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HomeMy WebLinkAbout21007_Hoke Street_VIWP_20171009Aptus Management, PLLC Environmental Management Solutions Aptus Management, PLLC 109 Amber Court Carrboro, NC 27510 October 9, 2017 Sarah Hardison Young VIA EMAIL: sarah.hardison@ncdenr.gov Brownfields Project Manager NC Division of Waste Management 217 W Jones St. Raleigh, NC 27603-6100 SUBJECT: VAPOR INTRUSION SUB-SLAB SOIL GAS TESTING – WORK PLAN PASSAGE HOME SITE – RALEIGH, NORTH CAROLINA BROWNFIELDS PROJECT NUMBER: 21007-17-092 Dear Ms. Young: Aptus Management, LLC (Aptus) is pleased to provide this revised work plan for vapor intrusion (VI) testing at the Passage Home site located at 500 Hoke Street in Raleigh (see Figure 1 below). This work plan addresses only the vapor intrusion assessment comments for the existing building noted in your additional assessment letter dated June 27, 2017. This update incorporates your September 26, 2017 comments to the original work plan dated August 28, 2017. The objectives are to evaluate potential risks due to vapor intrusion, and to support our redevelopment planning. Figure 1. Site Location Map – Passage Home Site, 500, 506 Hoke Street 1412 Garner Road – Raleigh, NC (Source: Wake County GIS). BACKGROUND INFORMATION Hoke Street PH Redevelopment LLC is pursuing a Brownfields Agreement (No. 21007-17-092). A site location map is provided in Drawing 1. The site is comprised of the following three parcels (see Site Map in Drawing 2): Vapor Intrusion Soil Gas Testing Work Plan October 9, 2017 Passage Home Site - Raleigh, North Carolina Aptus Management, PLLC Page 2  500 Hoke Street (Parcel 1703828886)  506 Hoke Street (Parcel 1703920846)  1412 Garner Road (Parcel 1703920658) Due the past industrial use of the on-site building, including waste handling operations by a company called Nyetech which leased the property in 2003/2004, and known groundwater pollution conditions in the vicinity, you requested that we evaluate potential risks due to vapor intrusion (VI). In your letter dated June 27, 2017, you requested a minimum of four (4) sub-slab soil gas samples within the existing building. The adaptive reuse of the building is our current focus and redevelopment of the remainder of the property will be considered later. Therefore, the proposed VI testing is for only the building, and not the balance of the site. SAMPLING WORK PLAN Aptus proposes to collect four (4) sub-slab soil gas samples within the on-site building as shown in Drawing 3. The sampling locations will follow the suggested approach you outlined in the June 27 letter. The actual locations will be determined in the field based on visual observations, locations of walls, doors, flooring conditions, etc. The work will be conducted in accordance with guidance1. Two of the samples will be collected in the western portion of the building where we believe Nyetech stored waste materials near the outside loading dock as shown in the highlighted area in the figure below. Figure 2. Probable 10-Day Storage Area Locations within Site Building, 500 Hoke Street – Raleigh, NC (Source: 1972 Sanborn Map). 1 “Vapor Intrusion Guidance”, NCDENR, Division of Waste Management, Brownfields Program, April 2014. Vapor Intrusion Soil Gas Testing Work Plan October 9, 2017 Passage Home Site - Raleigh, North Carolina Aptus Management, PLLC Page 3 The third sampling location will be in the northeastern part of the building near the former fuel dispenser pad. Lastly, the fourth sample will be located at the southeast area of the building to provide assessment of the remaining quadrant. Sample Collection  Aptus will collect sub-slab soil gas samples from four (4) locations identified as SS-1 through SS-4.  One location (SS-1) will employ an inline tee to collect a duplicate sample for quality assurance purposes for a total of five (5) soil gas samples/analyses.  A hammer drill will be used to bore 5/8-inch diameter holes through the slab to the soil beneath (approximately 1-foot depth). The hole will be cleaned with a small bristle brush and vacuumed of residual dust with a shop vac. The thickness of the slab and the depth to and nature of fill media under the slab will be noted. Vapor Pins® fitted with silicone sleeves will be secured into each boring using a special tool and rubber hammer.  Each Vapor Pin location will be allowed to equilibrate for at least 20 minutes.  The samples will be collected using ¼-inch rigid Teflon tubing and 400-ml Summa canisters, per the attached H&P Sampling Guide: Collecting Soil Vapor into Summa Canisters (see Attachment 1). Small 1- to 2-inch pieces of 1/4" and 3/8" Tygon tubing will be employed to make connections to various valves and fittings of the sampling trains. Tubing will be connected to the barbed fitting of the Vapor Pins and a 3-way valve and 60- milliliter (mL) syringe to form a sampling train for each sample location. Dedicated tubing, fittings, and syringes will be utilized for each sampling point.  The probe tubing will be connected to the sampling train and a shut-in test will be performed to ensure air tight conditions per the Sampling Guide. Subsequently, once the sampling train is deemed leak-free, the probe tubing will be purged of three dead volumes using a 60-ml syringe and leak checked using helium in accordance with the Soil Vapor Sampling Using Shroud Method of Leak Detection in Attachment 2. Assuming 1.5 feet of ¼-inch tubing (inner diameter of 0.177 inches), three dead volumes equals 22 mL. (Note - up to 60 mLs may be purged to ensure sufficient volume for the helium leak check, described below). The actual purge volume will be calculated to account for the probe tubing length, sample train and the thickness of the slab. Shut in tests and leak checks of the sampling trains and probes will be performed at each sample location.  The helium concentration within the shroud will be measured using a MGD-2002 leak detector (or equivalent monitor). The purged soil gas will be collected into a 0.5-L Tedlar bag. After purging, the Tedlar bag will be removed and the contents monitored for helium levels. A successful leak check is deemed when the purged soil gas contains less than 5% of the initial shroud concentration of helium. If helium concentrations exceed 5% in the purged soil gas, adjustments will be made to achieve leak-free conditions and/or a new Vapor Pin location will be installed and tested.  If no leaks are detected, the canister sampling can begin at each of the sample locations.  Each of soil gas samples will be collected using canisters fitted with 100 – 200 ml/min flow regulators over a period of between two to four minutes.  A post-sampling leak check will be performed using helium. After a successful post- sampling leak check, the probe tubing and Vapor Pins will be removed from each location and the borings will be grouted flush to the slab foundation level with cement.  Laboratory analysis request forms will be prepared and the samples shipped under proper chain of custody for analysis using EPA Compendium Method TO-15 “Determination of Volatile Organic Compounds (VOCs) in Air Collected in Specially- Prepared Canisters and Analyzed by Gas Chromatography/Mass Spectrometry Vapor Intrusion Soil Gas Testing Work Plan October 9, 2017 Passage Home Site - Raleigh, North Carolina Aptus Management, PLLC Page 4 (GC/MS)”. (Note – when conducting a post-sampling leak check, helium analysis by the laboratory is not required.) The lab will be contacted ahead of time to ensure that reporting limits will be below applicable residential screening levels. The chain of custody/sample analysis forms will Include vacuum readings (initial and final) during testing and the lab will report the received vacuum on the form. Sampling will be stopped when a residual vacuum of 3 to 5 inches of mercury (Hg) is reached for each canister (i.e., sampling will be monitored closely to ensure that final vacuum does not reach 0 inches of Hg.) REPORTING Upon receipt of the laboratory results, the concentrations will be compared to the Division of Waste Management’s (DWM’s) residential soil gas screening levels (RSGSLs). A written report will be prepared summarizing our field activities, observations, laboratory results, conclusions and recommendations. The field readings for the shut in test, helium leak check and helium readings, and vacuum readings will be included. The findings and conclusions will be used to develop the recommendations regarding the risk of vapor intrusion. CLOSING If you have questions regarding this submittal or associated documentation, please feel free to contact us at (919) 522-7289 at your convenience. Sincerely, APTUS MANAGEMENT, PLLC John Gallagher, PE Robert D. Hill, PE Engineer of Record Principal Consulting Engineer Attachments Aptus Management, PLLC DRAWINGS SITE SITE PARCEL /PROPERTY BOUNDARYADJACENT PARCEL /PROPERTY BOUNDARIESLEGENDFORMERASHLANDCHEMICALFACILITYAUTO REPAIRSERVICEFACILITYSITE - EXISTING BUILDING(500 HOKE STREET) SS-1SUB-SLAB SOIL GASSAMPLE LOCATIONPARCEL / PROPERTYBOUNDARIESLEGENDPOSSIBLE FUELDISPENSER PADAREASOUTHWEST BUILDINGSAMPLE LOCATION(NEAR FORMER ASHLANDCHEMICAL SITE & POSSIBLE10-DAY STORAGE AREA)4TH SAMPLELOCATION(PLACEMENTPROVIDESCHARACTERIZATIONOF REMAININGSLAB AREA) Aptus Management, PLLC ATTACHMENT 1 H&P SAMPLING GUIDE: COLLECTING SOIL VAPOR INTO SUMMA CANISTERS d'T) Mobile Geochemistry Inc. 2470 Impala Drive, Carlsbad, CA 92010 Field Office in Signal Hill, CA Ph: 800-834-9888 www.handpmg.com Rev3, August 2014 SAMPLING GUIDE A: Collecting Soil Vapor into Summa Canisters Recommended Tools/Supplies > Scissors/Snips to cut tubing > Nitrile Gloves > Ball Point Pen > If using a Liquid Leak Check Compound: > 1,1-Difluoroethane "duster spray" or Isopropyl Alcohol > Cloth Towel(s) > Resealable plastic bag Sample Parts/Supplies Provided (Pic 1) These Items are sent 1 per sample (not including duplicate or back up Summa): > A-400 mL Summa Canister w/ male quick connect {may be substituted with 1 L Summa Canister) > B - Sample Kit (vacuum gauge, female quick connect, 100-200 or 50 mL/min flow restrictor, 1/4" barb) > C - Male Luer with 3/8" Tygon tubing connector > D-3-way valve These Items are sent 1 per project: > E - Consumables Bag (which contains): > D-3-way valves (2) > F - 60 mL plastic syringes (2) > G-1/4" Tygon tubing > H- 3/8" Tygon tubing > I-Cable Ties Picture 1 Mobile Geochemistry Inc. 2470 Impala Drive, Carlsbad, OA 92010 Field Office in Signal Hill, OA Ph: 800-834-9888 www.handpmg.com Rev3, August 2014 Connecting the Sample Train to the Soil Vapor Probe 1. 2. 3. 4. 5. Attach a 3-way valve (D) onto the vapor probe 1-way valve by twisting male luer fitting on 3-way valve into female luer fitting on valve. (See Pic 2) Note: If you ore not connecting to H&P's standard soil vapor probe 1-way valve, you will need to make the proper tubing connections to attach the 3-way valve onto the valve connection on the probe. It is highly recommended that the soil vapor probe be equipped with a termination valve in order to conduct a proper shut-in test which will be discussed later. Attach a separate 3-way valve onto plastic purge syringe and then twist male luer end of 3-way valve Into female luer end on the 3- way valve attached to the vapor probe. (See Pic 3) Attach a male luer fitting with 3/8" Tygon tubing connector (C) to 1/4" barb on inlet port of Sample Kit (B). (See Pic 4) Twist male luer fitting on Sample Kit into side port of 3-way valve attached to the sample probe valve. (See Pic 5) Attach Summa Canister to Sample Kit by using the quick connect fittings. Pull back collar on female quick connect attached to Sample Kit, and insert male quick connect on Summa. (See Pic 6) Pi Picture 2 cture Picture 4 -KCiW-Picture 5 Picture 6 d^T) Mobile Geochemistry Inc. Conducting a Shut-In Test 2470 Impala Drive. Carlsbad, CA 92010 Field Office in Signal Hill. CA Ph: 800-834-9888 www.handpmg.com Rev3, August 2014 1. 2. 3. 4. 5. The 1-way valve on the soil vapor probe should be in the Off position. Turn the 3-way valve attached to the 1-way valve so that It is Off in the direction pointing away from all ports on the valve. {See Pic 7) With the 3-way valve attached to the purge syringe turned so that the side port is closed, pull back on the plunger so that you draw a vacuum on all the fittings through to the Summa Canister. The vacuum gauge should now be reading vacuum pressure. Once the needle on the vacuum gauge reaches a vacuum of greater than 10" Hg, immediately turn the 3- way valve on the syringe so that it is Off towards the probe valves. (See Pic 8) Observe the vacuum gauge for at least 1 minute to determine if there is any vacuum loss. If the needle drops, indicating a leak in the sample train, retlghten all fittings and conduct shut-in test again. Note: The vacuum gauge reads in inches of Mercury. 7.4" Hg is equal to 100" H20. You should maintain a vacuum of at least 100" H20 (or 7 -8" Hg) when conducting the shut-in test. Picture 7 Turn 3-way valve so that it is Off in the direction pointing away from ail ports. Turn valve on the soil vapor probe to the Off position. Picture Apply vacuum until vacuum gauge reaches 10" Hg or more, then turn 3-way valve on syringe Off towards the vapor probe. lliP Mobilen Geochemistry Inc. Applying a Liquid Leak Check Compound 1. Be sure to have on Nitrile gloves. 2. Place towel in resealable plastic bag. 3. Carefully spray or pour liquid leak check compound onto towel in bag. Do not oversaturate towel with compound. Note: liquid leak compounds typically used are 1,1-Difluoroethane (duster spray), or Isopropyl Alcohol. 4. Seal up plastic bag. 5. Just prior to purging and sampling of the probe, gently place one saturated towel at the base of the soil vapor probe where the tubing enters the subsurface. Lay another towel near all of the sample train connections. Do not lay towel directly on fittings. (See Pic 9) 6. Discard Nitrile gloves, as compounds can be quite strong, and put on new pair prior to purging and sampling to prevent any cross contamination. 2470lmpaia Drive, Carlsbad, CA 92010 Field Office in Signal Hill, CA Ph: 800-834-9888 www.handpmg.com Rev3, August 2014 Picture 9 Purging Soil Vapor Probes 1. 2, 3. 4. 5. Determine the proper purge volume to be evacuated from the soil vapor probe (e.g. 3 dead volumes). Turn the 3-way valve connected to the probe valve so that it is Off towards the Sample Kit and Summa Canister. Note: There should still be a vacuum from the 3-way valve to the Summa Canister. This vacuum pressure should remain until Summa is to be sampled. Open the valve on the probe. (See Pic 10) Using the syringe to purge, slowly draw out the vapor by pulling back on the plunger to fill syringe. Then expel the purge air by turning the 3-way valve so it is Off towards the probe, and pushing the plunger In. Repeat this process until the desired purge volume is evacuated from the probe. Note: For larger purge volumes, inquire about H&P's Balkenbox purge pump. To maintain a flow rate of less than 200 ml/min, it should take approximately 20 seconds to pull back the plunger a full 60 mL. Picture 10 Valve Off toward Sample Kit and SummaOpen vapor probe valve Vapor Flow 11.?Mobile Geochemistry Inc. Collecting the Summa Canister Sample 2470 Impala Drive, Carlsbad, CA 92010 Field Office in Signal Hill, CA Ph; 800-834-9888 www.handpmg.com Rev3, August 2014 1. After purging has been completed, turn the 3-way valve attached to the On/Off probe valve so that it is Off towards the purge syringe. (See Pic 11) 2. The needle on the Sample Kit vacuum gauge should drop Indicating that the Sample Kit is filling with sample air from the probe. 3. Open the valve on the Summa Canister. 4. The needle on the Sample Kit will rise back up and show the initial vacuum of the Summa Canister. 5. Record starting time and the starting vacuum of Summa Canister. 6. The needle will slowly drop as the Summa Canister fills with the sample vapor. This should take 3-4 minutes to fill a 400 ml size Summa Canister at a flow rate of 100-200 mL/min. If using a slower flow rate, such as 50 mL/min, it should take 8-10 minutes to fill. 7. Allow the canister to completely fill and the needle to reach 0"Hg. 8. Close valve on Summa Canister and disconnect. Record sample end time and ending vacuum of the Summa Canister. 9. Label the Summa with the appropriate sample information. 10. Record sample on the Chain of Custody. Picture 11 Valve Off toward purge syringe Disconnecting Sample Train 1. Disconnect all fittings. 2. Because all sampling is done prior to the purge syringe and the attached 3-way valve, they may be reused for other samples. 3. All other fittings, adaptors, and valves should not be reused in the collection of other samples. Mobile Geochennistry Inc. 2470 Impala Drive, Carlsbad, OA 92010 Field Office in Signal Hill, CA Ph: 800-834-9888 www.handpmg.com RevS, August 2014 Collection Notes > If water is observed in the sample tubing, stop coilection Immediately. If you suspect that water may have entered the Summa Canister, make a note on the sample label and Chain of Custody. > Twist luer fittings into each other so that all valves and gauges are facing up. This may take some practice. > At the standard flow rate of 100 - 200 mL/mIn, each 400 mL Summa Canister should fill in 3 to 5 minutes depending upon soil permeability. If the Summa is not filled within 5 minutes, make note of the vacuum reading. Allow the Summa to fill for another 5 minutes. If it is not filled after 10 minutes, make a note of the vacuum reading and stop collection. > If using all Summa Canister, the canister should fill In 5 to 8 minutes at a flow rate of 100 - 200 mL/min. > Label samples with a ballpoint pen. DO NOT USE SHARPIE! > After sampling, return Summa Canister and Sample Kit back into same box they were shipped in. Please do not write on shipping boxes. > You do not need to return any of the consumable items (i.e. syringes, valves, tubing). > Keep Summa Canisters out of sun and do not chill. Keep at room temperature. > Wash hands or remove gloves between samples to ensure the leak/tracer compound is not on your fingers when connecting fittings. Aptus Management, PLLC ATTACHMENT 2 H&P SOIL VAPOR SAMPLING USING SHROUD METHOD OF LEAK DETECTION H&P Mobile Geochemistry, Inc. 2470 Impala Drive, Carlsbad, CA 92010 Ph. 760-804-9678 www.handpmg.com Soil Vapor Sampling using Shroud Method of Leak Detection Placing a plastic shroud over a soil vapor sampling probe and introducing a gaseous compound, such as helium, into the shroud can be implemented to ensure the probe seal integrity. It may also be used to assess the potential for leaks in the sample train. A plastic shroud is placed over the soil vapor probe location with the tubing of the probe exiting the shroud through a small hole. The valve on the probe termination is connected to the sampling apparatus that is to be used. Smaller purge volumes may only require a syringe to purge, while larger purge volumes may require a sample pump with flow meter and vacuum gauge. A “shut in” test is performed to check for leaks in all sample fittings and connections not contained within shroud. This is achieved by shutting the valve at the probe termination to the off position, then applying a vacuum to all connections between the valve and the sample container (i.e. syringe or summa canister). An in-line vacuum gauge is used to observe any loss in vacuum over a period of time (i.e. 60 seconds), which would indicate a leak in the system. Helium (or other compound) is released into the shroud and a hand held helium detector is used to monitor and maintain a reasonably steady concentration of approximately 50% helium in the shroud. Once the concentration is reached, the soil vapor probe is purged at the recommended flow rate and any probe vacuum is recorded. A Tedlar bag is then collected from the probe by connecting to the exhaust port of the purge syringe to fill, or by using a Tedlar lung box. The contents of the Tedlar bag are then screened with the Helium detector. If the concentration in the bag is ≤10% of the Helium concentration in the shroud, sampling is continued. If Helium concentration in the Tedlar bag is >10% of the shroud concentration, the sampling is stopped and efforts to improve or replace the probe are made. The soil vapor sample is then collected in the appropriate sample container (i.e. syringe or summa canister). Once the sample is taken, a final reading of the shroud concentration is measured with the meter and recorded.