final reports - arra funded closures

UNDERGROUND STORAGE TANK CLOSURE REPORT FOR

550-GALLON DIESEL FUEL TANK (GWA ALUPANG) AT

GUAM WATERWORKS AUTHORITY ALUPANG SEWAGE PUMPING STATION

TAMUNING, GUAM

March 2011

Prepared for:

Guam Environmental Protection Agency 17-3304 Mariner Avenue, Tiyan, Guam 96913 P.O. Box 22439 GMF, Barrigada, Guam 96921

Prepared by:

apec allied pacific environmental consulting ll l

P.O. BOX 5091 AGANA, GUAM 96932 T 671.477.7310/12 | F 671.477.7311 | [email protected]

Guam EPA, UST Closure Report GWA Tamuning, Sewer Pumping Station (Alupang), 550 Gal

March 2011

1.0 EXECUTIVE SUMMARY 1.1 Introduction A 550-gallon fiberglass reinforced plastic (FRP) underground storage tank (UST) was removed from the Guam Waterworks Authority (GWA), Alupang Sewage Pumping Station (ASPS) Tamuning, Guam in July 2010. Confi rmation soil sampli ng wa s conducted on 13 July 2010. Olfa ctory, PID scre ening an d confirmation soil sample analytical results indicate minor petroleum impacts to the soil below the piping of the UST. 1.2 Sequence of UST Closure Activities Notification for Underground Storage Tank Closure has been prepared for the Guam EPA and is included as an enclosure to this report. Th e concrete-slab demolition was conducted on. 13, July 2010. Liquid tank content s were rem oved and disposed of o n 13 , Ju ly 2010. A Certified Indu strial Hyg ienist (CIH) provided Gas-Free Certification on 13, July 201 0. UST si dewall soil excavation wa s conducted on 13 July, 2010. The UST and associated piping was removed from the site and properly disposed or recycled on. Soil sam ples were collected for confirmation analysis on 13 July, 2010. Followin g the direction a nd under the supervision of Guam EPA APEC personnel backfilled the excavation area on 14-16 July 2010. 1.3 Site Investigation Activities Site investigation activities consisted of visual, olfactory and PID fi eld screening and laboratory analytical soil testing for the following analyt es: 1) Extractable Petroleum Hydrocarbons by EPA Method 8015M, 2) Polynuclear Aromatic Hydrocarbons including benzo(a)pyrene by EPA Method 8270SIM and 3) Benzene, Toluene, Ethylbenzene, Xylene by EPA Method 8260. 1.4 Field Screening and Soil Sample Analytical Results Based o n visual, olfa ctory, PID scree ning an d co nfirmation soil analytical result s indi cate either not detected below the repo rting limit or n ot detected below the Regional Screening Levels established for the project. 1.5 Site Conceptual Model The site conceptual model is ba sed upon field ob servations and laboratory analytical testing performed on environmental media collected at the site and the geological and hydrological conditions at the site. Elevations within the pe rimeter fence of the site range from approximately 19ft – 20ft above MSL. The slope within the perimeter fence of the site is 0.03ft per foot (3% slope) and is visibly flat. The elevation at the site of the UST excavation pit is approximately 20ft above MSL. Approximately one-hundred-percent (100%) of the site is covered by impervious surfaces including buildings, concrete footings, and pavement The a reas to the south a nd e ast of th e site are u ndeveloped a nd veg etated with grass and T angen-tangen (Leucaena leucocephala). To th e north of the site is a paved road (Alupang St.). To the west of the site is a parking lot. Storm water from the nearby rooftop of the generator building associated with the subject UST, drains directly onto the p aved ground surface and flows ho rizontally across the pavement and infiltrates into veg etated buffers surrounding the pavement. The fuel lines of the UST were located approximately 24 in ches bgs an d a ppeared to be undamaged. Site tech nicians ob served no re sidual amounts of fuel contained in the separated fuel line. 1.6 Verification of Site Conceptual Model The two fuel lines leading between the UST and the associated diesel-electric generator were structurally intact and had minimal corrosion. The fuel lines contained no observed residual amounts of fuel. The soil in the area of the separated fuel line was n ot n oted to exhibit olfactory or PID test evid ence of TPH contamination. All analytes tested in soils obtained at the site were found to be below regulatory limits, see Section 4.4, Table 3, for applicable U.S. EPA Region IX, Regional Screening Levels, May 2010.

1

apec P.O. BOX 5091, HAGATNA, GUAM 96932 | TEL. 671.477.7310/12/14 | FAX 671.477.7311 | apecguam@ guam.net

Guam EPA, UST Closure Report GWA Tamuning, Sewer Pumping Station (Alupang), 550 Gal

March 2011

1.7 Conclusions and Recommendations Based u pon these findin gs it is evi dent that there are no si gnificant im pacts to soils at the site. No corrective actions are recommended at this time.

2


TITLE: MAP OF GUAM, INDICATING SITE LOCATION

FIGURE: 1apecallied pacific environmental consulting

ALUPANG UST SITE LOCATION

PROJECT: UST CLOSURE REPORT FOR 550-GALLON DIESEL FUEL TANK (GWA ALUPANG)


TITLE: PROJECT SITE VICINITY MAP.

Figure: 2allied pacific environmental consultingapec

APPROXIMATE SCALE

MILES0 0.5 1

ALUPANG UST SITE LOCATION

1999 USGS


TITLE: SITE PLAN INDICATING SAMPLE LOCATIONS AND ANALYTICAL RESULTS

Figure: 3allied pacific environmental consultingapec

APPROXIMATE SCALE

FEET0 12.5 25

ALUPANG STREET

VEGETATIONBUILDING

CONCRETE SLAB

CRANE

UNPAVED GROUND

EXCAVATED AREA

SOIL STOCKPILE

SAMPLE ALU071310001DISCRETE, DEPTH, 8’

bgs

SAMPLE ALU071310002

DISCRETE, DEPTH 8.5’ bgs

SAMPLE ALU071310003COMPOSITE DEPTH, 26” bgs

ANALYTICAL RESULTS

FENCELINE (PART OF FENCE REMOVED DURING REMOVAL OF UST)

SAMPLE ALU071310001

ALL ANALYTICALS, ND

SAMPLE ALU071310002

TOTAL EFH-10.7 mg/kg

ALL OTHER ANALYTICALS, ND

SAMPLE ALU071310003

TOTAL EFH-22.6 mg/kg

ALL OTHER ANALYTICALS, ND

COMPOSITE SAMPLEGRAB SAMPLE

NORTH


600-GALLON DIESEL FUEL TANK (ASNAMO) AT

GUAM WATERWORKS AUTHORITY AS NAMO SEWAGE TRANSFER STATION

YONA, GUAM

June 2011

Prepared for:


Prepared by:



Guam EPA, UST Closure Report GWA As Namo Sewage Transfer Station, 600G, Yona, Guam

June 2011

1 of 11


1.0 EXECUTIVE SUMMARY Introduction A 600-gallon double walled fiberglass underground storage tank (UST) was removed from the Guam Waterworks Authority (GWA), As Namo Sewage Transfer Station (ANSPS), Yona, Guam in August 2010. Confirmation soil sampling was conducted on 11 August 2010. Olfactory, PID screening and confirmation soil sample analytical results do not indicate petroleum impacts to the soil below the UST cavity or associated piping. No significant impacts to groundwater were revealed as a result of field investigation. Sequence of UST Closure Activities Notification for Underground Storage Tank Closure has been prepared for the Guam EPA and is included as an enclosure to this report. The concrete-slab demolition was conducted on 11 August 2010. Liquid tank contents were removed and disposed of on 12 August 2010. A Certified Industrial Hygienist (CIH) provided Gas-Free Certification on 12 August 2010. UST sidewall soil excavation was conducted on 11 August 2010. The UST and associated piping was removed from the site and properly disposed of on 18 August 2010. Soil samples were collected for confirmation analysis on 11 August 2010. Following the direction and under the supervision of Guam EPA, APEC personnel backfilled the excavation area on 18 August 2010. Site Investigation Activities Site investigation activities consisted of visual, olfactory and PID field screening and laboratory analytical soil testing for the following analytes: 1) Total Extractable Fuel Hydrocarbons (EFH) by EPA Method 8015B, 2) Polynuclear Aromatic Hydrocarbons including benzo(a)pyrene by EPA Method 8270C and 3) Benzene, Toluene, Ethylbenzene, Total Xylenes by EPA Method 8260B. Field Screening and Soil Sample Analytical Results Visual, olfactory, PID screening and confirmation soil analytical results do not indicate concentrations of petroleum hydrocarbons beneath the UST cavity or associated piping. A detectable concentration of diesel range organics (DRO) was detected in the composite sample taken from the soil stockpile. Site Conceptual Model The site conceptual model is based on field observations and laboratory analytical testing performed on environmental media collected at the site and the geological and hydrological conditions at the site. Elevations within the perimeter fence of the site range from approximately 251ft – 257ft above MSL. The slope within the perimeter fence of the site is visibly flat. However, the site was built flat and the ground surface at the site was reinforced using a retaining wall. The original slope of the hillside situated below the site is approximately 0.17ft per foot (17% slope). The elevation at the site of the UST excavation pit is approximately 254ft above MSL. Approximately fifty-percent (50%) of the site is covered by impervious surfaces including buildings, concrete footings, and pavement. The remaining undeveloped areas of the site are vegetated with grass. The undeveloped portions of the property absorb a portion of the stormwater run-off from the site. Storm water drains from the nearby rooftop of the generator building associated with the subject UST through a vertical conduit onto the ground surface near the location of the UST. The two fuel lines leading between the UST and the associated diesel-electric generator were observed to be completely corroded through to the point of disconnection near the openings of entry into the building. The corroded fuel line was located directly below an area where vertical stormwater drainage flowed through a hole in the roof at the location where the UST vent pipe was previously installed. It is likely this corrosion occurred after the tank was no longer being used to store fuel. Site observation PID field testing and soil testing results revealed no significant fuel impacts to the subsurface. Depth to groundwater at the location of the UST excavation is approximately 251 ft below ground surface. No significant drinking water sources exist within 1000 feet of the facility. The prevailing groundwater flow is generally to the northeast towards the Pago River and the Pago Bay. Subsurface porosities in the vicinity of the site are mixed due to the heterogeneous nature of the artificial fill that has been deposited in

Guam EPA, UST Closure Report GWA As Namo Sewage Transfer Station, 600G, Yona, Guam

June 2011

2 of 11


the area. Hydraulic conductivities in the artificial fill materials are estimated to be low to moderate within the vicinity of the site. Verification of Site Conceptual Model The double-walled fiberglass UST was observed to be intact. The UST and piping showed no indication of former leakage. PID field tests and visual and olfactory examination of the soil below the UST and fuel piping revealed no indication of leakage. Laboratory analytical results from the soil sample collected beneath the tank cavity did not indicate the presence of petroleum hydrocarbons above the laboratory’s detection limits. The composite soil stockpile sample contained concentrations of DRO (7.17 mg/kg) and fluorene (0.00727 mg/kg). All other constituents of concern were not detected above laboratory detection limits. Conclusions and Recommendations Non-actionable impacts of fuel related contaminants were evident in the overburden soil removed and sockpiled during UST closure proceedings. No impacts to soil below the UST were discovered. Future release of fuel from this location has been prevented by the removal of the UST and associated piping. Based on a review of the evidence presented within this UST closure report it is recommended that no further action be considered at the site.



ASNAMO UST SITE LOCATION

PROJECT: GUAM EPA, ASNAMO UST CLOSURE

REPORT

N

SUBJECT SITE

SHEET TITLE: TOPOGRAPHIC MAP OF SUBJECT SITE VACINITY

FIGURE: 2allied pacific environmental consulting

apec

PROJECT: GUAM EPA, ASNAMO, UST CLOSURE REPORT

MAP PROVIDED COURTESY OF UNITED STATES GEOLOGICAL SERVICE 2000

SCALE:

0 0.5 1.0

KILOMETERS

N

ASNO-081110-001 (GRAB)DEPTH 10’ BGSANALYTES: ND

FUEL PIPING

DAY TANK

ANALYTICAL RESULTS

PUMP HOUSE/GENERATOR

BUILDING

LEGEND

ASNO-081110-002 (GRAB)DEPTH 5’ BGSANALYTES: ND

ASNO-081110-003 (GRAB)DEPTH 1’ BELOW TOP OF PILEANALYTES: TOTAL EFH DRO: 7.17 mg/kgFLUORENE: 0.007 mg/kg

ASNO-081110-001 (GRAB)

ASNO-081110-003 COMPOSITE

ASNO-081110-002 (GRAB)

DENSE VEGETATION

DENSE VEGETATION

PROJECT: AS NAMO UST CLOSURE REPORT FIGURE: 3allied pacific environmental consulting

apec

0 12.5 25FEET

APPROXIMATE SCALE

UST LOCATION

EXCAVATED AREA

SOIL STOCKPILE

BUILDING

FENCE

DENSE VEGETATION

CONCRETE SLAB

UNPAVED ROAD

N



500-GALLON DIESEL FUEL TANK AT

GUAM WATERWORKS AUTHORITY ASAN SEWER PUMP STATION (GWA CD4)

ASAN, GUAM

June 2011

Prepared for:


Prepared by:



Guam EPA, UST Closure Report GWA Asan Sewer Pump Station, 500 G, Asan, Guam

June 2011

1 of 10

apec P.O. BOX 5091, HAGATNA, GUAM 96932 | TEL. 671.477.7310/12/14 | FAX 671.477.7311 | [email protected]

1.0 EXECUTIVE SUMMARY Introduction This report documents the proceedings of a subsurface site investigation for the closure of an Underground Storage Tank. APEC conducted soil investigation activities at the location of a 500 gallon underground storage tank (UST) at the Guam Waterworks Authority (GWA), Asan Sewer Pump Station, Asan, Guam in August 2010. GWA supervisors indicated that a UST system was never employed at this site. However, initial notification form was on file for a 500-gallon UST located at the Asan site. Confirmation soil sampling was conducted on 23 August 2010. Olfactory, PID screening and confirmation soil sample analytical results indicate low to non-detectable concentrations of petroleum hydrocarbons and VOCs in soil samples collected during this investigation. No potential impacts to groundwater were revealed as a result of field screening or laboratory analytical testing. Sequence of UST Closure Activities Notification for Underground Storage Tank Closure has been prepared for the Guam EPA and is included as an enclosure to this report. The location of the UST was undocumented prior to APEC’s investigation. As a result, APEC conducted underground locator survey using metal detector on 20 August 2010. Based on the findings, the probable location of the UST was determined and soil excavation was conducted on 23 August 2010. Soil samples were collected for confirmation analysis on 23 August 2010. Following the direction and under the supervision of Guam EPA, APEC personnel backfilled the excavation area on 23 August 2010. Site Investigation Activities Site investigation activities consisted of visual, olfactory and PID field screening and laboratory analytical soil testing for the following analytes: 1) Total Extractable Fuel Hydrocarbons (EFH) by EPA Method 8015B, 2) Polynuclear Aromatic Hydrocarbons including benzo(a)pyrene by EPA Method 8270C and 3) Benzene, Toluene, Ethylbenzene, Total Xylenes by EPA Method 8260B. Field Screening and Soil Sample Analytical Results Visual, olfactory, PID screening and confirmation soil analytical results do not indicate levels of petroleum hydrocarbon contamination above project clean-up goals. Site Conceptual Model The site conceptual model is based on field observations, geological and hydrological conditions and laboratory analytical testing performed on environmental media collected at the site. Elevations within the perimeter fence of the site range from approximately 7ft – 8ft above MSL. The slope within the perimeter fence of the site is 0.01ft per foot (1% slope) and is visibly flat. The elevation at the site of the UST excavation pit is approximately 4ft above MSL. Approximately fifty-percent (50%) of the site is covered by impervious surfaces including buildings, concrete footings, and pavement. The remaining undeveloped areas of the site are vegetated with grass. The undeveloped portions of the property absorb a portion of the stormwater run-off from the site. Storm water drains from the nearby rooftop of the generator building associated with the subject UST through a vertical conduit onto the grassy surface near the location of the UST. Depth to groundwater at the location of the UST excavation is approximately 7 - 8 ft below ground surface. Groundwater at the site is brackish water as freshwater and seawater are significantly mixed due to tidal influences. No significant drinking water sources exist within 1000 feet of the facility. The prevailing groundwater flow is generally to the north-northwest towards the Philippine Sea. Subsurface porosities in the vicinity of the site are mixed due to the heterogeneous nature of the artificial fill that has been deposited in the area. Hydraulic conductivities in the artificial fill materials are estimated to be low to moderate within the vicinity of the site.

Guam EPA, UST Closure Report GWA Asan Sewer Pump Station, 500 G, Asan, Guam

June 2011

2 of 10

apec P.O. BOX 5091, HAGATNA, GUAM 96932 | TEL. 671.477.7310/12/14 | FAX 671.477.7311 | [email protected]

Verification of Site Conceptual Model The presence of the 500-gallon UST was not verified during this investigation. Excavation activities at the probable location of the UST (based on metal detector survey) showed no indication of a UST system. Diesel Range Organics and BTEX compounds were not detected above laboratory reporting limits in the soil samples collected during this investigation. A soil sample collected from the excavation pit at a depth of 8.0 feet bgs contained detections of Benzo (b) fluoranthene (0.00754 mg/kg) and Pyrene (0.00721 mg/kg). The soil sample collected from the third excavation pit contained a detection of Benzo (b) fluoranthene at a concentration of 0.00721 mg/kg). All analytes tested in soil samples were below project soil screening thresholds. Conclusions and Recommendations Based on these findings it is evident that minor impacts exist in soil below regulatory screening thresholds in the area of the location of former UST and associated piping. Future release of fuel form this location has been prevented by the removal of the piping and its associated UST. Based on a review of the evidence presented within this UST closure report it is recommended that no further action be considered at the site.

ASAN UST SITE LOCATION



PROJECT: ASAN UST CLOSURE REPORT

N

MILES

APPROXIMATE SCALE0 0.25 0.5

ASAN UST SITE LOCATION

N


TITLE: PROJECT STIE VACINITY MAP


apec

2000 USGS

MAIN SPS

BUILDING

GENERATOR

BUILDING

BUILDING

EXCAVATED

AREASASAN082310003

(8 FT BGS)

ASAN082310002

(8 FT BGS)

ANALYTICAL RESULTSBUILDING

ASAN082310001 (GRAB)

DEPTH 8’ BGS

ANALYTES: NOT DETECTED

ABOVE REGULATORY LIMIT


DEPTH 8’ BGS




DEPTH 8’ BGS



UNPAVED

AREA

HEAVY

VEGETATION

N


TITLE: SITE LAYOUT WITH ANALYTICAL DATA

FIGURE:3allied pacific environmental consulting

apec

APPROXIMATE SCALE

0 10 20FEET

250GALLON

AST

BUILDING

ASAN082310001

(8 FT BGS)


350-GALLON DIESEL FUEL TANK (GWA BARRIGADA) AT

GUAM WATERWORKS AUTHORITY BARRIGADA SEWAGE PUMPING STATION

BARRIGADA, GUAM

March 2011

Prepared for:


Prepared by:



Guam EPA, UST Closure Report GWA Barrigada Sewer Pumping Station, 350 G, Barrigada, Guam

March 2011

1 of 10


1.0 EXECUTIVE SUMMARY Introduction APEC conducted soil investigation activities related to a 350 gallon underground storage tank (UST) at the Guam Waterworks Authority (GWA), Barrigada Sewage Pumping Station, Barrigada, Guam in August 2010. Confirmation soil sampling was conducted on 04 August 2010. Olfactory, PID screening and confirmation soil sample analytical results indicate low to non-detectable concentrations of petroleum hydrocarbons in soil samples collected during this investigation. No potential impacts to groundwater were revealed as a result of field screening or laboratory analytical testing. Sequence of UST Closure Activities Notification for Underground Storage Tank Closure has been prepared for the Guam EPA and is included as an enclosure to this report. Location of the UST was undocumented prior to APEC’s investigation. As a result, APEC conducted underground locator survey using a metal detector on 27 July 2010. Based on the findings, the probable location of the UST was determined and asphalt-slab demolition was conducted on 04 August 2010. Soil excavation was conducted on 04 August 2010. Soil samples were collected for confirmation analysis on 04 August 2010. Following the direction and under the supervision of Guam EPA, APEC personnel backfilled the excavation area on 04 and 05 August 2010. Site Investigation Activities Site investigation activities consisted of visual, olfactory and PID field screening and laboratory analytical soil testing for the following analytes: 1) Total Extractable Fuel Hydrocarbons (EFH) by EPA Method 8015B, 2) Polynuclear Aromatic Hydrocarbons including benzo(a)pyrene by EPA Method 8270C and 3) Benzene, Toluene, Ethylbenzene, Total Xylenes by EPA Method 8260B. Field Screening and Soil Sample Analytical Results Visual, olfactory, PID screening and confirmation soil analytical results do not indicate levels of petroleum hydrocarbon contamination above project clean-up goals. Site Conceptual Model The site conceptual model is based on field observations, geological and hydrological conditions and laboratory analytical testing performed on environmental media collected at the site. Elevations within the perimeter fence of the site range from approximately 196ft – 198ft above MSL. The slope within the perimeter fence of the site is 0.01ft per foot (1% slope) and is visibly flat. The elevation at the site of the UST excavation pit is approximately 196ft above MSL. Approximately fifty-percent (50%) of the site is covered by impervious surfaces including buildings, concrete footings, and pavement. The remaining undeveloped areas of the site are vegetated with grass. The undeveloped portions of the property absorb a portion of the stormwater run-off from the site. Storm water drains from the nearby building rooftops of the site through a vertical conduit onto the grass vegetated area near the perimeter of the buildings. There was no evidence of significant releases of fuel product during the site investigation. Depth to groundwater at the location of the UST excavation is approximately 191-193 ft below ground surface. Groundwater located in the vicinity of the site is available for extraction as drinking water. Guam Waterworks Authority drinking water supply well A-15 is located approximately 700 feet to the north-northeast of the site. The prevailing groundwater flow is generally to the west-northwest towards Agana Bay. Limestone porosities in the vicinity of the site are mixed due to the argillaceous nature of subsurface. Hydraulic conductivities in the argillaceous materials are estimated to be moderate within the vicinity of the site. Verification of Site Conceptual Model The presence of the 350-gallon UST was not verified during this investigation. Excavation activities at the probable location of the UST (based on metal detector survey) showed no indication of a UST system. A soil sample collected from the excavation pit at a depth of 3.5 feet bgs contained Diesel Range Organics (DRO) at a concentration of 4.81 mg/kg (ppm). At a depth of 9 feet bgs, soil sample analytical results do

Guam EPA, UST Closure Report GWA Barrigada Sewer Pumping Station, 350 G, Barrigada, Guam

March 2011

2 of 10


not indicate the presence of DRO or any other analyte of concern above the laboratory reporting limit. The composite soil sample from the excavation stockpile contained DRO at a concentration of 9.75 mg/kg. All other analytes tested in soil samples collected during this investigation were found to be below laboratory detection limits. Conclusions and Recommendations Based on these findings it is evident that the soil beneath the excavated area is not heavily impacted by constituents of concern related to a release of petroleum hydrocarbons. Verbal communications from Guam EPA indicates that the UST system was replaced by an above ground storage tank in June 2001. Based on this information, including the findings of low to non-detectable concentrations of petroleum fuel hydrocarbons and VOCs in soil it is anticipated that no further action is necessary at the subject site.

BARRIGADA UST SITE LOCATION



PROJECT: BARRIGADA UST SITE

INVESTIGATION

N

BARRIGADA UST SITE

PROJECT: BARRIGADA UST SITE INVESTIGATION

TITLE: PROJECT SITE VICINITY MAP.

Figure: 2allied pacific environmental consulting

apec

APPROXIMATE SCALE

MILES0 0.5 1

BARRIGADA UST SITE LOCATION

MAP COURTESY OF UNITED STATES GEOLOGICAL SERVICE, 1999

N

PUMP

STATION

AST

OLD GENERATOR

PAD SIX INCHES

TOP SOIL ABOVE

CONCRETE SLAB

SOIL

STOCK

ANALYTICAL RESULTS

BAR080410-003 (COMPOSITE)

DEPTH 1’ BGS

TIME 16:28

ANALYTES:

DRO 9.75 mg/kg

BAR080410-001 (GRAB)

DEPTH 3.5’ BGS

TIME 12:10

ANALYTES:

DRO 4.81 mg/kg

BAR080410-002 (GRAB)

DEPTH 9’ BGS

TIME 14:40

ANALYTES:

ALL, ND

FENCELINE

PROJECT: BARRIGADA UST SITE INVESTIGATION



apec

0 12.5 25

APPROXIMATE SCALE

FEET

GENERATOR

BUILDING

STOCK

PILE

EXCAVATED

AREA

GRAB SAMPLE LOCATIONS

BAR080410-001 (GRAB), DEPTH 3.5’ BGS

BAR080410-002 (GRAB), DEPTH 9’ BGS

COMPOSITE SAMPLES

LOCATIONS

BAR080410-003

(COMPOSITE)

DEPTH 1’ BGS

GATEGATE


GWA MAMAJANO SEWAGE PUMP STATION UST-001(1,200gallon) AND UST-002 (PREVIOUSLY REMOVED)

AT GUAM WATERWORKS AUTHORITY

MAMAJANO SEWAGE PUMPING STATION TAMUNING, GUAM

March 2011

Prepared for:


Prepared by:

apec lallied pacific environmental consulting ll l

P.O. BOX 5091 AGANA, GUAM 96932

T: 671.477.7310/12 | F: 671.477.7311 | [email protected]

Guam EPA, UST Closure Report GWA Mamajano Sewer Pumping Station UST-001 and UST-002 Tamuning, Guam

March 2011

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1.0 EXECUTIVE SUMMARY Introduction A 1,200-gallon steel underground storage tank (UST-001) was removed from the Guam Waterworks Authority (GWA), Mamajano Sewage Pumping Station (MSPS), Tamuning, Guam in July 2010. Additional investigation activities were conducted at the location of former UST-002 located at the eastern section of the property. Confirmation soil sampling was conducted on 8 July 2010. Olfactory, PID screening and confirmation soil sampling analytical results indicate minor petroleum hydrocarbon impacts to the soil below the product piping and the soil immediately underlying the UST cavity. No significant impacts to groundwater were revealed as a result of this investigation. Sequence of UST Closure Activities Notification for Underground Storage Tank Closure has been prepared for the Guam EPA and is included as an enclosure to this report. The concrete-slab demolition was conducted on 7 July 2010. Liquid tank contents were removed and disposed of on 7 July 2010. UST sidewall soil excavation was conducted on 8 July 2010. The UST and associated piping was removed from the site on 8 July 2010 and properly disposed of and recycled on 6 August 2010. Soil samples were collected for confirmation analysis on 8 July 2010. Following the direction and under the supervision of Guam EPA, APEC personnel backfilled the excavation area on 8 July 2010. Site Investigation Activities Site investigation activities consisted of visual, olfactory and PID field screening and laboratory analytical soil testing for the following analytes: 1) Total Extractable Fuel Hydrocarbons (EFH) by EPA Method 8015B, 2) Polynuclear Aromatic Hydrocarbons including benzo(a)pyrene by EPA Method 8270C and 3) Benzene, Toluene, Ethylbenzene, and Total Xylenes by EPA Method 8260B. Field Screening and Soil Sample Analytical Results Visual, olfactory, PID screening and confirmation soil analytical results indicate levels of petroleum contamination above project clean-up goals in samples collected from the bottom of the northwestern end of the tank cavity and below the fuel piping of the UST. Site Conceptual Model The site conceptual model is based on field observations and laboratory analytical testing performed on environmental media collected at the site and the geological and hydrological conditions at the site. Elevations within the perimeter fence of the site range from approximately 79 – 83 feet above mean sea level (MSL). The slope within the perimeter fence of the site is 0.04ft per foot (4% slope) and is visibly flat. The elevation at the site of the UST excavation cavity is approximately 80ft above MSL. Approximately sixty-percent (60%) of the site is covered by impervious surfaces including buildings, concrete footings, and pavement. The remaining areas are vegetated with grass. The undeveloped portions of the property absorb a portion of the stormwater run-off from the site. Storm water from the rooftop of the building (in closest proximity to the UST) is directed through down-pipes to the surrounding pavement and grassy vegetated areas. Depth to groundwater at the location of the UST excavation is approximately 77 ft below ground surface. No significant drinking water sources exist within 1000 feet of the facility. The prevailing groundwater flow is generally to the north-northwest towards the Philippine Sea. Limestone porosities in the vicinity of the site are moderate. Hydraulic conductivities in the artificial fill materials are estimated to be low to moderate within the vicinity of the site. Verification of Site Conceptual Model The fuel line leading between the UST-001 and the associated day tank was corroded and noticeably leaking. APEC field personnel observed liquid leaking from a corroded fitting upon excavating the trenching for the fuel line. The soil in the area of the broken fuel line was observed by environmental technicians who noted olfactory and PID test evidence of contamination. The laboratory analytical results

Guam EPA, UST Closure Report GWA Mamajano Sewer Pumping Station UST-001 and UST-002 Tamuning, Guam

March 2011

2 of 11


for soil obtained from 1.5 ft below the leaking fuel line indicated levels of Total Extractable Fuel Hydrocarbons of 160 mg/kg (ppm). Petroleum hydrocarbons odor was observed by field personnel during UST excavation activities and confirmed by PID readings. Upon removing the tank from the excavation cavity, a leak was observed at the bottom of the tank. A soil sample collected from the northwestern extent of the tank cavity at 8 feet bgs contained EFH concentrations of 190 mg/kg. At the southeastern extent of the tank cavity, laboratory analytical results indicate the presence of EFH at a concentration of 16 mg/kg from the soil sample collected at 8 feet bgs. Additional investigation at the location of a former UST (referenced herein as UST-002) along the eastern section of the subject site was conducted by APEC on 8 July 2010. Soil sample analytical results indicate the presence of EFH at a concentration of 260 mg/kg at a depth of 8.5 feet bgs at this location. All other analytes tested in soils obtained at the site were found to be below regulatory limits. Conclusions and Recommendations Based on these findings it is evident that minor impacts exist in the area of the location of the corroded, leaking fuel pipe fitting and the associated UST-001. Additionally, concentrations of EFH were detected above the regulatory limit in soil samples collected from the excavation of the former UST-002 along the eastern portion of the site. Future release of fuel from the UST-001 location has been prevented by the removal of the fuel line and its associated UST. Future releases of fuel from the UST-002 location are not anticipated as the former UST and fuel lines were previously removed. Based on this evidence, it is recommended that the Guam EPA consider potential remedial actions at the location UST and associated piping, as an option, a 12-month period of monitored natural attenuation complemented by one scheduled round of soil sampling and analysis to verify the reduction of petroleum hydrocarbons at the end of the remediation period.

MAMAJANO UST SITE LOCATION


FIGURE: 1

apecallied pacific environmental consulting

PROJECT: MAMAJANO UST CLOSURE REPORT

N

ONE MILE RADIUS

MAMAJANO UST SITE

TITLE: TOPOGRAPHIC MAP OF SITE VACINITY


apec

UST SITE LOCATION


APPROXIMATE SCALE

0 1000 2000 4000FEET

Map Courtesy of United States Geological Services, 1978

N

ONE MILE RADIUS

EXCAVATED

AREA

BUILDING

BUILDING

MARINE CORPS

DRIVE (NB)

MARINE CORPS

DRIVE (SB)

MEDIAN MAM070870001 (GRAB)

DEPTH 8’ BGS

ANALYTES: N/A

ANALYTICAL DATA

MAM070810004

MAM070870002 (GRAB)

DEPTH 8’ BGS

ANALYTES: Total EFH: 190 mg/Kg

MAM070870003 (GRAB)

DEPTH 1.5’ BGS


MAM070870004 (GRAB)

DEPTH 8.5’ BGS





apec

APPROXIMATE SCALE

0 10 20

FEET

EXCAVATED

AREA

GENERATOR

PARKING LOT

BUILDING

POWER

POLE

CEMENT WALL

(APPROX 2 FT HIGH)

VEGETATED AREA

MAM070810001MAM070810002

MAM070810003

NOTE: ANALYTES REPORTED

HERE ARE ABOVE SCREENING

LEVELS


1,000-GALLON DIESEL FUEL TANK (GWA PAGO BAY) AT

GUAM WATERWORKS AUTHORITY PAGO BAY SEWER PUMP STATION

CHALAN PAGO, GUAM

June 2011

Prepared for:


Prepared by:



Guam EPA, UST Closure Report GWA Pago Sewer Pump Station (Pago), 1,000 Gal

June 2011

1


1.0 EXECUTIVE SUMMARY 1.1 Introduction Investigation activities rela ting to a 1,000-g allon carbon ste el un derground storage tan k (UST) were conducted at the Guam Waterworks Authority (G WA), Pago Bay Sewer Pump Station (PBSPS), Chalan Pago, Gu am in Septem ber 2 010. Th e UST wa s previously re moved a nd t ransported from the site. Historical photographs indicate the UST was removed from the site on 21 Ju ne 2006. Confi rmation soil sampling was conducted on 02 September 2010. Olfactory, PID screening and confirmation soil sample analytical results indicate petroleum hydrocarbon impacts to the soil below the former UST. 1.2 Sequence of UST Closure Activities Notification for Underground Storage Tank Closure has been prepared for the Guam EPA and is included as an enclosure to this report. The ground-surface demolition and soil excavation was conducted at the location of the forme r UST on 02 Sep tember 2 010. Soil and sa mples were collected fo r confirmatio n analysis on 02 September 2010. Fo llowing the direction and under the supervision of Guam EPA, APEC personnel backfilled the excavation area on 02 September 2010. 1.3 Site Investigation Activities Site investigation activities consisted of visual, olfactory and PID fi eld screening and laboratory analytical soil testing for the followi ng analytes: 1) Total Extr actable Fuel Hydrocarbons (EF H) by EPA Method 8015B, 2) Polynuclear Aromatic Hydrocarbons including benzo(a)pyrene by EPA Method 8270C and 3) Benzene, Toluene, Ethylbenzene, and Total Xylenes (BTEX, collectively) by EPA Method 8260B. 1.4 Field Screening and Soil Sample Analytical Results Visual, olfact ory, PID screenin g and confirmation soil analytical result s indi cate level s of petroleum hydrocarbon contamination an order of magnitude above project clean-up goals at the western end of the former UST tank cavity. 1.5 Site Conceptual Model The site conceptual model is ba sed upon field ob servations and laboratory analytical testing performed on environmental media collected at the site and the geological and hydrological conditions at the site. Elevations within the pe rimeter fence of the site range from approximately 14ft – 17ft above MSL. The slope within t he perimeter fence of the site is a pproximately 0.025ft per foot (2. 5% slope) and is visibly flat. The elevation at the site of the UST excavation pit is approximately 15ft above MSL. Approximately fifty five percent (55%) of the site i s covered by impervio us su rfaces in cluding buildings, concrete footings, an d pavement. The re maining undevel oped ar eas of the site a re v egetated with gra ss. Th e undeveloped portions of the property absorb a portion of the stormwater run-off from the site. Depth to groundwater at the location of the US T excavation i s approximate ly 9-11 ft be low g round surface. Gro undwater at the site is b rackish water as freshwater and seawater are sig nificantly mixed due to tidal influen ces. No drin king water sources exist within 10 00 feet of the facility. Th e prevailing groundwater flow is generally to the southeast towards the Pacific Ocean. Subsurface porosities in the vicinity of the site are low to moderate. Hydraulic conductivities in the subsurface materials are estimated to be low to moderate within the vicinity of the site. 1.6 Verification of Site Conceptual Model Field activities conducted during this investigation confirmed prior removal of t he UST. Corroded piping associated with the UST was found by APEC personnel in the overburden soil of the former tank cavity

Guam EPA, UST Closure Report GWA Pago Sewer Pump Station (Pago), 1,000 Gal

June 2011

2


and appeared to be used as backfill by the previous contractor. The soil below the former tank cavity was noted to exhibit olfactory and PID test evidence of TP H contamination. Laboratory analytical results for soil obtained from 8ft bgs beneath the easte rn and western ends of the forme r UST indi cated levels of Total Extract able Fuel Hydrocarbons of 832 mg/kg (ppm) and 79.4 mg/kg, respectively. No other constituents of concern were detected above laboratory detection limits for the samples submitted during this inve stigation. See S ection 4.3, T able 2, fo r a pplicable U.S. EPA Region IX, Regional Screening Levels, May 2010. 1.7 Conclusions and Recommendations Based upon these findings it is evident that diesel-im pacted soil exists beneath the location of the former UST. Potential for future fuel release at this location was previously prevented by the removal of the UST and a ssociated fuel lin es. A potential reme dial a ction at the lo cation of the petrol eum h ydrocarbon impacted soil might in clude, a s an option, a 12-month period of mo nitored natu ral attenuatio n complemented by one scheduled round of soil sampl ing and analysis to verify the reduction of petroleum hydrocarbons at the end of the remediation period.

TITLE: MAP OF GUAM INDICATING PROJECT SITE LOCATION


PAGO BAY UST SITE LOCATION

PROJECT: PAGO BAY UST SITE INVESTIGATION

PROJECT: PAGO BAY UST CLOSURE REPORT

TITLE: PROJECT SITE VICINITY MAP

FIGURE: 2allied pacific environmental consultingapec

APPROXIMATE SCALE

MILES0 0.5 1.0

PAGO BAY UST SITE LOCATION

2000 USGS

PROJECT: PAGO BAY UST CLOSURE REPORT

TITLE: PAGO BAY UST SITE LAYOUT


0 12.5 25APPROXIMATE SCALE

FEET

ANALYTICAL DATA

PUMP HOUSE

GENERATOR BUILDING

EXCAVATED AREA

VEGETATION

ROAD

PAG0090210001 (GRAB)DEPTH 8’ BGSTIME 11:25ANALYTES:EFH: (832 mg/kg)BTEX: NDPAHs: ND

PAG0090210002 (GRAB)DEPTH 8’ BGSTIME 11:55ANALYTES:EFH: (832 mg/kg)BTEX: NDPAHs: ND

PAG0090210001 8’BGS

PAG0090210002 8’BGS

UNPAVED AREA


6,000-GALLON DIESEL FUEL TANK (GWA PASEO) AT

GUAM WATERWORKS AUTHORITY AGANA MAIN SEWAGE PUMPING STATION

HAGATNA, GUAM

January 2010

Prepared for:


Prepared by:



Guam EPA, UST Closure Report GWA Agana Main Sewer Pumping Station (Paseo), 6,000Gal

January 2010

1.0 EXECUTIVE SUMMARY 1.1 Introduction A 6,000-gallon fiberglass reinforced plastic (FRP) underground storage tank (UST) was removed from the Guam Waterworks Authority (GWA), Agana Main Sewage Pumping Station (AMSPS), Hagatna, Guam in June 2010. Confirmation groundwater and soil sampling was conducted on 30 June 2010. Olfactory, PID screening a nd confi rmation soil sampl e analytical results indi cate minor p etroleum imp acts to the soil below the pi ping of the UST. No significant impacts to g roundwater were revealed as a result of fiel d screening or groundwater laboratory analytical testing. 1.2 Sequence of UST Closure Activities Notification for Underground Storage Tank Closure has been prepared for the Guam EPA and is included as an en closure to this re port. The co ncrete-slab demolition wa s conducted on 28 Ju ne 2010. Liquid tank contents were remov ed and disposed of on 2 9 Ju ne 2010. A Certified I ndustrial Hygienist (CIH) provided Gas-Free Certification on 30 June 2010. UST sidewall soil excavation was conducted on 29 and 30 June 2010. The UST and associated piping was removed from the site and properly disposed or recycled on 30 June 2010. Soil and g roundwater samples were collected for confirmation analysis on 30 June 2010. Following the direct ion and under the supervision of Guam EPA, APEC personnel backfilled the excavation area on 1 July 2010. 1.3 Site Investigation Activities Site investigation activities consisted of visual, olfactory and PID fi eld screening and laboratory analytical soil testing for the followi ng analytes: 1) Total Extr actable Fuel Hydrocarbons (EF H) by EPA Method 8015B, 2) Polynuclear Aromatic Hydrocarbons including benzo(a)pyrene by EPA Method 8270C and 3) Benzene, Toluene, Ethylbenzene, Xylene by EPA Method 8260B. 1.4 Field Screening and Soil Sample Analytical Results Visual, olfact ory, PID screenin g and confirmation soil analytical result s indi cate level s of petroleum contamination an order of magnitude above project clean-up goals at the site of the fuel piping associated with the subj ect UST. La boratory analytical results for groundwater samples collected below the site of the former UST indicate levels below regulatory threshold values. 1.5 Site Conceptual Model The site conceptual model is ba sed upon field ob servations and laboratory analytical testing performed on environmental media collected at the site and the geological and hydrological conditions at the site. Elevations within the pe rimeter fence of the site range from approximately 11ft – 12ft above MSL. The slope within the perimeter fence of the site is 0.03ft per foot (3% slope) and is visibly flat. The elevation at the site of the UST excavation pit is approximately 11ft above MSL. Approximately fifty-percent (50%) of the site is covered by imp ervious surfa ces in cluding building s, concrete footi ngs, a nd pav ement. Th e remaining u ndeveloped areas of the si te are veget ated with g rass. The un developed p ortions of the property absorb a portion of the sto rmwater run-off from the site. Storm water d rains f rom the nearby rooftop of th e gene rator building associated with t he su bject UST throug h a vertical conduit onto th e grassy surface within 9 feet of the location of the UST. One of the two fuel lines leading between the UST and the associated diesel powered electric generator was observed to be heavily corroded. The fuel line was observed to be sep arated at the location of he aviest corrosion at approxi mately 2 inch es bgs. The corroded fuel line was located within 24 inches of t he associated building’s vertical stormwater drainage conduit. Site technicians observed residual amounts of fuel contained in the separated fuel line. Depth to groundwater at the location of the UST excavation is approximately 11 ft below ground surface. Groundwater at the site is brackish water as freshwater and seawater is significantly mixed due to tidal influences. No d rinking water sources exist within 1000 feet of the facility. The p revailing groundwater flow is generally to the north-northwest towards the Philippine Sea. Sub surface porosities in the vi cinity of the site are mixed d ue to the hete rogeneous nature of the a rtificial fill that has been deposited in the

1


Guam EPA, UST Closure Report GWA Agana Main Sewer Pumping Station (Paseo), 6,000Gal

January 2010

area. Hydraulic conductivities in the artificial fill materials are estimated to be moderate within the vicinity of the site. 1.6 Verification of Site Conceptual Model One of the two fuel line s leading bet ween the US T and the asso ciated die sel-electric ge nerator was heavily corro ded an d se parated at ap proximately 2 in ches b gs. The broke n fuel line st ill contain ed residual amounts of fuel and was located within 24 inches of the associated buildings vertical stormwater drainage conduit. The soil in the area of the separated fuel line was noted to exhibit olfactory and PID test evidence of TPH contami nation. The laboratory a nalytical results for soil obt ained f rom 4ft below th e heavily corroded fuel line indicated levels of Total Extractable Fuel Hydrocarbons of 373 mg/kg (ppm). The la boratory analytical results fo r groundwater o btained from 11ft bg s and do wn gradi ent from the corroded fuel line indicated levels of Total Extractable Fuel Hydrocarbons of 0.83 mg/kg (ppm). All other analytes tested in groundwater and soils obtained at the site were found to be below regulatory limits, see Section 4.4, Table 3, for applicable U.S. EPA Region IX, Regional Screening Levels, May 2010. 1.7 Conclusions and Recommendations Based u pon these findin gs it is eviden t that a sma ll quantity (ap proximately 2 cubi c yard s) of diesel-impacted soil exists in the immediate a rea of the lo cation of the corrod ed a nd sep arated fuel line. In addition, the re are n o si gnificant imp acts to g roundwater at the site. Future release of fuel from this location has been prevented by the removal of the remaining fuel, the fuel line and its associated UST. A potential remedial action at the location of the corroded and separated fuel line might include a 12-month period of mo nitored natural attenuatio n com plemented by one scheduled round of soil sampling and analysis to verify the reduction of petroleum hydrocarbons at the end of the remediation period.

2


SHEET TITLE: MAP OF GUAM INDICATING SITE LOCATION

FIGURE: 1

N

Red arrow indicates location of project site

allied pacific environmental consultingapec

PROJECT: GEPA, GWA, AMSPS, (PASEO) UST CLOSURE REPORT

SHEET TITLE: PROJECT VICINITY


MARINE CORPS DRIVE (ROUTE 1)PASEO DE SUSANA PARK

PROJECT SITE

1-MAP-INCH = 1600 FEET

N

PROJECT: GUAM EPA, GUAM WATERWORKS AUTHORITY, AGANA MAIN SEWAGE TRASFER PUMP STATION, (PASEO) UST CLOSURE REPORT

SHEET TITLE: SITE DETAIL DIAGRAM


GEN

ERA

TOR

HO

USE

TANK BED EXCAVATION

N

OVERBURDEN SOIL PILE

PIPE RUN EXCAVATION

mg/kg (soil)RESULTS

0.130PYRENE

0.220PHENANTHRENE

0.130FLUORANTHENE

0.014TOTAL XYLENES

0.0033TOLUENE

373TOTAL EXTRACTABLE FUEL HYDROCARBONS

PASEO-063010-002SAMPLE ID

ND (<0.48 ug/l)TOTAL POLYNUCLEAR AROMATIC HYDROCARBONS

0.83TOTAL EXTRACTABLE FUEL HYDROCARBONS

PASEO-063010-001SAMPLE ID

mg/l (groundwater)RESULTS

ANALYTES DETECTED (Note: Analytes above regulatory limits in bold red)

PERIMETER FENCELINE

CONCRETE TANK VAULT

1-MAP-INCH = 9 FEET

LEGEND

LOCATION OF FUEL PIPE

SAMPLE I.D. AND LOCATION002

ROOF STORMWATER DRAINAGE PIPE

TANK FILL PIPE

LOCATION OF TANK VENT PIPE

001 002

100 FT TO AGANA BOAT BASIN (MARINA)

PROJECT: GUAM EPA, GUAM WATERWORKS AUTHORITY, AGANA MAIN SEWAGE TRASFER PUMP STATION, (PASEO) UST CLOSURE REPORT

PID Test at location -001: 0.0 ppm

PID Test at location -002: 10.7 ppm


350-GALLON DIESEL FUEL TANK AT

GUAM WATERWORKS AUTHORITY PITI (CD-3) SEWER PUMP STATION

PITI, GUAM

June 2011

Prepared for:


Prepared by:



Guam EPA, UST Closure Report GWA Piti Sewer Pump Station (CD-3), 350 G, Piti, Guam

June 2011

1 of 10


1.0 EXECUTIVE SUMMARY 1.1 Introduction APEC conducted soil investigation activities related to 350 gallon underground storage tank (UST) at the Guam Waterworks Authority (GWA), Piti Sewer Pump Station (CD-3), Piti, Guam in August 2010. Confirmation soil and groundwater sampling was conducted on 25 August 2010. Potential impacts to groundwater were revealed as a result of water sample laboratory analytical testing. 1.2 Sequence of UST Closure Activities Notification for Underground Storage Tank Closure has been prepared for the Guam EPA and is included as an enclosure to this report. Location of the UST was undocumented prior to APEC’s investigation. As a result, APEC conducted underground locator survey using metal detector on 20 August 2010. Based on the findings, the probable location of the UST was determined and soil excavation was conducted on 25 August 2010. Soil samples were collected for confirmation analysis on 25 August 2010. Following the direction and under the supervision of Guam EPA, APEC personnel backfilled the excavation area on 25 August 2010. 1.3 Site Investigation Activities Site investigation activities consisted of visual, olfactory and PID field screening and laboratory analytical soil testing for the following analytes: 1) Total Extractable Fuel Hydrocarbons (EFH) by EPA Method 8015B, 2) Polynuclear Aromatic Hydrocarbons including benzo(a)pyrene by EPA Method 8270C and 3) Benzene, Toluene, Ethylbenzene, Total Xylenes by EPA Method 8260B. 1.4 Field Screening and Soil and Water Sample Analytical Results Visual, olfactory, PID screening and confirmation soil analytical results do not indicate levels of petroleum hydrocarbon contamination above project clean-up goals in soil. Confirmation water sample analytical results indicated 817 ug/L total petroleum hydrocarbons as diesel range organics. This value is above the regulatory screening threshold of 50 ug/L. Detections of several PAHs in the groundwater sample were also above regulatory thresholds. Refer to Tables 1 and 2 for tabulated results from soil and groundwater sampling. 1.5 Site Conceptual Model The site conceptual model is based on field observations, geological and hydrological conditions and laboratory analytical testing performed on environmental media collected at the site. Elevations within the perimeter fence of the site range from approximately 5ft – 8ft above MSL. The slope within the perimeter fence of the site is 0.03ft per foot (3% slope) and is visibly flat. The elevation at the site of the UST excavation pit is approximately 8ft above MSL. Approximately sixty five-percent (65%) of the site is covered by impervious surfaces including buildings, concrete footings, and pavement. The remaining undeveloped areas of the site are vegetated with grass. The undeveloped portions of the property absorb a portion of the stormwater run-off from the site. Storm water drains from the nearby rooftop of the generator building associated with the subject UST through a vertical conduit onto the grassy surface near the location of the UST. Depth to groundwater at the location of the UST excavation is approximately 8ft below ground surface. Groundwater at the site is brackish water as freshwater and seawater is significantly mixed due to tidal influences. No significant drinking water sources exist within 1000 feet of the facility. The prevailing groundwater flow is generally to the north-northwest towards the Philippine Sea located 90 feet north-northwest from the location of the UST excavation pit. Subsurface porosities in the vicinity of the site are mixed due to the heterogeneous nature of the detrital coralliferous limestone, beach deposits and artificial fill that comprises the subsurface at the site. Hydraulic conductivities in these mixed subsurface materials are estimated to be low to moderate within the vicinity of the site.

Guam EPA, UST Closure Report GWA Piti Sewer Pump Station (CD-3), 350 G, Piti, Guam

June 2011

2 of 10


1.6 Verification of Site Conceptual Model The presence of the 350-gallon UST was not verified during this investigation. Excavation activities at the probable location of the UST (based on metal detector survey) showed no indication of a UST system. Diesel Range Organics and BTEX compounds were not detected above laboratory reporting limits in the soil samples collected during this investigation. PAHs were detected at concentrations below regulatory thresholds in the soil samples. Diesel Range Organics were detected at a concentration of 817 µg/L in the groundwater sample collected from the excavation pit. Detections of several PAHs in the groundwater sample were also above regulatory thresholds. 1.7 Conclusions and Recommendations Based on these findings it is evident that minor fuel impacts exist in soil and groundwater at the site. While TPH was detected above the regulatory limit in groundwater, it was not detected above the reporting limit in soil. The presence of TPH in groundwater but not in the associated soil suggests that the source of the TPH contamination may be located outside of the area sampled. Based on this evidence, it is recommended that the Guam EPA consider sampling both soil and groundwater at one down-gradient location and one up-gradient location with respect to the UST excavation pit. An optimized remediation strategy should then be designed based on a determination of the location of the source of the fuel release.

PITI UST SITE LOCATION



PROJECT: PITI UST SITE INVESTIGATION

N

ONE MILE RADIUS

N

PROJECT: PITI UST CLOSURE REPORT

TITLE: PROJECT STIE VACINITY MAP


apec

2000 USGS

MILES

APPROXIMATE SCALE0 0.25 0.5

PIT UST SITE LOCATION

VEGETATION

BUILDING

PITI BAY

ANALYTICAL DATA

GENERATOR

BUILDING

EXCAVATED

AREA

PITI 082510 001(GRAB, SOIL)

DEPTH 5’ BGS



PITI 082510 002(GRAB, SOIL)

DEPTH 7’ BGS



PITI 082510 003(GRAB, WATER)

DEPTH 9’ BGS

ANALYTES:

TOTAL PETROLEUM

HYDROCARBONS 817 ug/L

(ppb) (REGULATORY LIMIT 50

ug/L)

BENZO (A) ANTHRACENE

0.627 ug/L (ppb) (REGULATORY

N

PROJECT: PITI UST CLOSURE REPORT

TITLE: SITE LAYOUT WITH ANALYTICAL DATA


apec

SAMPLE IDDEPTH

BGS

PITI082510 001

PITI082510 002

PITI082510 003

5’

7’

9’

MAIN SPS BUILDING

APPROXIMATE SCALE

FEET0 12.5 25.0


LIMIT 0.029 ug/L)

BENZO (A) PYRENE 0.510 ug/L

(ppb) (REGULATORY LIMIT

0.0029 ug/L)

BENZO (B) FLUORANTHENE


LIMIT 0.029 ug/L)

BENZO (K) FLUORANTHENE


LIMIT 0.29 ug/L)

INDENO (123-CD) PYRENE


LIMIT 0.029 ug/L)


2,000-GALLON DIESEL FUEL TANK (GWA YPAO) AT

GUAM WATERWORKS AUTHORITY YPAO SEWER PUMP STATION

TUMON, GUAM

June 2011

Prepared for:


Prepared by:



Guam EPA, UST Closure Report GWA Ypao Sewer Pump Station (Ypao Village), 2,000G, Tumon, Guam

June 2011

1 of 11


1.0 EXECUTIVE SUMMARY 1.1 Introduction A 2,000-gallon fiberglass reinforced plastic (FRP) underground storage tank (UST) was removed from the Guam Waterworks Authority (GWA), Ypao Sewer Pump Station (YSPS), Tumon, Guam in August 2010. Confirmation soil sampling was conducted on 31 August 2010. Olfactory, PID screening and confirmation soil sample analytical results indicate no significant impacts to the soil underlying the UST and associated fuel piping. 1.2 Sequence of UST Closure Activities Notification for Underground Storage Tank Closure has been prepared for the Guam EPA and is included as an enclosure to thi s report. The concrete-slab demolition was conducted on 31 Au gust 2010. F orty gallons of liquid tank cont ents were removed and d isposed of following tan k cleaning on 1 September 2010. A Certified Industrial Hygienist (CIH) provided Gas-Free Certification on 1 September 2010. UST sidewall soil excavation was conducted on 31 August and 1 September 2010. The UST and associated piping was removed from the site an d pro perly disposed o r recycled o n 2 Septembe r 2 010. Soil a nd groundwater samples were collected for confirmation analysis on 31 August 2010. Following the direction and under the supervision of Guam EPA, APEC personnel backfilled the excavation area on 1 September 2010. 1.3 Site Investigation Activities Site investigation activities consisted of visual, olfactory and PID fi eld screening and laboratory analytical soil testing for the followi ng analytes: 1) Total Extr actable Fuel Hydrocarbons (EF H) by EPA Method 8015B, 2) Polynuclear Aromatic Hydrocarbons including benzo(a)pyrene by EPA Method 8270C and 3) Benzene, Toluene, Ethylbenzene, Xylene by EPA Method 8260B. 1.4 Field Screening and Soil Sample Analytical Results Visual, olfact ory, PID screenin g and confirmation soil analytical result s indi cate level s of petroleum contamination belo w p roject cl ean-up goals at the site of the subject UST, a ssociated pi ping, and soil overburden. 1.5 Site Conceptual Model The site co nceptual model is base d on field obse rvations and laboratory analytical testing p erformed on environmental media collected at the site and the geological and hydrological conditions at the site. Elevations within the pe rimeter fence of the site range from approximately 17ft – 22ft above MSL. The slope within the perimeter fence of the site is 0.05 ft per foot (5% slope) and is graded downward towards the no rtheast. The elevation at th e site of the UST excavatio n pit is app roximately 18ft above MSL. Approximately fifty-perce nt (50% ) of t he site i s covered by im pervious surfaces i ncluding buil dings, concrete footings, and pavement. The remaining undeveloped areas of the site are vegetated with grass. The undeveloped portions of the property absorb a portion of the stormwater run-off from the site. Storm water drains from the nearby rooftop of the generator building associated with the subject UST through a vertical conduit onto the grassy su rface near the location of the UST. The UST and associated fuel lines were intact without visible signs of corrosion or release of fuel. Depth to groundwater at the location of the UST excavation is approximately 18 ft below ground surface. Groundwater at the site i s brackish water as freshwater and seawater are significantly mixed due to tidal influences. No significant drinking water sources exist within 1000 feet of th e facility. The prevailing groundwater flow is generally to the north-northeast towards the Philippine Sea. Subsurface porosities in the vicinity o f the site are mixed d ue to the het erogeneous n ature of th e a rtificial fill th at has be en

Guam EPA, UST Closure Report GWA Ypao Sewer Pump Station (Ypao Village), 2,000G, Tumon, Guam

June 2011

2 of 11


deposited i n the area. Hydraulic conductivities in the a rtificial fil l ma terials are estim ated t o be l ow to moderate within the vicinity of the site. 1.6 Verification of Site Conceptual Model Visual, olfa ctory an d PID field screeni ng of excavat ed soil revea led no impa cts of fuel product in the vicinity of the UST. The laboratory analytical results for soil obtained from 4ft below the fuel line indicated levels of Total Extractabl e Fuel Hydro carbons bel ow the 50 mg /kg (pp m) screeni ng thre shold. Minor detections of PAH’s were also discovered below their respective screening threshold. All other analytes tested in soils obtained at the site were found to be below regulatory limits. 1.7 Conclusions and Recommendations Based on these findings it is evident that minor impacts exist in the area of the location of former UST and associated piping and that no significant impacts to groundwater exist at the site. Future re lease of fuel form thi s lo cation h as be en p revented by the re moval of the pi ping it s a ssociated UST. Based on a review of the evidence presented within this UST closure report it is recommended that no further action be considered at the site.



YPAO UST SITE LOCATION

PROJECT: YPAO UST SITE INVESTIGATION

PROJECT: YPAO UST CLOSURE REPORT

TITLE: PROJECT SITE VICINITY MAP


ONE MILE RADIUS

0 0.25 0.5APPROXIMATE SCALE

MILES

YPAO UST SITE LOCATION

2000 USGS

PROJECT: YPAO UST CLOSURE REPORT



GENERATOR BUILDING

PUMP STATION

PARKING LOT

ROAD

DENSE VEGETATION

DENSE VEGETATION

DENSE VEGETATION

DENSE VEGETATION

TRANSFORMER

SOIL STOCKPILE

EXCAVATED AREA

FUEL PIPING

VENT LINE

FENCELINE

APPROXIMATE SCALE0 12.5 25

FEET

ANALYTICAL RESULTS

IPAO083110001 (GRAB)DEPTH 4’ BGSTIME 09:05ANALYTES: EFH (4.14 mg/kg)

IPAO083110003 (GRAB)DEPTH 10’ BGSTIME 09:05ANALYTES: EFH (13.8 mg/kg)

IPAO083110002 (COMPOSOITE)DEPTH 1’ BGSTIME 09:05ANALYTES: EFH (10.5 mg/kg)

IPAO083110001

IPAO083110003

IPAO083110002

LEGEND

UST LOCATION

final reports - arra funded closures

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