Converting Membrane Interface Probe Sensor Results Into Volatile Organic Chemical Non Aqueous Phase Liquid Distribution Information

Transcription

1 Converting Membrane Interface Probe Sensor Results Into Volatile Organic Chemical Non Aqueous Phase Liquid Distribution Information Presented by: Roger Lamb, R.G Roger Lamb Consulting

2 Gasoline NAPL in High Resolution Former UST PIT MIP FID Sensor Cross-Section Analysis Ground Water Surface

3 Gasoline NAPL in High Resolution NAPL Body Outlined in Yellow

4 MIHPT Diagram 4

5 Ultra Pure Compressed Gases Depth Detector Electrical Generator (self sufficient) Drill Rods MiHpt Transfer Line 5

6 High Resolution Tools -$54,000 Collected over 9 days Conventional Tools - $245,000 Total 27,818 measurements Total 3,568 measurements Collected over 16 years

7 Webinar Outline Direct Sensing Tool Recommendation Recommended Soil/Ground Water Sampling Approaches Case Studies Weathered Gasoline NAPL Case Study 1 Weathered Gasoline NAPL Case Study 2 TCE Case Study

8 Direct Sensing Tools Recommendation For gasoline, aviation fuel, or chlorinated VOCs hire an vendor expert in deploying the MIHPT system. (The LIF and OIP tools can be unreliable for detection of gasoline and aviation fuel NAPLs) If chlorinated VOCs other than TCE or PCE check with vendor on sensitivity of the MIP system sensors to the chemicals of concern. The HPT sensor in the MIHPT tool are needed to determine clays/silts vs. sands or gravels. Variations in lithology need to be understood to reliably compare soil analytical to MIP sensor data.

9 Recommendation for Soil Sampling Collecting soil sample for chemical concentration vs. MIP data only viable for clays or silts. Soil boring advanced within 1 foot of the MIP sounding. Take extra efforts to ensure the MIP sounding and soil boring are plumb. Pre-determine depth intervals from which soil cores will be collected (no longer than 0.5 feet in length). Use closed-tube soil sampling technique, make sure driller is accurate on sample depth. Log the soil sample lithology, check for evidence of NAPL Collect soil cores are depth intervals of varying MIP sensor response, example - low <100,000 uv, medium 250,000 to 750,000 uv, high > 2,000,000 uv.

10 Recommendation for Soil Sampling Use 5 gram soil sampling containers similar to the Terra Core samplers. Use technique to drill hole in soil core liner as specified in GeoProbe Systems literature. For gasoline impact minimum analysis TPH-GRO.

11 Recommended Soil Sampling Reference Material

12 Recommendations for Groundwater Sampling If VOC impact is in granular deposits then use groundwater samples. Install sampling point within 1 foot of MIP soundings Only screen over vary specific depth intervals to 5 foot lengths. Gauge and check for NAPL. Can coorelate NAPL in well to highest MIP sensor response/most permeable layers based on HPT data.

13 PID 100,000 uv No VOC NAPL High Injection pressure ( 70 to 80 psi) clayey deposits PID 2,000,000 uv Possible VOC NAPL PID 10,000,000 uv Likely VOC NAPL Low Injection pressure ( 10 to 20 psi) sandy deposits

14 Soil sample 3.0 to 3.5 feet Soil sample 5.0 to 5.5 feet Soil sample 7.5 to 8.0 feet Soil sample 9.5 to 10.0 feet Install piezometer - 11 to 16 feet

15 Weathered Gasoline NAPL Case Study 1 Retail Service Station multiple gasoline releases s to 2000s. Project located in alluvial deposits -15 feet of clays with sand lens. Property redeveloped as ice cream store. Remediation has involved removal of USTs and buried piping, over excavation of soil at UST pit, and several events of multi-phase extraction. High Resolution NAPL investigation goal remediation feasibility/costs.

16 High Resolution Investigation Program Advanced 22 MIHPT soundings to refusal approx. 16 feet depth. Adjacent to each MIHPT sounding a soil boring was advanced and two soil samples were collected for benzene and TPH-GRO analysis. Forty-four soil samples collected composited over 2 foot intervals, ie. 6 to 8 feet. One of the goals of the soil samples was to develop a gasoline NAPL isopach map to aid in remediation feasibility.

17 Cross-section location shown on next slide

18 Analytical Results Indicative of Gasoline NAPL TPH-GRO in soil concentrations- > 250 to 500 mg/kg. Benzene in groundwater at concentrations > 1 mg/l

19 Soil Analytical Results for TPH-GRO in mg/kg overlain on MIP PID sensor and HPT injection pressure logs (PID is red and HPT is green) ND ND

20 Comparison of MIP PID to Soil TPH-GRO Of the 44 soil samples collected, 41 were collected at depths where MIP data was also collected, 3 soil samples were collected too deep and could not be used for comparison to MIP data. Of those 41 samples 36 (88%) matched the criteria of either: 1) Average MIP PID > 5,000,000 uv = TPH-GRO > 350 mg/kg 2) Average MIP PID < 5,000,000 uv = TPH GRO < 350 mg/kg

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24 Lessons Learned Mapping of MIP PID data can be done by hand and result in okay maps. Collecting soil data for comparison to MIP worked when the cores where 2 foot long, but this is not always the case The MIP sensor data coupled with the soil samples results in documenting a gasoline NAPL body that is double the size estimated from the groundwater samples alone.

25 Weathered Gasoline NAPL Case Study 2 County Truck Maintenance Shop - gasoline releases s to 2000s. Project located in saprolite derived from metamorphic rock-40 feet of clays, silts with sand lens. Private water well usage within 0.25 miles of the gasoline release. Gasoline NAPL contained EDB. High Resolution NAPL investigation goal remediation feasibility/costs.

26 Mobile Phase LNAPL

27 Residual Phase LNAPL Total BTEX > 10 mg/l

28 Gasoline Plume Mapped by MIP PID Sensor Data

29 Locations and results from, MIP groundwater and soil samples collected near source area

30 SOIL SAMPLE ANALYTICAL RESULTS TPH GRO 7,900 mg/kg TPH GRO 1,200 mg/kg TPH GRO 12,000 mg/kg Soil samples collected from 0.5 foot long cores using 5 gram encore samplers PID value of Gasoline NAPL somewhere between 2,000,000 and 4,000,000 uv

31 Estimated Volume of LNAPL Impacted Soil 7,500 to 10,000 cubic yards PID response indicative of Gasoline LNAPL 2,000,000 to 4,000,000 uv

32 Lessons Learned More time was needed to collect soil samples so that a better correlation could be established. The soil samples should have been analyzed onsite, not an offsite lab.

33 TCE NAPL Case Study Former parts manufacturer disposed of waste TCE in pit behind their factory. Factory was sold and the former owners had to put money in escrow to remediate TCE impacted soil/groundwater. Hydrogeology residuum derived from shale, clayey soils with very thin sand lenses. Depth to groundwater surface around 1 foot. Remediation consisted of excavation of soils below disposal pit.

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35 Green shading edge of expected TCE NAPL Using 1% of max. solubility in water rule 14 mg/l is indicative of TCE NAPL

36 High Resolution Investigation Goals Twenty-eight MIHPT soundings advanced to refusal on shale bedrock at a depth of 15 feet approximately. Indications of TCE were based on the MIP halogen specific detector (XSD). Goal of investigation was to map TCE in 3D to aid in remediation. Piezometers installed at all 28 MIHPT soundings locations and groundwater samples collected. Sixteen Soil Samples collected based on MIP XSD.

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38 Collaborative Analytical Results Groundwater Samples Locations TCE mg/l MP01 2 MP02 66 MP MP MP MP06 18 MP07 26 MP08 17 MP MP MP MP12 35 MP13 5 MP MP MP MP MP MP MP MP MP Soil Sample Locations Depth Ft BGS TCE mg/kg MP MP MP MP MP MP MP MP MP MP MP MP MP MP MP MP

39 TCE concentration in Groundwater exceeds 14 mg/l

40 Excavated Soils TCE - 66 mg/l TCE 180 mg/l TCE 200 mg/l TCE 35 mg/l TCE mg/l Highest XSD = 2,500,000 uv Avg XSD = 999,585 uv

41 Estimated Foot Print of TCE NAPL

42 Estimated TCE NAPL volume based on MIP XSD data is using 2,000,000 uv is 12,000 cu/yds 2,000,000 uv

43 MIP to NAPL Takeways 1. Hire expert MIHPT operators 2. Make sure COC can be detected by MIP Sensors 3. Evaluate the data in real-time 4. Collect discreet collaborative samples 6 inch soil cores, 0.5 to 5 feet well screens 5. Record soil sample lithology 6. Analyze soil or groundwater samples onsite 7. Allow for enough time and budget for detailed data analysis

44 Thank You Contact Details Graphical analysis by Steve Cole Principia Mathematica, Inc. Consulting Geologist Specializing in Guaranteeing Contaminated Land Management Results