Chemical analytical data for the last decade must be submitted to Ecology’s Environmental Information Management (EIM) database.

■ Response: All data generated by GeoEngineers during the course of remedial activities have been uploaded and accepted into EIM. Additionally, we have also uploaded the 2011 and 2012 data obtained by Geosyntec. Based on our conversation with Ecology (Heather Vick) on June 7, 2016, we will not be required to upload the data obtained by The Riley Group and G-Logics during their site exploration activities.

Ecology Comment 10: Please consider using Ecology’s Remedial Investigation (RI) checklist for future submittals.

■ Response: The subject property was enrolled in Ecology’s Voluntary Cleanup Program in June 2015, and the RI checklist (published in May 2016) was not available at that time. We will use the RI checklist in future submittals.

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We appreciate your timely review of the additional information provided in this letter. We hope that we have answered all of your questions and concerns, such that we may obtain an Unrestricted Site NFA determination for the cleanup actions completed on and beneath the Property. If there are questions regarding this submittal, please contact us.

Sincerely, GeoEngineers, Inc.

Jessica Smith, LG David A. Cook, LG, CPG Senior Project Manager Principal

JAS:DLC:lw

Attachments: Figure 1. Vicinity Map Figure 2. Lot Identifications Figure 3. Response to Ecology Comments 1, 2 and 3 Figure 4. Response to Ecology Comment 4 Figure 5. Ecology Comment 8, Location of USGS MW Appendix A. May 13, 2016 Letter from Ecology

cc: John Schwartz, The Schwartz Company Ken Lombard, MacFarlane Partners Britt Wenzler, MacFarlane Partners Ken Lederman, Foster Pepper PLLC

Disclaimer: Any electronic form, facsimile or hard copy of the original document (email, text, table, and/or figure), if provided, and any attachments are only a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record.

File No. 0000-001-00 File No. 20341-001-03 Hayes St W Garfield St 99 E Garfield St BorenBoren ParkPark Garfield St UV W Galer St

1St Ave1St N Galer St 8Th Ave N Ave 8Th

5Th Ave N 5Th

7ThAve W W Lee St Lee St

FederalAve E Observatory Court Queen Anne Greenbelt §5 LakeLake UnionUnion ¨¦ Highland Dr BhyBhy KrackeKracke ParkPark 16ThAve E ParsonsParsons GardensGardens VolunteerVolunteer ParkPark W Prospect St Prospect St KerryKerry ParkParkHighland Place Fairview Ave N Ward St LakeviewLakeview PlacePlace W Kinnear Pl Prospect St E Prospect St

Aloha St Ward Springs ParkAve6Th N E Ward St

1StAve W E Aloha St Valley St Kinnear Park 8ThAve N W Roy St Bellevue Place Bellevue Place VolunteerVolunteerE Valley Parkway ParkwaySt

Roy St BoylstonAve E Elliott Ave W 2NdAve W

3Rd Ave3Rd N 4ThAve N MinorAve N Roy St E Roy St E Roy St 3Rd Ave3Rd W Mercer St Mercer St

Terry Ave N Terry

9ThAve N

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Republican St Republican St 12ThAve E 4ThAve W TashkentE Republican Park St DexterAve N Tashkent Park

W Harrison St 14ThAve E

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17ThAve E Harrison St Harrison St 9Th Yale Ave N Yale

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QueenAnne Ave N E Harrison St W Thomas St Thomas St Elliott Bay Park Thomas St Cascade Playground E Thomas St Elliott Bay Park 4Th Ave N ! Cascade Playground W John St John St ThomasThomas StreetStreet ParkPark

4ThAve N 6ThAve N SITE John St E John St Taylor Ave Taylor N Williams Place Denny Way Denny Park Denny Playfield Yale Ave Ave10Th E Denny PlayfieldMinor Ave E Denny Way Boren Ave 3Rd Ave 6Th Ave 8Th Ave Eagle St Bell St Terry Ave E Howell St Lenora9Th StAve Clay St BobbyBobby MorrisMorris PlayfieldPlayfieldE Olive St

Battery St 7Th Ave

MelroseAve Cedar St BellevueAve E Pine St

Broad St Vine St Ave Summit Map Map Revised:May 14, 2013 EL Regrade Park4Th Ave BelmontAve Wall St Regrade Park E Pike St BorenBoren PikePike PinePine ParkPark BoylstonAve McGilvra Place Olive Way E Union St E Union St

Blanchard St Pine St

Virginia St Hubbell Pl FirstFirst HillHill ParkPark SpringSpring StreetStreet ParkPark 5Th Ave Spring St E Marion St VictorVictorAlaskan SteinbrueckSteinbrueck Way ParkPark Pike St

Freeway Park Ave 11Th

Broadway Spring St Marion St 12ThAve Union St Madison St 7Th Ave E Cherry St FirehouseFirehouse ParkPark University St E James St 13ThAve

Seneca2Nd Ave St Columbia St Waterfront Park Waterfront ParkWestern Ave 1St Ave Cherry St Jefferson St 16ThAve Marion St 17ThAve James St Terrace St

10ThAve

15ThAve Columbia St 14ThAve 18ThAve E Spruce St

E Fir St Harborview Park 16ThAve PioneerPioneer SquareSquare ParkParkCity Hall ParkYesler Way

LangstonLangston HughesHughes CulturalCultural ArtsArts KlondikeKlondike GoldGold RushRush NHPNHP S Main St KobeKobe TerraceTerrace ParkPark PrattPratt ParkPark

S King St S King St S Weller St

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Mason UV16 Feet 167 Pierce UV Notes: Vicinity Map Path: Path: \\red\projects\20\20341001\GIS\203400102_F1_VicinityMap.mxd 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. 8th & Thomas Project Site cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of 777 Thomas this communication. Seattle, Washington 3. It is unlawful to copy or reproduce all or any part thereof, whether for personal use or resale, without permission. Data Sources: ESRI Data & Maps, Street Maps 2005 Figure 1 Transverse Mercator, Zone 10 N North, North American Datum 1983 North arrow oriented to grid north Office:Redmond

P:\20\20341001\03\CAD\Data Gaps Report\2034100103_F02_Lot Identifcations.dwg\TAB:F2 modified by cvanslyke on Jun 09, 2016 - 17:25

LOT 1 LOT

LOT 3 LOT LOT 2 LOT LOT4 Notes 1. The locations of all features shown are approximate. Reference: CAD drawing 20120504_2011105-03_XS-SUR.dwg provided by Bush, Roed & Hitchings dated 4/12. 2. This drawing is for information purposes. It intended to assist in GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. showing features discussed in an attached document. property boundary was excavated to depths of approximately 25 to 31 feet below ground surface. Approximate Property boundary. All soil within the LEGEND: 8th and Thomas Development 30 Lot Identifications Seattle, Washington W FEET N 0 S E Figure 2 30 Legend: Approximate Property boundary

Closed-in-place (concrete/slurry filled) USTs

Exploration performed by other consultants between 2003 and B-1 2011

SV-1 Soil vapor sample location by Geosyntec, 2012

VOCs (including PCE) were not detected in soil and soil vapor samples obtained from these borings with the exception of 1,2,4-trimethylbenzene in B7-5 at concentration of 0.067 mg/kg.

Approximate location of soil and soil vapor sample submitted for VOCs. B-11 PCE was not detected in each of the B-4 samples. B-10 A B-7 G-1 A' All soil within the property boundary G-11 was removed to a maximum depth of SV-1 approximately 25 to 31 feet below the B-6 B-5 original ground surface. Former Boiler Room and Paint Room Former UST 1 Location UST fill port G-2 B-1 VOCs Volatile organic compounds G-10 G-3 G-13 PCE Tetrachloroethylene

UST Underground Storage Tank

B-8 BGS Below Ground Surface G-4 B-3

G-6 FORMER N

W E

S 30 0 30

Approximate Former Boiler and Paint Rooms FEET Alley 8th Ave. N. SV-1 G-1 B-6 A B-7 ⅊ A' Notes B-5 B-4 Elevation 83 1. The locations of all features shown are approximate. Elevation 77 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.

Former UST-1 Reference: CAD drawing 20120504_2011105-03_XS-SUR.dwg provided by Bush, Roed & Hitchings dated 4/12.

Ecology Comments 1, 2 and 3 Characterization of VOCs on Lots 1 and 2 8th and Thomas Development Seattle, Washington

Figure 3 P:\20\20341001\03\CAD\Data Gaps Report\2034100103_F03_Ecology Comments.dwg\TAB:F3 modified by cvanslyke on Jun 09, 2016 - 17:29 P3-0.5

SU-SD-1.5

Approximate Storm Drain Extent of Former UST Remedial Excavation

P1

P2

P4

Legend: Approximate Property boundary

UST removed from the site in December, 2010

Approximate extent of former UST remedial excavation performed in December, 2010

P3.05 Exploration performed by Riley Group in 2010 Ecology Comment 4 Notes Confirmation of Remedial Excavation at SU-SD-1.5 Confirmation Soil Sample obtained by Riley Group in 2011 1. The locations of all features shown are approximate. N 2010 Soil Sample P3-0.5 2. This drawing is for information purposes. It is intended to assist in Diesel-range hydrocarbons detected at a concentration greater than the showing features discussed in an attached document. W E MTCA Method A cleanup level. Soil represented by this sample was 8th and Thomas Development GeoEngineers, Inc. cannot guarantee the accuracy and content of subsequently overexcavated and transported off-site for permitted disposal. electronic files. The master file is stored by GeoEngineers, Inc. and S Seattle, Washington will serve as the official record of this communication. 10 0 10 Contaminants of concern not detected in soil sample. Reference: CAD drawing 20120504_2011105-03_XS-SUR.dwg FEET Figure 4 Underground Storage Tank provided by Bush, Roed & Hitchings dated 4/12. UST P:\20\20341001\03\CAD\Data Gaps Report\2034100103_F04_Ecology Comment.dwg\TAB:F4 modified by cvanslyke on Jun 09, 2016 - 14:31 07/22/2016 Ecology Comment 8, Location of USGS MW

Notes: th 1. The locations of all features shown are approximate. 8 and Thomas Development 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the Seattle, Washington accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. 03 03 Exported: Date and will serve as the official record of this communication. 001 - - Figure 5 Data Source: Aerial obtained from Google Earth dated 2016 20341

APPENDIX A May 13, 2016 Letter from Ecology