Copies: Dave Favero, RACER

Transcription

1 MEMO To: Nate Nemani USEPA Region 5 77 West Jackson Boulevard Mail Code: LU-9J Chicago, Illinois Copies: Dave Favero, RACER Arcadis of Michigan, LLC Cabot Drive Suite 500 Novi Michigan Tel Fax From: Christi Kiker Date: Arcadis Project No.: March 28, 2017 B Subject: 1,4-Dioxane Supplemental Investigation Scope of Work RACER Pontiac North Campus Site Pontiac, Michigan On behalf of Revitalizing Auto Communities Environmental Response Trust (RACER), Arcadis of Michigan, LLC (Arcadis) has prepared this Scope of Work to further assess the presence of 1,4-dioxane in groundwater at the Pontiac North Campus Site in Pontiac, Michigan (Site). The supplemental data collected will be used to further refine the Conceptual Site Model in support of evaluating potential exposure pathways and subsequent development and evaluation of corrective measures in the Corrective Measures Study. 1. BACKGROU To help assess the potential strength and transport mechanism for previously identified 1,4-dioxane impacts at the Site, a mass flux investigation was performed in December 2016 in accordance with the Work Plan to Investigate the Presence of 1,4-Dioxane (dated November 16, 2016). As part of this investigation, soil borings were completed near the southern property boundary of the former Fiero property to further characterize the nature and extent of 1,4-dioxane impacts and other volatile organic compounds (VOCs). The borings were completed along a transect using a Geoprobe Hydraulic Profiling Tool (HPT) to map zones of higher permeability within the saturated zone. Based on the HPT results, vertical aquifer profiling (VAP) sampling was performed at each boring location, biased to the more C:\Users\ckiker\Desktop\PNC\1,4-D Work Plan\RACER PNC 14-D Supp Scope of Work_ docx Page: 1/3

2 MEMO permeable zones. In addition, groundwater samples were collected from select existing monitoring wells in the Fiero area and downgradient of Light Non-Aqueous Phase Liquid (LNAPL) Area 1/7 (Area of Interest [AOI] W-10) and within LNAPL Area 10 (AOI W-8) for 1,4-dioxane and VOC analysis. 2. INVESTIGATION RESULTS The results of the mass flux investigation were used to map the hydrostratigraphy and groundwater impacts at high-resolution, to identify preferential flow paths, and to evaluate the strength of associated 1,4-dioxane concentrations migrating off site. Transect and groundwater sampling results are discussed in the presentation included as Attachment 1. At the Fiero downgradient property boundary, 1,4-dioxane was detected at two transect locations at concentrations exceeding 2016 Michigan Department of Environmental Quality (MDEQ) Part 201 drinking water criteria (7.2 micrograms per liter [µg/l]), which was established per emergency order in However, the downgradient area is within a groundwater restriction zone per a City of Pontiac Ordinance, no water supply wells were identified in the downgradient area pursuant to a 2014 well survey, and the maximum detection of 1,4-dioxane (28 µg/l) at transect boring location VAP does not exceed the 2016 MDEQ Part 201 vapor intrusion screening level (29 µg/l). Downgradient of LNAPL Area 1/7 (AOI W-10) and within LNAPL Area 10 (AOI W-8), 1,4-dioxane and other VOCs were not detected. 3. PROPOSED SCOPE OF WORK Based on the results of the mass flux investigation, the following scope of work is proposed to further assess the extent of 1,4-dioxane impacts at the Site: Fiero Downgradient Property Boundary Install one monitoring well with a five-foot screen near VAP and locate the top of the screen at or just below the water table Sample the new well and three adjacent existing wells (MWF1R, MWF12-01, and MWF12-02) quarterly for one year Sample existing up gradient wells (MWF7-01, MWF7-02, MWF7-03, and MWF16-15) semi-annually for two events Downgradient of LNAPL Area 1/7 and LNAPL Area 10 Install one monitoring well with a five-foot screen west of TW-MD-01 and locate the top of the screen at or just below the water table Sample the new well and two adjacent existing wells (MWW1-06 and MWW1-15) quarterly for one year Sample existing up gradient wells (MWW10-SEN02 and MWW10-SEN03) semi-annually for two events The investigation locations are illustrated in Figure 1. The results will be summarized in a memorandum that includes analytical summary tables, well construction logs, figures illustrating updates to the mass flux transect results, and proposed follow-up activities, if necessary. arcadis.com C:\Users\ckiker\Desktop\PNC\1,4-D Work Plan\RACER PNC 14-D Supp Scope of Work_ docx Page: 2/3

3 MEMO 4. SCHEDULE Proposed well installation and the initial sampling event are scheduled to be conducted in April An initial summary memorandum including results from the well installation and initial quarterly sampling activities are expected to be completed and submitted to the U.S. Environmental Protection Agency (USEPA) by July Subsequent quarterly monitoring (three events) will occur beginning in July A brief summary of results will be provided within six weeks after completion of each quarterly sampling event. Figures Figure 1 1,4-Dioxane Investigation Locations Attachments Attachment 1 VAP Results Summary Presentation arcadis.com C:\Users\ckiker\Desktop\PNC\1,4-D Work Plan\RACER PNC 14-D Supp Scope of Work_ docx Page: 3/3

4 Service La yercredits:source:esri, Digita lglobe,geoeye,ea rthsta rgeogra phics, CNES/Airbus DS,U SDA,U SGS,AeroGRID, IGN,a nd the GIS U sercommunity Hollywood Ave W BeverlyAve Ba ldwinave EBeverlyAve Price St MWF8-01 () I W TennysonAve M a nsfield Ave CITY :NOV I,M IDIV :ENV DB:TRY PIC: PM : TM : TR: PROJECTNU M BER: COORDINATESY STEM :NAD1983Sta tepla ne M ichiga nsouth FIPS 2113Feet D:\GIS\ProjectFiles\M otorsliquida tioncompa ny\pontia cnorthca mpus\documents\well_ Insta llsa mple_ _ Bsize.mxd PLOTTED:3/27/20175:03:54PM BY :TY a rbrough W KennettRd DresdenAve Pa rkda le Ave NM e rima c St S M e rima c St W M ontca lm St BurtAve Sa intlouisave Hillside Dr M e rima c St CityLine Rd EKennettRd Ba ldwinave Owens St VAP ' (4) ALL OTHER INTERVALS () VAP ' (28) 32-35' (12J) 37-40' () (4) HPT Sa intcla irst MWF1R EM ontca lm St " " " " # # # # HPT MW0S-01 () VAP () VAP () HPT Y oung St MWF16-15 (13) VAP ' (11) 22-25' (5) 27-30' (7) HPT MWF7-01 (29) VAP () VAP MWF12-01 (9.3)!! () VAP () " " " " " # # # # # VAP () M WW10-05 HPT HPT M WW10-03 HPT HPT HPT SB Wing St MW0S-02 () MWF7-02 (540) MWF7-03 () MWF12-02 (3) Portla nd St MW0S-03 () MWW1-04 () MWW10-04 () IWD7R TW-MD-01 ()! M WW1-06 M WW10-SEN01 NSa gina w St M WW10-06 M WW10-01 M WW10-09 M WW10-08 M WW10-07 M WW1-01 M WW1-15 GWD8R TW MWW10-SEN02 (14) TW MWW10-SEN03 (10) M WW10-SEN05 TW (38) TW-MD-03 TW-MD-05 () () TW-M D-02 TW-M D-04 M WW1-03 M WW1-02 TW-M D-06 M W0S-05 MWM2-04 (0.67 J) TW (3) TW-MD-07 () MWW10-SEN04 () TW TW (62) MWW5-01 (10) EM ontca lm St EM ontca lm St Wolfe St LEGE PROPOSED WELL INSTALLATION/SAMPLING LOCATIONS EdisonSt # HY DRAU LICPROFILING TOOL! SOILBORING " V ERTICALAQU IFERPROFILE EXISTING M ONITORING WELL PROPOSEDWELLINSTALLATION LOCATION! PROPOSEDWELLSAM PLELOCATION (62) μ g/l J U SPS DISTRIBU TION CENTER PROPERTY BOU ARY APPROXIM ATERACERTRU STPROPERTY BOU ARY (NOWAK&FRAU S,JU NE2012) 1,4-DIOXANERESU LT(μ g/l) M ICROGRAM S PERLITER NON-DETECT ESTIM ATEDV ALU E SCALEINFEET RACERTRU ST PONTIACNORTHCAM PU S PONTIAC,M ICHIGAN N Glenwood Ave FIGU RE 1

5 RACER PNC 1,4-DIOXANE EVALUATION December 2016

6 Scope of Work Objective: Evaluate potential extent and magnitude of 1,4-dioxane impacts at Former Fiero and Montcalm Street Scope: Sample existing monitoring wells where available Complete VAP transect at Fiero southern property boundary and evaluate potential zones of 1,4-dioxane flux off-site Arcadis 2015

7 Former Fiero Arcadis

8 HPT Response and Calibration Boring (0-7 ) No recovery No Recovery ( ) SA, very fine to fine, little silt, trace granules ( ) SA, fine, trace medium Sand ( ) SA, medium Wet at 18 (20-27 ) SA, very fine to fine (27-28 ) SA, very coarse, and GRANULES, small to large (28-45 ) CLAY, high plasticity, slow dilatancy; trace very fine sand and medium pebbles Clay Clay and Sand ( ) CLAY and SA, very fine to fine; not saturated HPT-06 Arcadis March

9 Arcadis March

10 Fiero Area Results Multiple wells on Fiero property could not be located (CNL) Two areas of 1,4-dioxane above 7.2 µg/l Max detection (28 µg/l) at VAP does not exceed 2013 VI screening level for GW (29 µg/l) Interpreted Extent 1,4-d > 7.2 µg/l Arcadis March

11 Montcalm Street Area Results All results are for 1,4-D. No other VOC detections Arcadis March

12 Discussion 1,4-Dioxane above Drinking Water Criteria at Fiero property boundary Max concentrations below 2016 VI screening levels Area covered by groundwater restriction ordinance Additional delineation required? Montcalm wells non-detect for 1,4-dioxane Additional samples for verification? Arcadis March

13 Recommendations Install one monitoring well near VAP on Fiero Property Sample quarterly along with three nearby existing wells for 4 quarters. Sample four up-gradient wells semi-annually for 2 events. Install one monitoring well in downgradient LNAPL #1/7 area Sample quarterly along with two existing nearby wells for 4 quarters. Sample two up-gradient wells semi-annually for 2 events. Arcadis March

14 VAP Results 28 March

15 East Half of Transect - HPT Results and VAP Intervals East West VAP TCA: 2 11-DCA: 4 VAP DCA: DCA: 4 11-DCA: 2 VAP DRY 111-TCA: DCA: 4 11-DCA: 3 VAP TCA: 62 T: 1 11-DCA: 8 11-DCE: TCA: 89 T: 1 TCE: 2 11-DCA: 3 11-DCE: TCA: DCA: 3 VAP-05 Arcadis ,4-D results = # ug/l Other VOCs Exceeds most conservative criteria (RDW 7.2 ug/l)

16 West Half of Transect - HPT Results and VAP Intervals East West VAP-04 VAP-03 VAP-02 VAP DRY TCA: 2 11-DCA: 2 11-DCA: DRY TCA: DCA: TCA: 13 T: 2 11-DCA: DCE: TCA: 6 PCE: 5 T:1 11-DCA: TCA: DCA: 7 11-DCE: TCA: 14 PCE: 4 11-DCA: 3 11-DCE: 2 12 J DRY DRY 1,4-D results = # ug/l Arcadis 2015 Other VOCs Exceeds most conservative criteria (RDW 7.2 ug/l)