2 

May 4, 2010 

Greg Yamasaki, P.E. 

FISC Pearl Harbor, Code 701 

1942 Gaffney Street, Suite 100 

Building 1757, 2nd Floor 

Pearl Harbor, HI 96860-4549 

Subject: Type 1 Letter Report – Re-evaluation of the Tier 3 Risk 

Assessment/Groundwater Model & Proposed Course of Action 

Red Hill Bulk Fuels Storage Facility, Pearl Harbor, HI 

Contract #N47408-04-D-8514, Task Order 54 

INTRODUCTION

This Type 1 Report is required in accordance with the Red Hill Bulk Fuel Storage Facility 

Groundwater Protection Plan (TEC, 2008) as revised in 2009 (the Plan). In October 2008, 

concentrations of petroleum hydrocarbons in groundwater beneath the Red Hill Bulk Fuel 

Storage Facility (the Facility) exceeded levels associated with Category 4 status, as defined by 

the Plan. In accordance with the Plan, Category 4 status requires the United States (US) Navy to 

produce a Type 1 Report that documents the re-evaluation of the Tier 3 risk assessment and 

associated groundwater model (TEC, 2007a). 

This Type 1 Letter Report is prepared for the Naval Fleet Engineering Service Center (NFESC) 

and the Pearl Harbor Naval Base Fleet Industrial Supply Center (FISC) by TEC Inc. (TEC) under 

contract N47408-04-D-8514, Task Order 54. Under Task Order 54, TEC is providing 

environmental compliance services associated with past releases of petroleum hydrocarbons to 

the subsurface bedrock and the underlying groundwater aquifer. 

SITE DESCRIPTION AND BACKGROUND

The Facility includes twenty 12.5 million-gallon (Mgal) underground storage tanks (USTs) 

located within the Red Hill Ridge, Halawa Valley, Hawaii. The Facility also includes a series of 

tunnels and pipelines which deliver fuel to and from Pearl Harbor Naval Base (Figure 1). The 

Facility was constructed prior to World War II to support naval activities in the Pacific. 

Pertinent information regarding the Facility includes: 

 The Facility is exempt from many of the Federal and State UST Program requirements 

because it was field-constructed; 

3 

 The Facility has stored diesel fuel, Navy Special Fuel Oil (NSFO), Navy Distillate (ND), 

Jet Propulsion Fuel 5 and 8 (JP-5 and JP-8), and F-76 (diesel marine fuel), and for a short 

time, aviation gasoline (AVGAS) and automobile gasoline (MOGAS) in selected USTs; 

and 

 The Facility overlies the Waimalu and Moanalua aquifer systems, which are pumped 

extensively for potable water usage by the Honolulu Board of Water Supply (HBWS) and 

the Pearl Harbor Water System (PHWS). 

Previous environmental investigations have determined that petroleum from past releases has 

migrated from the USTs to the underlying groundwater. A groundwater contaminant transport 

model was developed to evaluate the threat to surrounding potable water wells. In addition, a 

risk assessment was conducted to estimate current and future risk, based on the model. Current 

risk was found to be insignificant because petroleum had not migrated into nearby drinking water 

wells (Figure 2). 

The US Navy Well 2254-01 pumps approximately 4.6 million gallons per day (mgd) of water 

from a water tunnel (infiltration gallery) that extends approximately 1,280 feet across the water 

table, southwest of the Facility. The US Navy developed the Plan (TEC, 2008) to mitigate this 

potential future threat. The Plan specifies quarterly groundwater monitoring at a network of 

wells within the Facility as well as site-specific action levels and specific mitigation actions 

when these action levels are observed. 

In October of 2008, results for Total Petroleum Hydrocarbon, Diesel Range Organics (TPHDRO) by United States Environmental Protection Agency (USEPA) Method 8015 from 

groundwater samples collected at RHMW02 were 4,540 g/L in the primary sample and 6,300 

g/L in the duplicate sample for an average TPH-DRO concentration of 5,420 g/L. This 

average concentration exceeded the site-specific action level of 4,500 g/L, which is the 

solubility limit of TPH-DRO. These results triggered a Category 4 response action in 

accordance with the Plan. RHMW02 is located within the Facility lower access tunnel, 

approximately 2,060 feet from the US Navy Well 2254-01 infiltration gallery. 

A Category 4 response is required by the Plan because high concentrations of petroleum 

contamination in groundwater are the risk driver at the Facility. Specifically, the results of the 

groundwater model and risk assessment (TEC, 2007a) indicate that for an imminent risk to 

occur, fuel would be within approximately 1,100 feet of the US Navy Well 2254-01 infiltration 

gallery. 

This Type 1 Report provides the required Category 4 response as follows: 

 Re-evaluate the Tier 3 Risk Assessment (TEC, 2007a); 

 Re-evaluate the groundwater model assumptions and results (TEC, 2007b); and 

 Provide a proposal to Hawaii Department of Health (HDOH) regarding a course 

of action. 

A comprehensive re-evaluation of a risk assessment/groundwater model as required for this Type 

1 Report is a complex task requiring a significant amount of field work and technical analysis. 

The completion of this field work and detailed technical evaluation was necessary before this 

Type 1 report could be issued. 
Figure 2. 

Area Wells and Aquifer SystemsGroundwater Gradient Study Red Hill Bulk Fuel Storage Facility, Pearl Harbor, Hawaii

Waimalu SystemPearl Harbor Aquifer Sector

Moanalua SystemHonolulu Aquifer Sect
5 

In order to reassess the threat to water supply wells in the study area, the US Navy installed an 

additional groundwater monitoring well (RHMW05) between the Facility and the US Navy Well 

2254-01 infiltration gallery, approximately 600 feet from the infiltration gallery. This well is 

now sampled quarterly with results included in the US Navy’s quarterly reports to HDOH. 

In addition, a sensitivity analysis was conducted on the risk assessment to determine the 

assumptions with the greatest potential for adversely impacting the results. The assumptions 

presented below were re-evaluated based on this sensitivity analysis. The site-specific risk-based 

levels (SSRBLs) presented in the Plan were based on the following Tier 3 Risk 

Assessment/groundwater model assumptions: 

1. the concentration of dissolved fuel hydrocarbons in the groundwater as measured by 

USEPA Method 8015 is limited to 4,500 g/L, the computed maximum solubility 

resulting from JP-5 fuel in direct contact with the groundwater surface; 

2. the groundwater flows “mauka to makai”(i.e., mountain to ocean), a direction that places 

the US Navy Well 2254-01 directly down gradient from the USTs; and 

3. the dissolved fuel hydrocarbons will degrade at a rate that was modeled using the reactive 

transport model code RT3D (the modeled bulk degradation rate was about 0.009 per 

day).

RE-EVALUATION EFFORTS IN RESPONSE TO THE CATEGORY 4 STATUS

The Category 4 results from the groundwater samples collected from RHMW02 in October 2008 

during Round 13 by USEPA Method 8015 for TPH-DRO (4,540 g/L; 6,300 g/L in the 

duplicate sample; for an average of 5,420 g/L) exceeded the calculated solubility limit of 4,500 

g/L for JP-5. These results and a Category 4 status given to RHMW02 necessitated a reevaluation of the Facility Tier 3 Risk Assessment and groundwater model. 

Re-evaluation of the Groundwater Flow Direction/Gradient 

A study was undertaken to better understand the groundwater flow direction and gradient in the 

vicinity of the Facility. The SI report (TEC, 2007) reported a groundwater flow direction to the 

south when the pumps at the US Navy Well 2254-01 were off or operating at normal capacity, 

and a groundwater flow direction to the north-northwest when the pumps were operating at their 

maximum capacity. This was much different than the assumed “mauka to makai” flow direction 

of the west-southwest. To get a more accurate estimation of the groundwater flow direction, 

TEC contracted Pacific GPS to do a precision global positioning system (GPS) vertical survey of 

all wells that are not in the lower access tunnel, but were used in the 2006 aquifer test detailed in 

the SI report (TEC, 2007a). 

The re-evaluation of the groundwater flow direction and gradient in the vicinity of the Red Hill 

Facility shows a local flow direction from the USTs toward the US Navy Well 2254-01 as 

expected. The gradient for this flow direction is approximately 0.00022 feet/feet. This 

evaluation also shows a regional component flowing to the northwest. The gradient for this flow 

direction is approximately 0.00028. The letter report detailing the groundwater flow/gradient 

study is included as Attachment A. 

Re-evaluation of the Tier 3 Risk Assessment 

Analytical results from RHMW02 collected during Round 13 (October 2008), placed RHMW02 

in a Category 4 status as defined by the Plan. As discussed earlier, this prompted a re-evaluation 
6 

of the groundwater flow direction and gradient because this data was used to prepare the 

associated groundwater flow/contaminant transport model used to support the Tier 3 Risk 

Assessment. In addition, a Tier 3 Risk Assessment re-evaluation was also conducted. The reevaluation required an assessment regarding the assumption that the maximum solubility of JP-5 

is 4,500 g/L (Attachment B). 

Although split samples from RHMW02 to be analyzed for TPH-DRO/TPH-gasoline range 

organics (GRO) and by the Massachusetts Department of Environmental Protection (MADEP) 

analytical protocol were not collected during Round 13, this was done during Round 16 (July 

2009). Consequently, the results obtained from Round 16 allowed for a detailed comparison 

analysis of total TPH-DRO/TPH-GRO concentration verses the total MADEP volatile petroleum 

hydrocarbons (VPH)/extractable petroleum hydrocarbon (EPH) concentration (Attachment C). 

This comparison showed that an overall average of approximately 27 percent of the TPH-DRO 

result was from polar, non-fuel organic compounds. 

This hypothesis is strengthened by an analysis of the TPH-DRO chromatographs for samples 

collected in January and February 2010. This TPH-DRO analysis showed that apparently nonfuel tentatively identified compounds (TICs) accounted for approximately 35 percent of the 

TPH-DRO concentration (Attachments B and D). These results strongly suggest that the TPHDRO results for RHMW02 collected during Round 13 did not exceed the assumed maximum JP5 solubility of 4,500 g/L and that approximately 1/3 of the TPH-DRO reported concentration 

was likely from less toxic, non petroleum-related compounds (Attachment E). 

The Tier 3 Risk Assessment also considered another critical factor of the 

groundwater/contaminant transport model (i.e., the simulated flow direction and gradient). As 

discussed in a previous section, a precision GPS elevation survey was done on all of the wells 

located out of the lower access tunnel that were used in the 2006 aquifer test. This data was used 

to compute the groundwater flow direction when the pumps at the US Navy Well 2254-01 were: 

 Not in operation; 

 Pumping at the maximum rate that could be sustained for five days; and 

 Pumping at a rate closely resembling normal withdrawal from that well. 

This analysis showed that there was flow in the assumed west-southwest direction parallel to the 

alignment of tanks, but it also showed a stronger flow component to the northwest. This 

deviation from the modeled groundwater flow direction and gradient does not significantly 

change the conclusions of the model. One of the sensitivity simulations performed and detailed 

in TEC (2007b) was a reduced flow scenario due to a drought. 

This reduced flow beneath the UST source area to the infiltration gallery of US Navy Well 2254-

01 was assessed. According to the model, the distance a dissolved plume traveled from a 

stationary free-product plume until natural attenuation had reduced the concentration to 100 g/L 

was 1,170 feet for the base simulation, but was reduced to 1,090 feet for the lower-flow drought 

simulation. This establishes that the Tier 3 Risk Assessment/groundwater model, while not 

reflecting the entire groundwater flow field, does simulate the most conservative flow direction. 

Therefore, with respect to the potential risk to the US Navy Well 2254-01, the results of the Tier 

3 Risk Assessment (TEC, 2007b) still remain valid. This is because the Tier 3 Risk Assessment 

assumes a worst case scenario, that the dominant groundwater flow direction places the 

infiltration gallery of 2254-01 directly down gradient from the USTs. 
7 

PROPOSED FUTURE COURSE OF ACTION

TPH-DRO results at RHMW02 exceeding the computed maximum solubility of JP-5 have 

occurred twice during the history of the groundwater monitoring program associated with the 

Facility. It is expected this situation will occur again in the future. If this does occur, a detailed 

chromatograph TICs evaluation similar to that done for the Round 18 samples should be 

requested from the lab. If the results indicate that the TPH fraction due to fuel hydrocarbons 

does exceed the computed solubility of JP-5 (4,500 g/L), another re-evaluation of the Tier 3 

Risk Assessment/groundwater model should be done. 

This re-evaluation should consist of investigating the validity of the 4,500 mg/L solubility limit 

and re-computing the distance from the edge of a free product plume to TPH-GRO/TPH-DRO 

compliance using the measured TPH concentration and a degradation rate of 0.007 per day. This 

is an average degradation rate computed using results from 23 Air Force fuel contaminated sites 

(Wiedemeier et al., 1999). Using this data, new SSRBLs could be established for the monitoring 

wells based on distance from the eastern end of the infiltration gallery for US Navy Well 2254-

01. 

It is further recommended that at least one more round of split samples be collected for TPHGRO/TPH-DRO and MADEP VPH/TPH analysis. This will help establish whether TPH-DRO 

concentrations that may be measured at the Facility’s non-potable wells (RHMW01, RHMW02, 

RHMW03, and RHMW05) are from fuel hydrocarbons or from polar, less toxic, non-fuel 

organic compounds. 

Of the wells previously listed, RHMW05 is of greatest concern because its TPH-DRO results 

have been consistently greater than the HDOH environmental action levels (EALs). Therefore, 

due to the close proximity of RHMW05 (i.e., located between RHMW01 and the US Navy Well 

2254-01, approximately 600 feet from the US Navy Well 2254-01), modified SSRBLs for TPHDRO and TPH-GRO for this well should be established and the Plan revised as appropriate. 
8 

References 

AMEC, 2002. Red Hill Bulk Fuel Storage Facility Investigation Report, Prepared for NAVFAC 

Pacific, August 2002. 

Dawson, 2005a. Groundwater Sampling, Red Hill Fuel Storage Facility, Hawaii, First Quarter 

2005. Dawson Group. April 2005. 

Dawson, 2005b. Groundwater Sampling, Red Hill Fuel Storage Facility, Hawaii, Second Quarter 

2005. Dawson Group. August 2005. 

Dawson, 2005c. Groundwater Sampling, Red Hill Fuel Storage Facility, Hawaii, Third Quarter 

2005. Dawson Group. November 2005. 

Dawson, 2006. Groundwater Sampling, Red Hill Fuel Storage Facility, Hawaii, Fourth Quarter 

2005. Dawson Group. February 2006. 

MADEP, 2002. Characterizing Risks Posed by Petroleum Contaminated Sites: Implementation 

of the MADEP VPH/EPH Approach, Policy #WSC-02-411 

TEC, 2007a. Red Hill Bulk Fuel Storage Facility Final Technical Report, Pearl Harbor, Hawaii. 

Prepared for NAVF AC Pacific. August 2007 

TEC, 2007b. Red Hill Bulk Fuel Storage Facility Final Technical Report, Pearl Harbor, Hawaii. 

Appendix K – Red Hill Bulk Fuel Storage Facility – Final Contaminant Transport 

Simulations Using Numerical Models for Tier 3 Risk Evaluation, Pearl Harbor, Hawaii. 

Prepared for NAVFAC Pacific. August 2007 

TEC, 2008. Red Hill Bulk Fuel Storage Facility Final Groundwater Protection Plan – Pearl 

Harbor, Hawaii. Prepared for NAVFAC Pacific. January 2008 

TEC 2009. Quarterly Groundwater Monitoring Report Red Hill Fuel Storage Facility – Pearl 

Harbor, Oahu, Hawaii. Prepared for Commander Navy Region Hawaii. February 2009 

TEC 2010. Quarterly Groundwater Monitoring Report Red Hill Fuel Storage Facility – Pearl 

Harbor, Oahu, Hawaii. Prepared for Commander Navy Region Hawaii. April 2010 

Wiedemeier, T.H., J.S. Rifai, C.J. Newell, and J.T. Wilson. 1999. Natural Attenuation of Fuels 

and Chlorinated Solvents in the Subsurface. J. Wiley and Sons, Inc. 
Attachment A 

Groundwater Letter Report 
1 

April 15, 2010 

Greg Yamasaki, P.E. 

FISC Pearl Harbor, Code 701 

1942 Gaffney Street, Suite 100 

Building 1757, 2nd Floor 

Pearl Harbor, HI 96860-4549 

Subject: Groundwater Flow Direction/Gradient and Tier 3 Risk 

Assessment Re-evaluation Letter Report 

Red Hill Bulk Fuel Storage Facility, Pearl Harbor, HI 

Contract #N47408-04-D-8514, Task Order 54 

1.1 INTRODUCTION

This Letter Report was prepared for the Naval Fleet Engineering Service Center (NFESC) and 

the Pearl Harbor Naval Base Fleet Industrial Supply Center (FISC) by TEC Inc. (TEC) under 

contract N47408-04-D-8514, Task Order 0054. Under Task Order 0054, TEC is providing 

environmental compliance services to FISC at the Red Hill Bulk Fuel Storage Facility (the 

Facility), associated with past releases of petroleum hydrocarbons to the subsurface bedrock and 

underlying groundwater aquifer. 

1.2 SITE DESCRIPTION

The Facility includes twenty 12.5 million-gallons (Mgal) underground storage tanks (USTs) 

located within Red Hill Ridge, Halawa Valley, Hawaii. The Facility also includes a series of 

tunnels and pipelines that deliver fuel to and from Pearl Harbor Naval Base (Figure 1). The 

Facility was constructed prior to World War II to support United States Naval activities in the 

Pacific. 

The USTs were constructed in the field using mining techniques, and are exempt from many 

Federal and State UST program requirements due to the field-constructed nature of the tanks. 

According to records, the main fuel types stored at the Facility have been diesel oil, Navy 

Special Fuel Oil (NSFO), Navy Distillate (ND), Jet Propulsion Fuels 5 and 8 (JP-5 and JP-8), 

and F-76 (diesel marine fuel). In addition, Tank 17 contained Aviation Gasoline (AVGAS) and 

Motor Gasoline (MOGAS) between 1964 and 1969, and Tank 18 contained AVGAS between 

1964 and 1968. A review of the Facility records, which were classified until 1995, has identified 

an ongoing maintenance and repair program conducted by the United States (U.S.) Navy. 

Environmental studies conducted between 1995 and the present (AMEC Earth and 

3 

Environmental Inc. [AMEC], 2002; Dawson Group Inc. [Dawson], 1995; TEC Inc., 2007; and 

others) have identified petroleum under a number of these USTs in soil vapor, rock samples, and 

groundwater that has been categorized as a drinking water resource by the HDOH (Mink and 

Lau, 1990). This poses a potential threat to downgradient drinking water wells. 

The Facility is approximately 100 feet above the basal water table on the boundary of the 

Waimalu and Moanalua Aquifer Systems of the Pearl Harbor and Honolulu Aquifer Sector, 

respectively. Both aquifers are sources of potable water for several public water systems, 

including the Honolulu Board of Water Supply (HBWS) well 2354-01 (Halawa Shaft); wells 

2153-10, 2153-12, and 2153-22 (HBWS Moanalua wells); and the U.S. Navy Well 2254-01 

(Figure 2). Most notably, the U.S. Navy Well 2254-01, located approximately 3,000 feet from 

Facility USTs, is permitted to pump 4.6 million gallons per day (mgd) of potable water from a 

submerged infiltration tunnel which extends approximately 1,280 feet across the water table and 

supplies the Pearl Harbor Water System. Historical estimates of the hydraulic gradient within 

these aquifers assumed that the U.S. Navy Well 2254-01 is located directly downgradient from 

the Facility and is at the greatest risk for contamination from fuel releases from the Facility. 

1.3 BACKGROUND

1.3.1 Summary of Previous Gradient Analysis 

EarthTech (EarthTech, 2000) performed gradient analysis using wells at the Oily Waste Disposal 

Facility (OWDF) installed for a Remedial Investigation (RI). This analysis showed a 

groundwater flow direction that varied from nearly due east to northeast, depending on the 

magnitude of the groundwater withdrawal from the U.S. Navy Well 2254-01. The gradient 

varied from 0.00038 to 0.00048 ft/ft. TEC (TEC, 2007) did a gradient analysis based on wells 

located in the Facility. This analysis showed a groundwater flow direction to the northnorthwest when the drinking water well pumps were operating at full capacity (approximately 

304 degrees from north) and to the south when the pumps were not in operation (approximately 

179 degrees from north). The previous site conceptual model assumed that groundwater in the 

area flowed parallel to the Red Hill Ridge (approximately 240 degrees from north) without the 

influence of pumping, and in the direction of the U.S. Navy well 2254-01 infiltration gallery 

(approximately 270 degrees from north) when U.S. Navy well 2254-01 is pumping at full 

capacity. 

Both of these analyses used wells that were relatively closely spaced where the distance between 

wells varied from 815 ft to 4490 ft. Since groundwater gradients in the study area are relatively 

small, usually on the order of 2 x 10-4 ft/ft to 4 x 10-4 ft/ft, a small error in the measurement of 

the groundwater elevation at any well can result in a significant shift of the computed 

groundwater flow direction from the true value. Also, only using on-site wells does not show the 

influence of the regional groundwater flow direction and gradient in the area. 

An analysis of the regional groundwater flow in the study area was conducted as part of the 

aquifer test and modeling performed by TEC and the University of Hawaii (UH) by Rotzoll and 

El-Kadi (Rotzoll and El-Kadi, 2006). This test included wells owned by the HBWS and State of 

Hawaii Commission on Water Resources Management (CWRM), as well as the on-site wells. 

For this regional test, four on-site wells (OWDF-MW1, RHMW02, RHMW03, and RHM04) and 

three regional wells (Halawa Deep Observation well, CWRM Deep Monitoring Well, and 
Figure 2. 

Area Wells and Aquifer SystemsGroundwater Gradient Study Red Hill Bulk Fuel Storage Facility, Pearl Harbor, Hawaii

Waimalu SystemPearl Harbor Aquifer Sector

Moanalua SystemHonolulu Aquifer Sect
5 

TAMC-MW2 well) were instrumented with pressure sensing data loggers that provided longterm water elevation versus time data at each well. This data was augmented by daily averaged 

water table elevations measured at two HBWS wells, one in Moanalua Valley (Manaiki 

Observation Well) and the other in north Halawa Valley (Halawa Shallow Observation Well). 

Figure 3 shows the location of the wells used in this aquifer test. 

During the test, the pumps at the U.S. Navy Well 2254-01 infiltration gallery were shut off for 

five days, and then pumped at a maximum sustainable rate for four days. The goal of the test was 

to estimate the hydraulic parameters of the aquifer by matching the field measured water table 

variations with the output of the groundwater flow model. A good match was developed 

between the measured and simulated variations in water table elevation, but there were 

significant differences in the absolute value of the water table elevation. In the report (Rotzoll 

and El-Kadi, 2006), these differences were noted in the graphs as offset values used to 

superimpose the model results on the measured data (Figure 4). One potential source of the 

difference between the absolute values of measured and simulated water levels was thought to be 

potential errors in TOC elevation measurements from the various wells used in the study. For 

example, the TOC elevations used for the three HBWS observation wells had been measured at 

different times from the TOC elevation for the CWRM Deep Monitoring Well. These wells did 

not have a single control point of reference or common datum. Also, water level data from these 

off-site wells were used to calibrate the regional flow model that defined the simulated flow 

regime in the study area, therefore, any error related to an inconsistent datum would have an 

effect on the absolute water table elevations in the calibrated model. 

It was also noted that inconsistent reference points, or other errors associated with prior surveys, 

would affect the calculated hydraulic gradient direction and magnitude, which were inconsistent 

with expected results (see above). 

1.4 SURVEY OF REGIONAL AND ON-SITE WELL TOC ELEVATIONS

To resolve the uncertainties associated with inconsistent survey reference points and the resulting 

effects on groundwater flow direction, a set of surveys was conducted to reference all 

measurements to a common datum. This was done with a Global Positioning System (GPS) 

survey for wells capable of receiving a satellite signal, and an optical survey to tie the GPS 

survey to the wells located in the lower access tunnel within the Facility. 

On September 29, 2009, Pacific GPS was contracted by the U.S. Navy through TEC to survey 

the TOC elevation of all wells with a clear view of the sky using GPS technology. The Pacific 

GPS report is included as Attachment A to this letter report. A short summary of the process and 

results are given here. As part of the study, a base station GPS instrument was placed near 

OWDF-MW1. This provided a known location to reference all other GPS measurements (a 

common datum). GPS signals are altered by atmospheric conditions, which must be accounted 

for to get the most accurate measurements. Data recorded at a GPS base station at a known 

location allows the effect of atmospheric distortion to be calculated and removed from the GPS 

signals collected at unknown locations, thus providing an atmospheric correction. 

During the study, the base station was in radio communication with the “rover” station, which 

measured the northing, easting, and elevation of the other wells. During the course of the survey, 
RHMW02

RHMW04

RHMW03

OWDF-MW1

TAMC-MW2

Manaiki Obs. Well

2254-01Infiltrationgallery

Halawa Deep Obs.Halawa Shallow Obs.

CWRMDeep Mont.

Figure 3 Locations of Wells Used in the 2006 Aquifer Test and Current Groundwater Flow Direction AGroundwater Gradient Study Red Hill Bulk Fuel Storage Facility, Pearl Harbor, Hawaii

HBWS

Major Roads Halawa ShaftAquifer Boundaries

Legend
Figure 4 

Offset Required to Match Simulated Water Levels to Measured Water Levels (Rotzoll and El-KGroundwater Gradient Study Red Hill Bulk Fuel Storage Facility, Pearl Harbor, Hawaii
8 

a recently validated survey bench mark, monument CHIGUI, was found near the site. The 

elevation of a temporary bench mark outside of Adit 3 was established in relationship to 

monument CHIGUI, becoming the central reference point or common datum for this survey. 

Table 1 below shows the assumed elevation and revised elevation of each surveyed point. For 

the purposes of the groundwater gradient evaluation it was important that all wells were 

referenced to a common datum. The datum selected for this study was Mean Tidal that was used 

for benchmark CHIGUI. Prior to the submission of the project summary report, the difference 

between the Mean Tidal vertical datum and NAVD 29 Mean Sea Level datum will be 

investigated and all TOC elevations will be referenced the NAVD 29 Mean Sea Level datum. 

Table 1. GPS Survey Results Compared With Previously Surveyed TOC Elevations 

Well Name 

State Well 

No. 2006 TOC Elev. 

2009 GPS 

TOC Elev. 

Elevation 

Difference

Datum 

NAVD 29 Mean 

Sea Level Mean tidal 

 (ft above datum) 

(ft above 

datum) (ft) 

RHMW04 - 313.03 312.34 -0.69 

OWDF-MW1 - 138.94 138.38 -0.56 

TAMC MW-2 - 179.91** 179.65 -0.26 

CWRM Deep Mont. Well 2253-03 226.68 226.96 0.28 

Halawa Deep Obs. Well 2255-40 60.00** 60.43 0.43 

Halawa Shallow Obs. Well 2255-33 58.01 58.24 0.23 

Manaiki Obs. Well 2153-09 61.05 61.26 0.21 

 

Note: ** indicates estimated TOCs used in 2006 data set, not based on survey data. 

Notes: 

GPS – Global Positioning System 

TOC – Top of Casing 

No.- Number 

Elev.- Elevation 

NAVD 29 – North American Vertical Datum, 1929 

ft.- feet 

The new GPS survey with the common datum resulted in changes in the relative TOC elevations 

between measured wells as shown in Table 1. For example following the survey, the water 

elevation difference between RHMW04 and OWDF-MW1 changed by 0.13 ft, whereas, the 

water elevation difference between RHMW04 and the CWRM Deep Monitoring Well changed 

by 0.97 ft. TEC could not find reliable elevation data for TAMC-MW2 and Halawa Deep 

Observation Well for the 2006 data set, so the previously used elevations were estimates. The 

2009 GPS survey data are considered survey grade for these locations. 
9 

Table 2. Comparison of TOC elevations Used since 2006 and the Updated TOC Elevations 

Based on the GPS Survey and the 2009 Optical Survey 

Well Name 2006 TOC Elev. 2010 Optical Elev. 

Elevation 

Difference 

Datum NAVD 29 Mean Sea Level Mean tidal 

 (ft above datum) (ft above datum) (ft) 

OWDF-MW1 138.94 138.38 -0.56 

RHMW01 102.51 102.27 -0.24 

RHMW02 105.01 104.76 -0.25 

RHMW03 121.31 121.06 -0.25 

RHMW05 NA 101.55 NA 

Notes: 

GPS – Global Positioning System 

TOC – Top of Casing 

No.- Number 

Elev.- Elevation 

NAVD 29 – North American Vertical Datum, 1929 

ft.- feet 

On March 21 and March 22, 2010, a closed-loop optical survey was conducted of RHMW01 and 

RHMW05 within the Facility tunnel using OMDF-MW1 as the reference elevation. RHMW01 

was also surveyed as part of the Remedial Investigation in 2006, as were RHMW02 and 

RHMW03. The 2006 TOC elevations of RHMW02 and RHMW03 were adjusted based on the 

elevation difference measured between the 2006 and 2010 surveys of well RHMW01. The 

results of the 2006 and the 2010 surveys are included with this report as Attachments B and C 

respectively. 

 

1.5 REVISED GROUNDWATER FLOW DIRECTION AND GRADIENT

1.5.1 Geometric Calculations 

The recent GPS and optical surveys referenced the TOC measuring point at each surveyed well 

to a common vertical datum. Using the revised TOC elevation data, the on-site groundwater 

flow direction and gradient were re-evaluated using previously collected groundwater elevation 

measurements. This was done for the three different pumping conditions created during the 

2006 aquifer test (TEC, 2007). The data were collected during the following conditions and 

dates: 

 May 18, 2006 when the pump in the U.S. Navy Well 2254-01 had been shut off for 5 

days; 

 May 25, 2006 when the pumps in the U.S. Navy Well 2254-01 had been pumping a 

maximum sustainable rate of approximately 10 mgd for 4 days; and 

 May 30, 2006 when the pumps in the U.S. Navy Well 2254-01 had been pumping at a 

normal rate (about 4 mgd) for 5 days. 

The groundwater flow direction and gradient computed from on-site wells were evaluated and 

compared to that computed in 2007 (TEC, 2007). The analysis was done using the EPA gradient 
10 

calculation website (http://www.epa.gov/athens/learn2model/part-two/onsite/gradient4plusns.html ). Wells RHMW02, RHMW03, RHMW04, and OWDF-MW1 were used in this 

analysis. These are the same wells used in the previous TEC report (2007) except that OWDFMW1 was used instead of the U.S. Navy Well 2254-01. This was done because the EPA 

gradient calculation website assumes the data entered are from point sources and the water level 

measured at U.S. Navy Well 2254-01 is reflective of the water level in the infiltration gallery, a 

long linear source. Table 3 below compares the two sets of flow direction and gradient 

calculations for the dates selected. 

Table 3. Groundwater Flow Direction and Gradient for Wells Located on the Facility 

Computed in 2006 and 2010 

Date (TEC, 2006) (TEC, 2010) 

 Flow 

Direction1

Gradient 

(ft/ft) 

Flow 

Direction1

Gradient 

(ft/ft) 

May 18, 2006 180 0.00051 270 0.000089 

May 25, 2006 306 0.0024 270 0.00015 

May 30, 2006 184 0.00051 270 0.000093 

Notes: 

1

 – degrees measured from north, clockwise 

ft/ft – Hydraulic gradient as feet per feet, rise to run 

The substitution of OWDF-MW1 for 2254-01 excludes the large localized water level variations 

in 2254-01 that result from pump drawdown. With the revised TOC elevations and excluding 

the monitoring well 2254-01, the groundwater flow direction is to the west and the gradient is 

much shallower. To properly include the impact of the drinking water shaft on the water table 

elevation requires a two-dimensional contouring program, as described below. 

1.5.2 Two-Dimensional Contouring 

Calculating groundwater flow direction and gradient assumes that the points fit nicely into a 

plane. In reality this is rarely the case and the Red Hill region is no exception. To get a more 

accurate representation of the groundwater elevation surface, the well data were contoured using 

the Triangular Irregular Network (TIN) module of the Groundwater Modeling System (GMS). 

This software is actually a suite of the leading groundwater modeling codes. The MODFLOW 

and RT3D modules of GMS were used to perform the Tier 3 risk analysis modeling for this site 

(TEC, 2007). For the problem at hand, a polygon was digitized that encompassed the wells that 

were used in the regional flow analysis. The polygon was converted to TIN and the water level 

data from the wells was interpolated to the TIN using the natural neighbor method (Figure 5). 

This method looks “beyond” the boundary of the enveloping polygon to prevent errors at the 

edge of the TIN. Data for May 18, 25, and 30, 2006 were contoured and are shown in Figures 6 

through 8 respectively. Water levels used for the contouring were from wells: 

 OWDF-MW1; 
Figure 5. 

TIN Used to Contour the Water Table at the Red Hill RegionGroundwater Gradient Study Red Hill Bulk Fuel Storage Facility, Pearl Harbor, Hawaii

U.S. Navy Well 2254-01

HBWS Halawa Shaft

ContouringTIN

HoAq

Pearl HarborAquifer

Major RoadsAquifer Boundaries

Legend
Figure 6. 

Groundwater Elevation Contours Based on Water Levels Measured On May 18, 2006 (contour groundwater elevations at each well shown in ft above mean tidal datum)Groundwater Gradient Study Red Hill Bulk Fuel Storage Facility, Pearl Harbor, Hawaii

RHMW0220.29

RHMW0420.56

RHMW0320.33

OWDF-MW120.06

TAMC-MW221.01

Manaiki Obs. Well21.43

2254-0120.17

Major RoadsAquifer Boundaries

Legend
Figure 7. 

Groundwater Elevation Contours Based on Water Levels Measured On May 25, 2006 (contour groundwater elevations at each well shown in ft above mean tidal datum)Groundwater Gradient Study Red Hill Bulk Fuel Storage Facility, Pearl Harbor, Hawaii

RHMW0219.41

RHMW0420.01

RHMW0319.78

OWDF-MW119.13

TAMC-MW220.75

Manaiki Obs. Well21.18

2254-0114.29

Major RoadsAquifer Boundaries

Legend
Figure 8. 

Groundwater Elevation Contours Based on Water Levels Measured On May 30, 2006 (contour groundwater elevations at each well shown in ft above mean tidal datum) (Blue arrows show intgroundwater flow directions)Groundwater Gradient Study Red Hill Bulk Fuel Storage Facility, Pearl Harbor, Hawaii

RHMW0220.13

RHMW0420.49

RHMW0320.37

OWDF-MW119.95

TAMC-MW220.99

Manaiki Obs. W21.39

2254-0119.57

Major RoadsAquifer Boundaries

Legend
15 

 U.S. Navy Well 2254-01 (represented as a shaft by a series of closely spaced data points); 

 RHMW02; 

 RHMW03; 

 RHMW04; 

 TAMC-MW2; and 

 The Manaiki Observation Well. 

The Halawa observation wells were not included because there is an intervening flow barrier, 

probably the north Halawa valley fill, between these wells and the Facility, as observed in results 

of the 2006 aquifer test (TEC, 2007). CWRM Deep Monitoring Well was not included because 

of questionable water level elevations measured at this well. A recent evaluation of 

measurements taken during the 2006 aquifer test has shown a two-foot difference between the 

water elevations measured in the main CWRM well and co-located piezometer. The cause of 

this discrepancy has not been determined. 

Assuming that the aquifer directly beneath the study area is horizontally isotropic, in which the 

hydraulic conductivity is the same regardless of the flow direction, groundwater will flow in a 

direction perpendicular to the groundwater equal-elevation contours. The data set is sparse, 

particularly at the southeast end of the polygon, but a generalized flow pattern becomes evident. 

In Figure 6, the data show that groundwater flows from southeast to the northwest. 

Figure 7 shows the water table surface on May 25, 2006, when the pumps in the infiltration 

gallery at U.S. Navy Well 2254-01 are pumping at full capacity (approximately 10 mgd). As 

shown, there is a significant drawdown at the infiltration gallery increasing the southwestly 

groundwater flow component. However, a west-northwest regional flow component is evident in 

the vicinity of the USTs. 

Figure 8 shows the water table surface on May 30, 2006, when pumps at the U.S. Navy Well 

2254-01 were operating at normal capacity (approximately 4 mgd). On this figure arrows are 

drawn to show the dominant groundwater flow directions. In the vicinity of the USTs, as before, 

the gradient indicates a regional component of groundwater flow to the west northwest and a 

local component to the southwest. The gradient east of the Facility is approximately 0.00028 to 

the northwest. At the Facility and U.S. Navy Well 2254-01 there is a localized gradient of 

approximately 0.00022 to the southwest, less than one-tenth of the magnitude of the regional 

gradient. 

1.6 IMPLICATIONS FOR THE TIER 3 RISK ASSESSMENT 

The revised groundwater flow direction and gradient does not invalidate the Tier 3 Risk 

Assessment detailed in Appendix K of TEC (2007) that evaluates the Navy drinking water well 

2254-01 as the receptor of concern. The groundwater model is the key component of the Tier 3 

risk assessment that required re-evaluation based on recent information. Other assumptions and 

calculations used in the Tier 3 model have not changed. The model assumes a “mauka to makai” 

flow that runs parallel to the alignment of tanks, placing the northeast portion of the drinking 
16 

water well 2254-01 directly down gradient from the underground storage tanks (USTs). This is 

the most conservative approach and most protective of the drinking water source. 

The northwest regional flow places the HBWS Halawa Shaft, a major drinking water source for 

south Oahu, down gradient from the USTs. Results from a regional groundwater test in 2006 

indicate no good hydraulic connection between wells on the northern edge of Halawa Valley and 

pumping from U.S. Navy Well 2254-01. Figure 9 shows the water levels monitored during the 

aquifer test. All wells monitored showed a good response to the induced drawdown at U.S. 

Navy Well 2254-01 (blue-green line) except the Halawa Deep and Shallow Observation wells. 

Figure 10 shows the well arrangement for this test and the locations of the valley fills that may 

pose a barrier to groundwater flow. The probable cause of this poor connection is thick 

sediments that have filled in the North Halawa Valley to depths well below the water table. In 

addition, the modeled natural attenuation rate indicates that the HBWS Halawa Shaft would not 

be threatened from a petroleum release from the Facility unless a free product plume moved in 

the direction of the HBWS Halawa Shaft. To date no free product plume has been detected. 

 

1.7 CONCLUSIONS AND RECOMMENDATIONS

A re-evaluation of the groundwater flow direction and gradient in the vicinity of the Red Hill 

Facility shows a local flow direction from the USTs toward the drinking water well 2254-01 as 

expected. The gradient for this flow direction is approximately 0.00022 ft/ft. This evaluation 

also shows a regional component flowing to the northwest. The gradient for this flow direction 

is approximately 0.00028. With respect to the potential impact to the U.S. Navy Well 2254-01, 

the results of the Tier 3 Risk Assessment (TEC, 2007) still remain valid. It assumes a worst case 

scenario that the dominant groundwater flow direction places the infiltration gallery of 2254-01 

directly down gradient from the USTs. 

The northwest regional component of the groundwater flow may be transporting a petroleum 

plume or dissolved hydrocarbons in a direction that is not currently being monitored. Currently 

there are no compliance wells between the Halawa Shaft and the Facility to evaluate this 

possibility. For the HBWS Halawa Shaft to be threatened by contamination from the Facility a 

free product plume would have to be present within approximately 1200 ft of this drinking water 

source. The CWRM Deep Monitoring Well is not suitable for detecting a free product plume 

since the solid casing of this well extends about 50 ft below the water table. RHMW04 is not 

ideally located to monitor a northwest plume because it is located northeast of the USTs. In 

order to ensure petroleum components are not moving off-site along the northwest groundwater 

flow direction, it is recommended that at least two monitoring wells be installed to monitor any 

contamination that may be migrating off-site in that direction. 
Figure 9. 

Recorded Water Levels in Wells Monitored During the May 2006 Aquifer Test at Red Hill UpdTOC ElevationsGroundwater Gradient Study Red Hill Bulk Fuel Storage Facility, Pearl Harbor, Hawaii
RHMW02

RHMW04

RHMW03

OWDF-MW1

TAMC-MW2

Manaiki Obs. Well

2254-01Infiltrationgallery

Halawa Deep Obs.Halawa Shallow Obs.

CWRMDeep Mont.

Figure 10 Locations of Monitoring and Observations Wells, and the Locations of Potential Barriers to GGroundwater Gradient Study Red Hill Bulk Fuel Storage Facility, Pearl Harbor, Hawaii

South Halawa

Valley Fill

North Halawa Valley Fill

Moanalua

Valley Fill Aliamanu and Salt Lake Tuff Cones

Coastal Caprock

Kalihi Valley F

Major RoadsAquifer Boundaries

Legend
19 

This letter report presents an interpretation of the groundwater flow direction and gradient in the 

Red Hill Bulk Fuel Storage Facility study area and surrounding region. The surrounding areas 

were included to assess what influence regional flow might have on contaminant transport from 

the facility. If you have any questions, please contact me at (808) 528-1445 or Rick Adkisson at 

that number or via his cell phone at (865) 742-2181. 

Sincerely, 

TEC Inc. 

Robert B. Whittier 

Senior Hydrogeologist 

Att: Attachments A, B, and C 

 

cc: Raelynn Della Salla 

 Robert Campbell 

 Carol Vollmer 

 
20 

References 

AMEC, 2002. Red Hill Bulk Fuel Storage Facility Investigation Report, Prepared for NAVFAC 

Pacific, August 2002. 

Dawson, 2005a. Groundwater Sampling, Red Hill Fuel Storage Facility, Hawaii, First Quarter 

2005. Dawson Group. April 2005. 

Dawson, 2005b. Groundwater Sampling, Red Hill Fuel Storage Facility, Hawaii, Second 

Quarter 2005. Dawson Group. August 2005. 

Dawson, 2005c. Groundwater Sampling, Red Hill Fuel Storage Facility, Hawaii, Third Quarter 

2005. Dawson Group. November 2005. 

Dawson, 2006. Groundwater Sampling, Red Hill Fuel Storage Facility, Hawaii, Fourth Quarter 

2005. Dawson Group. February 2006. 

Rotzoll, R. and A.I. El-Kadi, 2006. Numerical Ground-Water Flow Simulation For Red Hill 

Fuel Storage Facilities, NAVFAC Pacific, Oahu, Hawaii. Prepared for TEC by The 

University of Hawaii. 81 pgs. August 2007 

Mink, J.F. and L. L. Lau, 1990. Aquifer Identification and Classification for O’ahu: GroundWater Protection Strategy for Hawaii. Water Resources Research Center, University of 

Hawaii at Manoa. February 1990. Revised 

TEC, 2007. Red Hill Bulk Fuel Storage Facility Final Technical Report, Pearl Harbor, Hawaii. 

Prepared for NAVFAC Pacific. 142 pages and Appendices. August 2007 
21 

Attachment A 

GPS Elevation Survey of Red Hill Area Wells 
www.pacificgps.com

info@pacificgps.com

758 Kapahulu Ave. #548

Honolulu, HI 96816-1198

808.538.PGPS (7477)

877.538.PGPS (7477)

Fax: 808.988.2522

October 13, 2009

Bob Whittier

Richard Adkisson

TEC, Inc.

1001 Bishop St., 1400 ASB Tower

Honolulu, HI 96813

Phone: (808)528-1445

Email: rbwhittier@tecinc.com

RE: ELEVATION SURVEY, RED HILL FUEL STORAGE FACILITIES

Bob and Richard,

This letter presents our findings for the elevation survey performed at the well heads located on

and around the Red Hill area. The survey was performed using Trimble’s survey grade GPS

systems including an R7GNSS base station and R8GNSS rover receiver. The data was processed

in Trimble Business Center software, version 2.1.

A GPS Base station was setup in the middle of the project area, close to well OWDFMW1. An

RTK survey was conducted for each point with a minimum occupation time of 5 minutes at each

well location except for the Maniki well. The Maniki well position was derived by collecting two

independent 5 minute static survey sessions and post processing this data with GPS data collected

at the base station. The vertical precision value is derived based on a 95% confidence level.

Observation locations were taken on the “north notch” of each well casing, where feasible. The

well elevations for 2255-40, Halawa Shallow, and Maniki were calculated by taking a GPS

observation at a location in the immediate vicinity and utilizing a level between the well casings

and observation points.

Table 1 presents the well and associated point elevations in Hawaii State Plane, Zone 3, NAD 83

coordinates and both WGS-84 ellipsoidal heights (referenced to NAD 83) and Local Tidal

elevations. The ellipsoidal heights were determined by the GPS observations. Local Tidal

elevations were determined by referencing NGS class I monument CHIGUI and using Geoid

model GEOID03. The NGS monument CHIGUI datasheet is attached for reference.
www.pacificgps.com

info@pacificgps.com

As a check for our base station location, a five hour static observation was recorded at the base

and processed using the NGS Online Positioning User Service (OPUS). The OPUS results were

based on rapid ephemeris information and were within our GPS derived base position by 0.032

feet in the vertical direction.

Table 1 - Red Hill Well Elevation Survey, (US Survey feet)

Well or Point Name Northing Easting

Local Tidal

Elevation

Ellipsoid

Height

Vertical

precision Description

ADIT3 74266.086 1671830.745 116.19 169.58 0.016 Nail in asphalt west of tunnel

RHMW04 75743.087 1677348.858 312.34 365.72 0.059 North Notch

OWDFMW1 74113.189 1672000.653 138.38 191.77 0.043 North Notch

2253-03 75654.495 1675870.469 226.96 280.34 0.046 North Notch

USGS Monument 74940.778 1667222.854 59.36 112.75 0.036 Monument at well 2255-40

2255-40 60.43 113.82 0.043 well casing

Halawa Shallow 58.24 111.62 0.043 well casing

TBM Maniki 68011.522 1678441.522 61.05 114.44 0.039 Nail 5' NW of Hydrant

Maniki 61.26 114.65 0.046 well casing

TAMC MW-2 71048.658 1675661.519 179.65 233.04 0.033 North Notch

Mon CHIGUI 73997.195 1668571.178 83.76 137.15 class 1 Monument, from datasheet

GPS Base Station 74143.366 1672049.537 137.38 190.76 0.032 Nail, NE of OWDFMW1

An updated Geoid model, GEOID 09, was recently made available by the National Geodetic

Survey. The elevation difference between models GEOID03 and GEOID09 vary from 0.49 to

0.54 feet in the study area. Table 2 lists the values for GEOID03 and GEOID09 and the

difference in values for each location.
www.pacificgps.com

info@pacificgps.com

Table 2 - Red Hill Well, Geoid Values (US Survey Feet)

Well or Point Name GEOID 03 Height GEOID 09 Height

GEOID03 -

GEOID09

ADIT3 51.90 51.37 0.53

RHMW04 52.19 51.64 0.54

OWDFMW1 51.90 51.37 0.53

2253-03 52.11 51.58 0.53

USGS Monument 51.75 51.21 0.54

2255-40 51.75 51.21 0.54

Halawa Shallow 51.75 51.21 0.54

TBM Maniki 51.91 51.41 0.50

Maniki 51.91 51.41 0.50

TAMC MW-2 51.90 51.41 0.49

Mon CHIGUI 51.77 51.23 0.54

GPS Base Station 51.90 51.37 0.53

Thank you for the opportunity to assist you in this project. Please call or email with any

questions or comments.

Sincerely,

Ryan McGrath

Director of Survey

Pacific GPS

(808) 538-7477

mcgrath@pacificgps.com
22 

Attachment B 

2006 Survey of On-Site Wells 
2006 On-Site Well Survey

Pearl Harbor Control Network Hawaii State Plane

Unit: Feet

Point 

Number Northing Easting Elevation Description

1 75742.64 1677345.57 RHMW-04

312.83 RHMW-04 ground

313.03 RHMW-04 top casing

312.57 RHMW-04 top gauge

2 74041.08 1675059.16 RHMW-01

102.33 RHMW-01 conc

102.51 RHMW-01 top of casing

102.41 RHMW-01 gauge

3 74282.05 1675639.24 RHMW-02

105.64 RHMW-02 conc

105.67 RHMW-02 top cover

105.01 RHMW-02 gauge

4 74610.90 1676391.37 RHMW-03

122.06 RHMW-03 conc

122.11 RHMW-03 top rim

121.31 RHMW-03 gauge

5 74006.92 1672560.73 2254-01

105.79 2254-01 top cover

105.76 2254-01 gauge "N"

105.75 2254-01 gauge "S"

6 74202.61 1671757.38 MW9

116.79 MW9 brass disk

116.20 MW9 ground

119.35 MW9 top casing

118.91 MW9 gauge

7 74112.75 1671997.36 MW8

138.94 MW8 top casing

136.66 MW8 conc.

138.57 MW8 gauge

Horizontal Datum: NAD 83

Vertical Datum: NAVD 29 Mean Sea Level

Bulk Fuel Storage Facilities Risk Assessment

Red Hill Fuel Storage Facilities

D:\Admin\TEC\Red Hill\Well geographic data
23 

Attachment C 

Results of 2010 Optical Survey 
RED HILL FUEL STORAGE FACILITIES, NAVFAC PACIFIC

DESCRIPTION NORTHING EASTING ELEVATION

ADIT3 74266.09 1671830.75 116.19

ENTER 74222.06 1672009.76 114.50 Mag Nail at Entrance

OWDFMW1 74113.19 1672000.65 138.35 Top of 4" PVC 

RHMW01 74041.12 1675062.48 102.32 Top of Cover

102.21 Top of 1" PVC

RHMW05 73690.63 1674268.20 101.97 Top of Cover

101.52 Top of 2" PVC

Note:

Units: U.S. Feet

Coordinates were established from Stations ADIT3 and GPS Base Station as

established by Pacific GPS.

Elevations are based on a local tide and are referred to Station ADIT3 having an

elevation of 116.19 feet as established by Pacific GPS.

Underlined elevation was established by RMTC using differential leveling from

Station ADIT3.

2010 On-Site Well Survey
Attachment B 

Risk Assessment/Groundwater Re-evaluation Considerations
Tier 3 Risk Assessment/Groundwater Re-evaluation Considerations 

The Facility SSRBL (i.e., 4,500 g/L for TPH) established by the Tier 3 Risk 

Assessment/groundwater model (Tier 3 RAGWM) was based on the following assumptions: 

1. the concentration of dissolved fuel hydrocarbons in the groundwater is limited to 4,500 

g/L, the computed maximum solubility resulting from JP-5 fuel in direct contact with 

the groundwater surface; 

2. that the groundwater flows “mauka to makai”(i.e., mountain to ocean), a direction that 

places the U.S. Navy Well 2254-01 directly down gradient from the USTs; and 

3. the dissolved fuel hydrocarbons will degrade at a rate that was modeled using the reactive 

transport model code RT3D (the modeled bulk degradation rate was about 0.009 per 

day).

A TPH-DRO average concentration observed during Round 13 (October 2008) between the 

normal and duplicate sample of 5,420 g/L at RHMW02 tends to indicate that Assumption 2 

above could be invalid because no free product has been measured during monthly monitoring. 

To answer these and other related questions, a re-evaluation of the Tier 3 RAGWM was 

performed. This re-evaluation looked at three basic questions: 

1. Is the assumption that 4,500 g/L is the maximum possible TPH concentration resulting 

from a release of JP-5 to the water table still valid? 

2. Was the modeled groundwater flow direction correct? 

3. If either of the two preceding assumptions is found to be invalid, what impact does this 

have on the risk posed to drinking water sources by contamination from the USTs at the 

Facility? 

If Assumption 1 above is correct, the October 2008 TPH-DRO average concentration of 5,420 

g/L implies that petroleum product was directly in contact with groundwater in the vicinity of 

RHMW02 and that groundwater samples at that RHMW02 may contain un-dissolved product. 

However, oil-water interface measurements collected at RHMW02 did not detect measurable 

product at this location. If Assumption 1 was determined to be invalid, this would indicate that 

the modeled distance a dissolved plume would travel beyond a stabilized free-product plume 

prior to the TPH concentration degrading to less than the HDOH EAL concentrations could be 

erroneous. 

Question 1 - Maximum TPH Solubility Assessment

To answer these questions, various studies and evaluations were undertaken. The first study 

involved dual analysis of the groundwater collected from certain Facility wells. This included the 

TPH-DRO and TPH-GRO analysis that has been part of field sampling protocol since long-term 

monitoring started at the Facility. A second analysis was done using a protocol developed by the 

Massachusetts Department of Environmental Protection (MADEP) [MADEP, 2002]. This 

analysis breaks down TPH into two categories with each divided into three different fractions 

based on a range of carbon numbers (C). The breakdown is as follows: 

 Volatile Petroleum Hydrocarbons (VPH) includes the TPH compounds that range from 

C5 to C12 and are subdivided into: 

o C5-C8 aliphatics 

o C9-C10 aromatics 
o C9-12 aliphatics, but omits benzene, ethylbenzene, toluene, xylenes, (BTEX) 

methyl tert-butyl ether (MTBE), and naphthalene 

 Extractable Petroleum Hydrocarbon (EPH) includes TPH compounds that range from C9 

through C26 and are subdivided into: 

o C11-C22 aromatics 

o C9-C18 aliphatics 

o C19-C36 aliphatics, but omits the 17 polycyclic aromatic hydrocarbons (PAHs) 

analyzed using Method SW8270SIM 

The MADEP VPH analysis covers a slightly larger carbon range than TPH-GRO (VPH covers 

C5-C12, while TPH-GRO covers C6-C10). The MADEP EPH analysis covers the carbon range 

of C9-C36, while TPH-DRO is generally limited to the carbon range of C9-C26. 

Another major difference between TPH-DRO analyzed using method SW8015B and MADEP 

EPH analysis is a silica gel filtering step. Fuel hydrocarbons that dissolve into groundwater from 

fuels are non-polar while naturally occurring organics and less toxic hydrocarbon breakdown 

byproducts are polar compounds. The MADEP EPH analysis adds a silica gel column in the 

analysis string that removes the polar compounds from the sample aliquot effectively removing 

these interfering, less toxic breakdown compounds. 

In Round 16 (July 2009), the US Navy included MADEP VPH/EPH fractionation analyses along 

with TPH, to better understand the chemistry of the TPH plume under the Facility, and to reassess the risk associated with the plume. Additional TPH fractions can be evaluated for risk 

because MADEP has determined toxicity reference doses (RfDs) for these specific fractions that 

make up the TPH-GRO and TPH-middle distillate ranges (TPH-DRO). For Round 16, MADEP 

fractions for VPH and EPH were measured along with TPH-GRO and TPH-DRO in split 

samples from RHMW01, RHMW02, and RHMW03. 

The results from samples collected at RHMW02 showed that an overall average of 

approximately 27 percent of the TPH-DRO result was from polar, non-fuel organic compounds 

(Table 1). If this 27% average was used to adjust the observed average for only fuel-related 

compounds, then the TPH-DRO Round 13 concentration of 5,420 g/L would be reduced to 

3,957 g/L. This analysis strongly suggests the actual observed concentration of fuel 

hydrocarbons at RHMW02 is less than the computed maximum solubility of 4,500 g/L. 

Therefore, the established SSRBL for TPH of 4,500 g/L appears to be valid. 
Table 1. Total Petroleum Concentrations, MADEP Compared to USEPA Method 8015 

Monitor Well 

ID1

MADEP VPH2

(g/L) 

TPH-GRO4

(g/L) 

MADEP EPH3

(g/L) 

TPH-DRO5

(g/L) 

Average6

Percent 

Non-Fuel 

Compounds 

RHMW02 

and 

RHMW02D 

Average VPH 455

 

<30 Average EPH 545 1,375 27% 

1 RHMW02D is the field duplicate sample of RHMW02 

2

MADEP VPH – Massachusetts Department of Environmental Protection Volatile Petroleum 

Hydrocarbons (VPH) 

3

MADEP EPH – Massachusetts Department of Environmental Protection Extractable Petroleum 

Hydrocarbons (EPH) 

4

TPH-GRO – Total Petroleum Hydrocarbons, Gasoline Range Organics by USEPA Method 8015 Modified 

5

TPH-DRO – Total Petroleum Hydrocarbons, Diesel Range Organics by USEPA Method 8015 Modified 

6

Average Percent Non-Fuel Compounds computed by [1,375 – (455 + 545)/1,375] x 100 = 27% average 

percentage of Non-Fuel Compounds 

g/L – Micrograms per liter 

<30 – The compound was not detected, the value is the method detection limit 

Further evidence of interference from non-fuel hydrocarbons [i.e., tentatively identified 

compounds (TICs)] was found during Round 18 sampling conducted initially in January 2010, 

with resample events at RHMW02 for TPH-DRO only conducted in February and March 2010 

(Attachment D). 

The TPH-DRO chromatographs were reviewed and it was found that a significant fraction of the 

measured concentration was from TICs that were not associated with fuel hydrocarbons. Table 2 

indicates that on average, non-fuel related compounds accounted for approximately 35 percent of 

the total TPH-DRO concentrations. This data further supports the validity of the established 

SSRBL for TPH of 4,500 g/L. 

Table 2. Contribution of TICs to TPH-DRO Results 

Well Date 

TPH-DRO 

(g/L) 

TPH-DRO 

Corrected for 

TICs 

(g/L) 

Percent Non-Fuel 

Compounds 

RHMW02 1/26/2010 2,130 1,740 18.3% 

RHMW02D 1/26/2010 3,410 2,110 38.1% 

RHMW02 2/23/2010 8,650 3,470 59.9% 

RHMW02D 2/23/2010 6,910 2,930 57.6% 

RHMW02 3/30/2010 2,630 2,630 0.0% 

RHMW02D 3/30/2010 2,350 2,350 0.0% 

RHMW05 1/26/2010 2,060 541 73.7% 

Overall Total 

Average - - - 35% 
A related consideration pertains to the toxicity of the non-fuel organic compounds. The non-fuel 

hydrocarbon fraction of the TPH-DRO results that were captured by the silica gel column during 

the MADEP EPH analysis should be considered when evaluating relative toxicity. In a letter 

report to the Air Force by Zemo and Associates (2008) (Attachment E), it was estimated that the 

toxicity of the polar organics filtered out by the MADEP EPH analysis are approximately 24 

times less toxic than the most toxic fraction of the petroleum-related compounds. 

In summary, polar compounds that likely make up a significant fraction of the highest 

historically detected TPH-DRO concentrations at RHMW02 pose a much lower health risk than 

petroleum hydrocarbons being monitored from the Facility. In addition, these polar compounds 

and/or TICs provide an explanation as to why, absent detailed analysis, the calculated JP-5 

solubility SSRBL for TPH of 4,500 g/L seemed to have been exceeded during the Facility 

groundwater sampling Rounds 13 and 18 without the observation of free product in that 

monitoring well. Thus, the established SSRBL for TPH of 4,500 g/L still appears to be valid. 

Question 2 – Modeled GW Flow Direction & Question 3 – Validity of the Tier 3 Risk Assessment

As indicated in Attachment A, the revised groundwater flow direction and gradient validates and 

supports the existing Tier 3 Risk Assessment. This is because, with respect to the potential risk to 

the US Navy Well 2254-01, the results of the Tier 3 Risk Assessment are still valid since it 

assumes a worst case scenario that the dominant groundwater flow direction places the US Navy 

Well 2254-01 infiltration gallery directly down gradient from the USTs. 
Attachment C 

MADEP Letter Report 
1003 Bishop Street 

Pauahi Tower, Suite 1550 

Honolulu, HI 96813 

 (808) 528-1445 • fax (808) 528-0768 

www.tecinc.com 

March 26, 2010 

Greg Yamasaki, P.E. 

FISC Pearl Harbor, Code 701 

1942 Gaffney Street, Suite 100 

Building 1757, 2nd Floor 

Pearl Harbor, HI 96860-4549 

Subject: MADEP Risk Assessment Letter Report 

Red Hill, Pearl Harbor, HI 

Contract #N47408-04-D-8514, Task Order 54 

1.1 INTRODUCTION

This Letter Report was prepared for the Naval Fleet Engineering Service Center (NFESC) and 

the Pearl Harbor Naval Base Fleet Industrial Supply Center (FISC) by TEC Inc. (TEC) under 

contract N47408-04-D-8514, Task Order 0054. As part of Task Order 0054, TEC is providing 

environmental compliance services to FISC at the Red Hill Bulk Fuel Storage Facility (the 

Facility), associated with past releases of petroleum hydrocarbons to the subsurface bedrock and 

underlying groundwater aquifer. 

1.2 SITE DESCRIPTION

The Facility includes twenty - 12.5 million gallon (Mgal) underground storage tanks (USTs) 

located within the Red Hill Ridge, Halawa Valley, Hawaii. The Facility also includes a series of 

tunnels and pipelines which deliver fuel to and from Pearl Harbor Naval Base (Figure 1). The 

Facility was constructed prior to World War II to support naval activities in the Pacific. 

The USTs were constructed in the field using mining techniques, and are deferred from many 

Federal and State UST program requirements. According to records, the main fuel types stored 

at the Facility have been diesel oil, Navy Special Fuel Oil (NSFO), Navy Distillate (ND), Jet 

Propulsion Fuel 5 and 8 (JP-5 and JP-8), and F-76 (diesel marine fuel). In addition, Tank 17 

contained Aviation Gasoline (AVGAS) and Motor Gasoline (MOGAS) between 1964 and 1969; 

and Tank 18 contained AVGAS between 1964 and 1968. 

A review of the Facility records, which were classified until 1995, indicated that several USTs 

have been repaired over the years and may have released petroleum to the environment. This 

situation could potentially threaten drinking water aquifers. The Facility is approximately 100 

feet above the basal groundwater table on the boundary of the Waimalu and Moanalua Aquifer 

Systems of the Pearl Harbor and Honolulu Aquifer Sector, respectively. 

3 

Both aquifers are sources of potable water for several public water systems (Figure 2). Most 

notably, the U.S. Navy Well 2254-01, is located approximately 3,000 feet from Facility USTs 

and is permitted to pump approximately 4.6 million gallons per day (mgd) of potable water from 

a submerged infiltration tunnel. This tunnel extends approximately 1,280 feet across the water 

table and supplies the Pearl Harbor Water System. 

1.3 BACKGROUND

1.3.1 Summary of Previous Investigations 

In 2002, the U.S. Navy initiated a Site Investigation (SI), conducted by AMEC Earth and 

Environmental, Inc. (AMEC. 2002. Red Hill Bulk Fuel Storage Facility Investigation Report, 

Prepared for NAVFAC Pacific, August 2002) at the Facility. Rock core samples were collected 

from directly beneath the Facility USTs and groundwater samples were collected from a single 

well installed within the lower access tunnel. Results indicated that petroleum had been released 

from Facility USTs, as observed in core samples, and in groundwater samples. After evaluating 

the results of the SI, the State of Hawaii, Department of Health (HDOH), Solid and Hazardous 

Waste Branch (SHWB) requested that quarterly groundwater monitoring commence, a Tier 3 

risk assessment be conducted to evaluate the risk to the U.S. Navy pumping well at Red Hill, and 

a contingency plan be developed to ensure the protection of the U.S. Navy pumping well at Red 

Hill from future contamination. 

The U.S. Navy initiated quarterly groundwater sampling at the existing monitoring well 

(formerly MW1, currently RHMW01) and at the U.S. Navy well 2254-01. Dawson Group, Inc. 

(Dawson Group, Inc. 2006. Fourth Quarter 2005 Groundwater Sampling Report, Red Hill Fuel 

Storage Facility, Hawaii. February 2006) conducted the first four sampling events in February 

2005, June 2005, September 2005, and December 2005 (Rounds 1 through 4). 

1.3.1.1 TEC Inc. Site Investigation and Risk Assessment (2004 to 2006) 

In 2004, TEC was tasked to conduct a SI, Risk Assessment, and produce a contingency plan in 

the event that contamination from the Facility required closure of nearby drinking water wells. 

As part of this site investigation, groundwater monitoring well RHMW02 was installed directly 

upgradient from Tanks 5 and 6, and groundwater monitoring well RHMW03 was installed 

directly upgradient of Tanks 13 and 14. RHMW04 was installed in a location assumed to be 

upgradient of the tanks to measure background concentrations of contamination to ensure an 

offsite plume is not contributing to the contamination detected at the Facility. In addition, 

groundwater monitoring well RHMW2254-01 was installed within the U.S. Navy Well 2254-01 

infiltration gallery. 

The purpose of installing these additional wells was to divide the Facility into three groundwater 

sections so that inadvertent fuel releases from each section could be detected by the associated 

well. Two additional rounds of groundwater samples (Round 5 and 6) were collected and 

analyzed for risk assessment purposes. Groundwater samples were analyzed for Volatile 

Organic Compounds (VOCs) by United State Environmental Protection Agency (USEPA) 

Method SW 8260B, Total Petroleum Hydrocarbons quantified as Gasoline Range Organics 

(TPH-GRO) and Diesel Range Organics (TPH-DRO) by USEPA Method SW8015B, SemiVolatile Organic Compounds (SVOCs) by USEPA Method SW8270C, and lead by USEPA 

Method SW6010B. Samples were validated for decision making and risk assessment.
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Moanalua Fwy

Halawa Shaft

(2354-01)

Halawa Stream

North Halawa Stream

Moanalua Stream

South Halawa Stream

South Halawa Stream

2255-392255-372255-38

2253-03

2253-01

2253-02

2154-01 2153-09

2155-04

2254-02

Halawa Red Hill

(2254-01)

Moanalua Monitor

(2153-05)

2153-10

2153-04

2153-11

2153-072153-08

2153-12

Printing Date: Apr. 23, 2007, File: I:\Projects\Red Hill\Figures\Draft Technical Report\Figure 1-8_Area Wells and Aquifer Systems.mxd

30201111

(11111)

30201116

(12212)

30104116

(11113)

30104111

(11111)

Figure 

2

Area Wells and Aquifer SystemsRed Hill Fuel Storage FacilityOahu, Hawaii
5 

In 2006, TEC conducted a Tier 1, Tier 2, and Tier 3 Human Health Risk Assessment for the 

Facility using the results from the SI described above (TEC, 2007. Red Hill Bulk Fuel Storage 

Facility, Final Technical Report, Pearl Harbor, Hawaii. August 2007). The Tier 1 risk 

screening assessment was conducted for groundwater to determine compounds of potential 

concern (COPCs). 

The Tier 1 risk assessment determined that groundwater beneath the Facility did not meet 

standards for residential potable water use and that naphthalene, TPH-GRO, tetrachloroethylene, 

1,2,-dichloroethylene, trichloroethyelene, and lead should be evaluated further as COPCs. 

A Tier 2 Risk Assessment was conducted to evaluate migration pathways for contaminants. It 

was determined that there was no potential seepage of leachate or product to the ground surface 

or surface water in the vicinity of the Facility because the underlying water table is between 80 

and 220 feet below the surrounding valley floors. The risk assessment also concluded that the 

soil vapor migration pathway was not a significant concern. Finally, it was determined that since 

groundwater is not used directly beneath the Facility; there were no current risks associated with 

hydrocarbon concentrations detected in monitoring wells located within the Facility. 

Several potable water production wells are located within a 1.5 mile radius from the Facility. 

The Honolulu Board of Water Supply (HBWS) Halawa Shaft (2354-01) is approximately 5,000 

feet to the northwest of the Facility. HBWS Moanalua Wells (2153-10, -11 and -12) are located 

approximately 8,500 feet south of the Facility. The U. S. Navy drinking water well 2254-01 is 

located approximately 4,000 feet to the west of the Facility. Groundwater sample results from 

RHMW 2254-01 indicated that this pathway was not complete at that time. 

In order to evaluate the potential for these groundwater supply wells to be contaminated in the 

future from leaking USTs at the Facility, TEC conducted a Tier 3 assessment of future risk to 

these potable water production wells. A site-specific conceptual model was used that considered 

particle mass degradation of hydrocarbon compounds in both oxygenated and anaerobic 

groundwater. TEC used the Reactive Multispecies Transport in 3-Dimensions (RT3D) to model 

solute (i.e., dissolved contaminant) transport and natural attenuation of hydrocarbons utilizing 

the groundwater flow solution produced by the MODFlow modeling code. 

RT3D models the natural attenuation of hydrocarbons using the stochiometry of the chemical 

reactions and estimated kinetic constants that govern the rate at which these chemical reactions 

occur. The model inputs were based on experimental or empirically defined values for 

chemicals of concern (COCs). Based on screening assessments of transport properties, worst 

case initial concentrations, and chemical toxicities or action levels, TEC determined that for the 

fuel currently stored at the Facility, benzene and TPH (i.e., TPH-DRO and TPH-GRO) were the 

pertinent COCs because these would be observed first in the U.S. Navy Well 2254-01 at levels of 

concern. 

The results of the Tier 3 Risk Assessment indicated that fuel product must be present on the 

groundwater in a plume extending to within approximately 1,100 feet of the U.S. Navy Well 

2254-01 infiltration gallery in order for dissolved contaminants in groundwater to present a 

potentially unacceptable risk to the Pearl Harbor Water System. The model indicated that TPH 

would be the first COC to reach unacceptable concentrations in this scenario. 

Action levels in groundwater from monitoring wells within the Facility were set at the solubility 

limit of TPH and benzene (assuming that JP-5 was the fuel released), as a way of estimating 
6 

whether fuel was present on the water table nearby. JP-5 COC Action Levels from this study are 

contained in the Facility’s Groundwater Protection Plan (TEC, 2008. Red Hill Bulk Fuel 

Storage Facility, Final Groundwater Protection Plan, Pearl Harbor, Hawaii. January 2008) as 

site-specific risk based levels (SSRBLs) and presented below. These site-specific Action Levels 

or SSRBLs were based upon the assumption that fuel (i.e., free product) would be present on 

groundwater at Facility monitoring wells: 

 The site-specific Action Level (solubility limit) for TPH resulting from a JP-5 release 

was 4.5 milligrams per liter (mg/L); and 

 The site-specific Action Level (solubility limit) for benzene resulting from a JP-5 release 

was 0.75 mg/L. 

1.3.1.2 TEC Inc. Long-Term Groundwater Monitoring (2006-2009) 

Based on release response requirements from HDOH, the U.S. Navy has conducted quarterly 

groundwater monitoring events following the SI (TEC, 2007. Red Hill Bulk Fuel Storage 

Facility, Final Technical Report, Pearl Harbor, Hawaii. August 2007). A total of 16 Rounds of 

groundwater monitoring have been conducted through July 2009. Prior to Round 16, samples 

were analyzed for TPH-DRO and TPH-GRO by USEPA Method 8015, VOCs by USEPA 

Method 8260, Polynuclear Aromatic Hydrocarbons (PAHs) by USEPA Method 8270C SIM, and 

dissolved lead by USEPA Method 8020. Results from these rounds have indicated TPH-DRO is 

consistently present in RHMW02 and RHMW01. In Round 13, TPH-DRO exceeded the 

Groundwater Protection Plan Category 4 Action Level, which required the U.S. Navy to evaluate 

concentrations in surrounding wells, and install an additional monitoring well (RHMW05) 

between the Facility and the U.S. Navy Well 2254-01. 

In Round 16 (July 2009), the U.S. Navy included fractionation analyses for TPH by the protocol 

developed by Massachusetts Department of Environmental Protection (MADEP), Characterizing 

Risks Posed by Petroleum Contaminated Sites: Implementation of the MADEP VPH/EPH 

Approach, Policy #WSC-02-411 (MADEP, 2002), to better understand the chemistry of the TPH 

plume under the Facility, and to re-assess the risk associated with these plumes. 

Additional TPH fractions can be evaluated for risk because MADEP has determined toxicity 

reference doses (RfDs) for these specific fractions that make up the TPH-gasolines and TPHmiddle distillate ranges (including diesel). For Round 16, MADEP fractions for Volatile 

Petroleum Hydrocarbons (VPH) and Extractable Petroleum Hydrocarbons (EPH) were measured 

along with TPH-GRO and TPH-DRO in split samples from RHMW01, RHMW02, and 

RHMW03. 
7 

 The results are provided for comparison in Table 1 below. 

Table 1. Total Petroleum Concentrations, MADEP Compared to USEPA Method 8015 

Monitor Well 

ID 

MADEP VPH 

(g/L) 

TPH-GRO 

(g/L) 

MADEP EPH 

(g/L) 

TPH-DRO 

(g/L) 

RHMW01 Total VPH <100 

C5-C8 Aliphatics <100 

C9-C10 Aromatics <100 

C9-C12 Aliphatics <100 

<30 Total EPH <100 

C11-C22 Aromatics <100 

C19-C36 Aliphatics <100 

C9-C18 Aliphatics <100 

248 

RHMW02 Total VPH 420 

C5-C8 Aliphatics <100 

C9-C10 Aromatics 420 

C9-C12 Aliphatics <100 

<30 Total EPH 540 

C11-C22 Aromatics 270 

C19-C36 Aliphatics <100 

C9-C18 Aliphatics 270 

1,450 

RHMW02D1 Total VPH 490 

C5-C8 Aliphatics <100 

C9-C10 Aromatics 490 

C9-C12 Aliphatics <100 

<30 Total EPH 550 

C11-C12 Aromatics 280 

C19-C36 Aliphatics <100 

C9-C18 Aliphatics 270 

1,300 

RHMW03 Total VPH <100 

C5-C8 Aliphatics <100 

C9-C10 Aromatics <100 

C9-C12 Aliphatics <100 

<30 Total EPH <100 

C11-C22 Aromatics <100 

C19-C36 Aliphatics <100 

C9-C18 Aliphatics <100 

<150 

1 RHMW02D is the field duplicate sample of RHMW02 

MADEP VPH – Massachusetts Department of Environmental Protection Volatile Petroleum Hydrocarbons (VPH) 

MADEP EPH – Massachusetts Department of Environmental Protection Extractable Petroleum Hydrocarbons 

(EPH) 

TPH-GRO – Total Petroleum Hydrocarbons, Gasoline Range Organics by USEPA Method 8015 Modified 

TPH-DRO – Total Petroleum Hydrocarbons, Diesel Range Organics by USEPA Method 8015 Modified 

g/L – Micrograms per liter 

<100 – The compound was not detected, the value is the method detection limit 

1.3.2 MADEP EPH/VPH versus USEPA Method 8015 Modified TPH-DRO/GRO 

In order to estimate risk associated with TPH as a mixture, MADEP derived toxicity-based 

reference doses for specific fractions of EPH and VPH. In addition, MADEP developed specific 

testing methodologies to ensure that they were measuring the correct fraction and not other 

components of the mixture that were not petroleum hydrocarbons. In the development of EALs 

for petroleum mixtures in groundwater, HDOH used toxicity factors developed by MADEP as an 

approximation of toxicity factors for more widely available EPA Method 8015 Modified (TPHDRO and TPH-GRO) (HDOH, 2005). Attachment 1 provides additional discussion regarding 

MADEP vs. Method 8015 analytical methods. 

In general, MADEP VPH analytical results should approximate TPH-GRO analysis results, and 

MADEP EPH analytical results should approximate TPH-DRO analysis results. However, there 

are several variations in the methods that can account for observed differences in concentrations 

associated with these analytical methods as described below: 

EPH vs. TPH-DRO: 

1. EPH Method measures extractable hydrocarbons from C9 to C36, but does not include 17 

PAHs. TPH-DRO includes the 17 PAH and is generally limited to C9 through C26 

extractable hydrocarbons. 

2. The EPH Method includes a silica gel cleanup to remove biogenic interferences that can 

cause high biases or “false positives”. This clean-up process removes polar compound 
8 

interferences such as breakdown products (e.g., oils, sugars, and fatty acids) from the 

extract without affecting the non-polar petroleum hydrocarbons. This silica gel cleanup 

is used because older fuel releases degrade over time and the resulting non-hydrocarbon 

breakdown products are significantly less toxic than the parent hydrocarbons. Because 

the TPH-DRO analytical method does not include the silica gel cleanup process, TPHDRO analytical results may include these polar compounds breakdown products that are 

not extractable petroleum hydrocarbons. The inclusion of these breakdown products 

tends to bias the TPH-DRO method results higher than EPH method results. 

3. Differing calibration standards between laboratories. 

4. Variability associated with split samples. 

 VPH vs. TPH-GRO 

1. Differences in the VPH and TPH-GRO analytical results may be associated with 

differences in the carbon range for the different analyses (e.g., since TPH-DRO analyses 

overlaps the VPH analyses with respect to the carbon range, this can result in VPH 

detectable results being expressed as TPH-DRO, not TPH-GRO; see Table 1, RHMW02 

and RHMW02D results). In addition, VPH measures the volatile hydrocarbons from C5 

to C12, but does not include BTEX, MtBE, or naphthalene. TPH-GRO results includes 

BTEX, MtBE, and naphthalene. 

2. Differing calibration standards between laboratories. 

3. Variability associated with split samples. 

In summary, the lack of silica gel cleanup or similar removal of polar compounds may cause the 

TPH-DRO analytical method to report results that are significantly greater than what would be 

reported as part of the EPH analytical method under certain circumstances. 

Table 2 provides values of physical and chemical properties for MADEP fractions. 

Table 2. Recommended VPH/EPH Fractional Properties for Modeling Purposes 

MADEP 

Petroleum 

Fractions 

Equivalent 

Carbon 

Number 

(EC) 

Molecular 

Weight 

Vapor 

Pressure 

(atms) 

Solubility 

in Water 

(g/L) 

 Henry’s 

Constant, H 

(dimension 

- less) 

Partition 

Coeff, 

Koc 

(mL/g) 

Diffusion 

Coeff 

(cm2

/s) 

air w ater 

C5-C8 Aliphatics 6.5 93 0.10 11,000 54 2265 0.08 1 x 10-5

C9-C12 

Aliphatics 

10.5 149 8.7 x 10-4 70 65 1.5 x 105 0.07 1 x 10-5

C9-C10 

Aromatics 

9.5 120 2.9 x 10-3 51,000 0.33 1778 0.07 1 x 10-5

C9-C18 

Aliphatics 

12 170 1.4 x 10-4 10 69 6.8 x 105 0.07 5 x 10-6

C19-C36 

Aliphatics 

considered immobile 

C11-C22 

Aromatics 

14 150 3.2 x 10-5 5800 0.03 5000 0.06 1 x 10-5
9 

1.4 HDOH REGULATORY UPDATES AND ASSOCIATED STUDIES 

Information obtained from recent U.S. Air Force environmental investigations in Hawaii indicate 

favorable results when using TPH fractionation methods, such as those presented by MADEP 

(MADEP, 2002) while conducting quantitative risk assessments for TPH in groundwater that is 

drinking water. At these sites, when comparing TPH-DRO and EPH groundwater split sample 

data, TPH-DRO results tend to be higher than the EPH results. This data indicates that the TPHDRO analytical method may be over estimating the associated site risk for older release sites 

where the hydrocarbons have been degraded in the groundwater. As mentioned above, this can 

occur because with EPH analyses, the polar, non-hydrocarbon degradation products are filtered 

out with silica gel, whereas with the TPH-DRO analyses, these non-hydrocarbon significantly 

less toxic breakdown products are not removed prior to the analysis. 

 Prior to 2005, HDOH did not consider TPH toxicity in risk based groundwater studies, rather 

concentrations of TPH were considered only in cases of gross contamination and concentrations 

of TPH constituents (e.g., benzene, toluene, ethylbenzene, xylenes and/or naphthalene 

[BTEXN]), were evaluated for risk. Hawaii Administrative Rules (HAR) Chapter 11-281, 

Subchapter 7, Release Response Action presented Table 1-1a and 1-1b, Tier 1 Action Levels for 

Soil and Groundwater with “NS” (No Standard) for TPH-residual fuels (oil and grease), TPH 

middle distillates (diesel and kerosene), and TPH-gasolines for groundwater where drinking 

water is threatened. 

In May 2005, HDOH published Screening For Environmental Concerns At Sites With 

Contaminated Soil and Groundwater, (HDOH, 2005), which included Environmental Action 

Levels (EALs) for TPH-middle distillates (including diesel) and TPH-gasolines in groundwater 

used for drinking based on the nuisance taste and odor. These levels were set at 100 microgram 

per liter (g/L), for each, with non-drinking water EALs set at 2,000 g/L for TPH-gasolines and 

5,000 g/L for TPH-middle distillates (including diesel). These values were still not risk-based, 

and could not be used to quantify risk. 

In 2008, HDOH updated their EALs for TPH-middle distillates and TPH-gasolines in Evaluation 

of Environmental Hazards at Sites with Contaminated Soil and Groundwater (HDOH, 2008). 

This document was based on studies conducted by the Massachusetts Department of 

Environmental Protection (MADEP, 2002). HDOH risk-based EALs for TPH for groundwater 

that is drinking water were revised to 100 g/L for TPH-gasolines and 210 g/L for TPH-middle 

distillates (including diesel). 

In setting these EALs, HDOH generally assumed that the components of each TPH mixture 

consisted of the most toxic fractions. However, measuring the amount of each fraction using the 

MADEP method allows a more precise determination of risk that does not assume the highest 

chemical toxicity by default. For example, in Table 1 monitoring well RHMW02 had an EPH 

that consisted of roughly equal amounts of C11-C22 aromatics and C9-C18 aliphatics. The C9-

C18 aliphatic fraction has oral and inhalation toxicities, as measured by a reference dose (RfD; a 

factor that can be interpreted as a “safe” dose) over three times higher than the C11-C22 

aromatic fraction. Thus, a lower risk is determined for this sample. 

There is considerable evidence that the TPH-DRO analytical method provides results that are 

biased high, particularly when measuring older fuel releases. As mentioned above, older fuel 

releases degrade, and the resulting non-hydrocarbon breakdown products are significantly less 

toxic than the parent hydrocarbons. However, as previously discussed, MADEP EPH analytical 
10 

methodologies for TPH-middle distillates (including diesel) include a silica gel filtration process 

that removes non-hydrocarbon components, while the TPH-DRO method does not. 

In a recent environmental investigation conducted for the U.S. Air Force (TEC 2008. 

Supplemental Remedial Investigation Report at ST18, Hickam POL Site, Oahu, Hawaii July 

2008), aviation gasoline (AVGAS) was released from the Hickam Air Force Base Petroleum, 

Oils and Lubricants (POL) pipelines that have been inactive since the mid 1950’s. Analytical 

results from TPH-DRO and TPH-GRO analysis (Method 8015) indicated that a large TPHmiddle distillate plume was present, where a TPH-gasoline plume was expected. To resolve this 

issue, the U.S. Air Force compared TPH-DRO and MADEP EPH results in ten affected wells 

during two semi-annual rounds of sample collection at the site (i.e., Rounds 3 and 4) to assess 

fractional toxicity differences, as well as to better understand the potential high bias for the 

middle distillate results from the TPH-DRO analyses. In Round 3, MADEP EPH concentrations 

were approximately half the TPH-DRO concentrations in the six wells in which both were 

detected. This indicated that approximately half the TPH-DRO component was not from 

hydrocarbons, but most likely less toxic breakdown products from the degraded fuel. Similar 

results were obtained from the Round 4 comparison. 

This may have significance at the Facility, since fuel releases are expected to have occurred in 

the past, which may result in a significant amount of the compounds found in the TPH-DRO 

analysis being less toxic breakdown products. Conversely, if a recent release was sampled, it 

would be expected that the TPH-DRO and EPH concentrations would approximate each other, 

since no non-hydrocarbon breakdown products would be present to bias the TPH-DRO result 

toward higher concentrations. 

1.5 RISK ANALYSIS AT THE FACILITY USING MADEP FRACTIONATION METHODS

For the purposes of this Letter Report, a Tier 1 Human Health Risk Screening Assessment is 

conducted below, based on the conservative assumption that the groundwater beneath the 

Facility is potable water used by residents. Table 3 and Table 4 indicate that for Round 16 

groundwater sampling only TPH-gasolines and TPH-middle distillates (including diesel) are 

COPCs. All others are not detected or detected at less than the HDOH EAL screening criteria. 

All COPCs detected in groundwater underlying the Facility are non-carcinogens. Noncarcinogenic risk is determined through the calculation of a ratio, the hazard quotient (HQ), 

which is the ratio of intake to an RfD (i.e., an intake without an appreciable risk of deleterious 

effects during a lifetime). The simplified formula to calculate an HQ is: 

HQ = CDI/RfD where: 

HQ = Hazard quotient; 

CDI = Calculated average daily intake of COPC (mg/kg-day); and 

RfD = Reference dose (mg/kg-day). 

The CDI for potable water exposure is calculated using measured concentrations and the EPA 

Region IX default exposure assumptions and the formula for establishing PRGs (USEPA, 2004). 

It includes oral intake and inhalation during water use such as showering. 

USEPA generally considers an HQ of 1.0 or less to be acceptable. EALs and PRGs can be 

developed for non-carcinogens by selecting an HQ of 1.0 and then back-calculating an 
Table 3. Analytical Results for MADEP Sampling Report (Round 16, July 15, 2009), Red Hill Fuel Storage Facility Pearl Harbor Hawaii

Result Q MDL RL Result Q MDL RL Result Q MDL RL 

TPH as DIESEL RANGE ORGANICS 210 100 248 F 161 430 1450 150 400 1300 150 400 

TPH as GASOLINE RANGE ORGANICS 100 100 ND U 30 100 ND U 30 100 ND U 30 100 1-METHYLNAPHTHALENE 4.7 10 9.44 0.158 0.526 13.2 0.156 0.521 10.6 0.165 0.549 

2-METHYLNAPHTHALENE 24 10 3.07 0.158 0.526 3.66 0.156 0.521 2.58 0.0165 0.0549 ACENAPHTHENE 370 20 0.18 0.0158 0.0526 0.235 0.0156 0.0521 0.213 0.0165 0.0549 ACENAPHTHYLENE 240 2000 ND U 0.0158 0.0526 ND U 0.0156 0.0521 ND U 0.0165 0.0549 ANTHRACENE 1800 22 ND U 0.0158 0.0526 ND U 0.0156 0.0521 ND U 0.0165 0.0549 BENZO(a)ANTHRACENE 0.092 4.7 ND U 0.0158 0.0526 ND U 0.0156 0.0521 ND U 0.0165 0.0549 BENZO(a)PYRENE 0.2 0.81 ND U 0.0158 0.0526 ND U 0.0156 0.0521 ND U 0.0165 0.0549 BENZO(b)FLUORANTHENE 0.092 0.75 ND U 0.0158 0.0526 ND U 0.0156 0.0521 ND U 0.0165 0.0549 BENZO(g,h,i)PERYLENE 1500 0.13 ND U 0.0158 0.0526 ND U 0.0156 0.0521 ND U 0.0165 0.0549 BENZO(k)FLUORANTHENE 0.92 0.4 ND U 0.0158 0.0526 ND U 0.0156 0.0521 ND U 0.0165 0.0549 CHRYSENE 9.2 1 0.0159 F 0.0158 0.0526 0.0162 F 0.0156 0.0521 ND U 0.0165 0.0549 DIBENZ(a,h)ANTHRACENE 0.0092 0.52 ND U 0.0158 0.0526 ND U 0.0156 0.0521 ND U 0.0165 0.0549 FLUORANTHENE 1500 130 0.0263 F 0.0158 0.0526 0.0247 F 0.0156 0.0521 0.0199 F 0.0165 0.0549 FLUORENE 240 950 0.0952 0.0158 0.0526 0.115 0.0156 0.0521 0.108 0.0165 0.0549 INDENO(1,2,3-c,d)PYRENE 0.092 0.095 ND U 0.0158 0.0526 ND U 0.0156 0.0521 ND U 0.0165 0.0549 NAPHTHALENE 17 21 5.61 0.326 1.05 8.37 0.323 1.04 6.71 0.341 1.1 PHENANTHRENE 240 410 0.0349 F 0.0158 0.0526 0.0304 F 0.0156 0.0521 0.0291 F 0.0165 0.0549 PYRENE 180 68 0.027 F 0.0158 0.0526 0.0272 F 0.0156 0.0521 0.0189 F 0.0165 0.0549 1,1,1,2-TETRACHLOROETHANE 0.52 50000 ND U 0.15 0.5 ND U 0.15 0.5 ND U 0.15 0.5 1,1,1-TRICHLOROETHANE 200 970 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 1,1,2,2-TETRACHLOROETHANE 0.067 500 ND U 0.15 0.5 ND U 0.15 0.5 ND U 0.15 0.5 1,1,2-TRICHLOROETHANE 5 50000 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 1,1-DICHLOROETHANE 2.4 50000 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 1,2,3-TRICHLOROPROPANE (TCP) 0.6 50000 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 1,2,4-TRICHLOROBENZENE 70 3000 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 1,2-DIBROMO-3-CHLOROPROPANE (DBCP) 0.04 10 ND U 0.62 2 ND U 0.62 2 ND U 0.62 2 1,2-DIBROMOETHANE (EDB) 0.0065 50000 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 1,2-DICHLOROBENZENE 600 10 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 1,2-DICHLOROETHANE 0.15 7000 ND U 0.15 0.5 ND U 0.15 0.5 ND U 0.15 0.5 1,2-DICHLOROPROPANE 5 10 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 1,3-DICHLOROBENZENE 180 50000 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 1,4-DICHLOROBENZENE 75 5 ND U 0.15 0.5 ND U 0.15 0.5 ND U 0.15 0.5 ACETONE 22000 20000 ND U 3.1 10 ND U 3.1 10 ND U 3.1 10 BENZENE 5 170 ND U 0.12 0.4 ND U 0.12 0.4 ND U 0.12 0.4 BROMODICHLOROMETHANE 0.22 50000 ND U 0.15 0.5 ND U 0.15 0.5 ND U 0.15 0.5 BROMOFORM 100 510 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 BROMOMETHANE 8.7 50000 ND U 0.94 3 ND U 0.94 3 ND U 0.94 3 CARBON TETRACHLORIDE 5 520 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 CHLOROBENZENE 100 50 ND U 0.15 0.5 ND U 0.15 0.5 ND U 0.15 0.5 CHLOROETHANE 8600 16 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 CHLOROFORM 70 2400 ND U 0.3 1 ND U 0.3 1 ND U 0.3 1 CHLOROMETHANE 1.8 50000 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 

cis-1,2-DICHLOROETHYLENE 70 50000 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 cis-1,3-DICHLOROPROPENE 0.43 50000 ND U 0.15 0.5 ND U 0.15 0.5 ND U 0.15 0.5 DIBROMOCHLOROMETHANE 0.16 50000 ND U 0.15 0.5 ND U 0.15 0.5 ND U 0.15 0.5 ETHYLBENZENE 700 30 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 HEXACHLOROBUTADIENE 0.86 6 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 

M,P-XYLENE (SUM OF ISOMERS) 10000 20 ND U 0.62 2 ND U 0.62 2 ND U 0.62 2 

METHYL ETHYL KETONE (2-BUTANONE) 7100 8400 ND U 3.1 10 ND U 3.1 10 ND U 3.1 10 METHYL ISOBUTYL KETONE (4-METHYL-2-PENTANONE) 2000 1300 ND U 3.1 10 ND U 3.1 10 ND U 3.1 10 METHYLENE CHLORIDE 4.8 9100 ND U 1 5 ND U 1 5 ND U 1 5 

NAPHTHALENE 17 21 ND U 0.62 2 10.1 0.62 2 11.2 0.62 2 

STYRENE 100 10 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 TETRACHLOROETHYLENE(PCE) 5 170 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 TOLUENE 1000 40 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 

trans-1,2-DICHLOROETHENE 100 260 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 TRICHLOROETHYLENE (TCE) 5 310 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 

VINYL CHLORIDE 2 3400 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 

6020 LEAD 15 50000 ND U 0.31 1 ND U 0.31 1 ND U 0.31 1 

PAHs - Polynuclear aromatic hydrocarbons MDL - Method detection limit

VOCs - Volatile organic compounds RL - Reporting limit

UG/L - Micrograms per Liter TPH - Total petroleum hydrocarbons 

Q - Data qualifier ND - Indicates that the compound was not detected above the stated method de

U - Indicates that the compound was analyzed for but not detected at or above the stated limit

F - Indicates that the compound was identified but the concentration was above the MDL and below the RL

- Result exceeds one or both HDOH EALs

12

Method

HDOH Drinking Water 

EALs1

for Human Toxicity 

UG/L

8260B 

(VOCs)

RHMW02D 

UG/L

8015B (Petroleum)

8270C SIM 

(PAHs)

RHMW02 

HDOH Groundwater 

Gross Contamination 

EALs2

UG/L

Chemical

RHMW01

UG/L UG/L

Final Drinking Water Action Levels for Human Toxicity, Table D-3a, Screening for Environmental Concerns at Sites with Contaminated Soil and Groundwater, HDOH, 2009Groundwater Gross Contamination Action Levels, Table G-1, Screening for Environmental Concerns at Sites with Contaminated Soil and Groundwater, HDOH, 2009

July 15, 2009 July 15, 2009 July 15, 2009 

200

Page 1 of 1
Table 4. MADEP Analytical Results for MADEP Sampling Report (Round 16, July 15, 2009), Red Hill Fuel Storage Facility, Pearl Harbor, Hawaii

Result Q MDL RL Result Q MDL RL Result 

MADEP 

EPH EXTRACTABLE PETROLEUM HYDROCARBONS C11-C22 AROMATIC ND U 100 100 270 100 100 280 

EXTRACTABLE PETROLEUM HYDROCARBONS C19-C36 ALIPHATIC ND U 100 100 ND U 100 100 ND EXTRACTABLE PETROLEUM HYDROCARBONS C9-C18 ALIPHATIC ND U 100 100 270 100 100 270 

TOTAL EXTRACTABLE PETROLEUM HYDROCARBONS ND U 100 100 540 100 100 550 

MADEP 

PAHs 2-METHYLNAPHTHALENE 24 10 ND U 10 10 ND U 10 10 ND 

ACENAPHTHENE 370 20 ND U 10 10 ND U 10 10 ND ACENAPHTHYLENE 240 2000 ND U 10 10 ND U 10 10 ND ANTHRACENE 1800 22 ND U 10 10 ND U 10 10 ND BENZO(a)ANTHRACENE 0.092 4.7 ND U 10 10 ND U 10 10 ND BENZO(a)PYRENE 0.2 0.81 ND U 10 10 ND U 10 10 ND BENZO(b)FLUORANTHENE 0.092 0.75 ND U 10 10 ND U 10 10 ND BENZO(g,h,i)PERYLENE 1500 0.13 ND U 10 10 ND U 10 10 ND BENZO(k)FLUORANTHENE 0.92 0.4 ND U 10 10 ND U 10 10 ND CHRYSENE 9.2 1 ND U 10 10 ND U 10 10 ND FLUORANTHENE 1500 130 ND U 10 10 ND U 10 10 ND FLUORENE 240 950 ND U 10 10 ND U 10 10 ND INDENO(1,2,3-cd)PYRENE+DIBENZ(a,h)ANTHRACENE ND U 10 10 ND U 10 10 ND NAPHTHALENE 17 21 ND U 10 10 ND U 10 10 ND PHENANTHRENE 240 410 ND U 10 10 ND U 10 10 ND PYRENE 180 68 ND U 10 10 ND U 10 10 ND 

MADEP 

VPH VOLATILE PETROLEUM HYDROCARBONS C5-C8 ALIPHATIC ND U 100 100 ND U 100 100 ND 

VOLATILE PETROLEUM HYDROCARBONS C9-C10 AROMATIC ND U 100 100 420 100 100 490 

VOLATILE PETROLEUM HYDROCARBONS C9-C12 ALIPHATIC ND U 100 100 ND U 100 100 ND 

TOTAL VOLATILE PETROLEUM HYDROCARBONS ND U 100 100 420 100 100 490 

MADEP 

BTEX-M BENZENE 5 170 ND U 5 5 ND U 5 5 ND 

ETHYLBENZENE 700 30 ND U 5 5 ND U 5 5 ND M,P-XYLENE (SUM OF ISOMERS) 10000 20 ND U 10 10 ND U 10 10 ND NAPHTHALENE 17 21 ND U 10 10 ND U 10 10 ND O-XYLENE (1,2-DIMETHYLBENZENE) ND U 5 5 ND U 5 5 ND tert-BUTYL METHYL ETHER ND U 5 5 ND U 5 5 ND TOLUENE 1000 40 ND U 5 5 ND U 5 5 ND 

MADEP 

EPH - Massachusetts Department of Environmental Protection Extractable Petroleum Hydrocarbons MDL - Method detection limit

MADEP 

VPH - Massachusetts Department of Environmental Protection Volatile Petroleum Hydrocarbons RL - Reporting limit

UG/L - Micrograms per Liter ND -

Q - Data qualifier

U - Indicates that the compound was analyzed for but not detected at or above the stated limit

- Result exceeds the laboratory method detection limit

12

Jul

Groundwater Gross Contamination Action Levels, Table G-1, Screening for Environmental Concerns at Sites with Contaminated Soil and Groundwater, HDOH, 2009Final Drinking Water Action Levels for Human Toxicity, Table D-3a, Screening for Environmental Concerns at Sites with Contaminated Soil and Groundwater, HDOH, 2009

Indicates that the compound wamethod detection limit

RH

Method

HDOH Drinking 

Water EALs1

for Human Toxicity 

UG/L

HDOH Groundwater 

Gross Contamination 

EALs2

UG/L

Chemical

RHMW01

UG/L

July 15, 2009 July 15, 2009

RHMW02

UG/L

200

Page 1 of 1
13 

acceptable concentration using standard exposure parameters. For multiple chemicals or 

fractions at an exposure point (e.g. for a monitoring well) a Hazard Index (HI) is calculated by 

summing the HQs. 

1.5.1.1 Direct Exposure Risk Results 

For purposes of this risk assessment, the MADEP results from Round 16 are used for the 

definitive evaluation of risk because it is assumed that greater accuracy is achieved when 

evaluating more specific components of petroleum, versus the broad categories of TPH-GRO 

and TPH-DRO. 

MADEP fractions were only observed above the detection limit at RHMW02, in both the normal 

and duplicate sample (Table 1). Direct exposure risk calculations and for this sample are shown 

in Table 5. For the potential future residential scenario of groundwater use as potable water, 

MADEP VPH and MADEP EPH exceeded an HQ of 1.0 for monitoring well RHMW02, thus 

indicating a potential non-carcinogenic risk. 

 The HQ at RHMW02 for MADEP VPH ranged between 4.4 and 5.1 based entirely on 

C9-C10 Aromatics detected in the normal (420 g/L) and duplicate (490 g/L) sample. 

 The HQ at RHMW02 for MADEP EPH was 3.5, based on C9-C18 Aliphatics Aromatics 

detected in the normal (270 g/L) and duplicate (270 g/L) sample, and C11-C22 

Aromatics (270 g/L in the normal and 280 g/L in the duplicate samples). 

 The total HI for these samples ranged from 8.0 for the normal sample to 8.7 for the 

duplicate sample. 

Although an HI of 8.0 to 8.7 represents a potentially unacceptable risk if observed in the Pearl 

Harbor Water System, it represents actual risk only if these same concentrations were to migrate 

to the U.S. Navy Well 2254-01, or if potable water wells were installed within the maximum 

concentrations associated with the plume. In the July 2009 Round 16 sampling event, MADEP 

fractions were not detected in the sample from RHMW01 (located between RHMW02 and the 

U.S. Navy Well 2254-01). MADEP analyses were not conducted at RHMW05 (between 

RHMW01 and U.S. Navy Well 2254-01) or at RHMW2254-01 (located within the U.S. Navy 

Well 2254-01 infiltration gallery)
14 

Table 5. Risk Estimates for Groundwater, RHMW02 Round 16 

Risk Calculation Equation* 

TC = THQ x BWa x ATn x 1000 ug/ mg 

 EFr x EDr [(IRWa/RfDo) + (VFw x IRAa/RfDi)] 

VPH EPH 

Risk Parameter Identification C5-C8 C9-C12 C9-C10 C9-C18 C19-C36 C11-C22 

Aliphatics Aliphatics Aromatics Aliphatics Aliphatics Aromatics 

THQ =Target Hazard Quotient 1 1 1 1 1 1Bwa = Adult Body Weight (kg) 70 70 70 70 70 70Atn = Averaging Time (d) 10950 10950 10950 10950 10950 10950Efr = Exposure Frequency (d/y) 350 350 350 350 350 350Edr = Exposure Duration (y) 30 30 30 30 30 30IRWa = Adult Water Ingestion Rate (L/d) 2 2 2 2 2 2RfDo = Oral Reference Dose (mg/kg-d ) 0.04 0.1 0.03 0.1 2 0.03VFW = Volatilization factor 0.5 0.5 0.5 0.5 0.5 0.5IRAa Adult Air Ingestion Rate (m3/d) 20 20 20 20 20 20RfDi = Inhalation Reference Dose (mg/kg-d ) 0.05714 0.05714 0.014285 0.05714 NA 0.014285TC = Target Concentration for HQ of 1 (ug/L) 324 374 95 374 73000 95Monitor Well Sample Identification 

C5-C8 C9-C12 C9-C10 C9-C18 C19-C36 C11-C22 Aliphatics Aliphatics Aromatics Aliphatics Aromatics Aromatics

Input Concentrations (ug/L) 

RHMW02 420 270 270

RHMW02D 490 270 280 

Calculated Hazard Quotients 

RHMW02 4.4 0.7 2.8 

RHMW02D 5.1 0.7 2.8 

* To calculate the baseline risk HQ (versus the target HQ) the formula is rearranged and uses the measured concentration

** Represent rounded values. 
15 

1.6 CONCLUSIONS AND RECOMMENDATIONS

Since 2005, revisions to regulatory requirements and environmental investigations in Hawaii 

associated with hydrocarbons in groundwater have provided new perspective on evaluating risk 

at these sites. 

At the Facility, the U.S. Navy has an extremely important mission in supplying fuel to the 

Pacific Fleet. This is complicated by environmental issues associated with past hydrocarbon 

releases to the underlying drinking water aquifer. Prior to groundwater monitoring Round 16 in 

July 2009, the site-specific groundwater model and Action Levels associated with the past and 

hypothetical future petroleum releases from the site were based in part on results from USEPA 

Method 8015 Modified for TPH-GRO and TPH-DRO. 

As discussed in the previous sections of this document, MADEP fractionation methods for VPH 

and EPH may be more relevant for quantifying risk associated with petroleum mixtures and in 

determining when specific actions should be taken to mitigate future releases. For example, the 

Round 16 sample result for TPH-DRO at RHMW01 (248 g/L) indicated that the EAL for TPHmiddle distillates (210 g/L) were exceeded at this location, whereas no MADEP fractions were 

detected in this sample. MADEP fractionation analysis provides advantages over the traditional 

TPH analysis. First it divides the gasoline and middle distillate range TPH analysis in three subfractions for each range. This provides more accurate health risk analysis. The second advantage 

is that only the petroleum hydrocarbons are included in analytical results. 

Round 16 results seem to indicate that in all but one of the wells tested, the TPH results were 

probably petroleum breakdown products or from some non-petroleum source. This ambiguity in 

TPH results is somewhat problematic regarding petroleum contaminant groundwater monitoring 

at the facility. The consistent future use of MADEP fraction analysis may be able to resolve 

uncertainties associated with Facility TPH results. 

The Tier 1 Human Health Risk Assessment conducted on MADEP factional results indicated 

that groundwater underlying RHMW02 exceeded the acceptable HI of 1.0 by a factor of 

approximately 8, assuming the most conservative residential potable water scenario. However, 

MADEP fractions were not detected in samples from RHMW01 or RHMW03 within the 

Facility. RHMW01 is located directly southwest of Tanks 1 and 2, and currently assumed to be 

hydrologically downgradient from all USTs in the Facility and upgradient from the U.S. Navy 

Well 2254-01. 

The absence of detectable MADEP fractions in RHMW01 may indicate that contaminants are 

not migrating in significant concentrations toward the U.S. Navy Well 2254-01 under July 2009 

conditions. The assumed groundwater flow direction is the worst case scenario for contaminant 

transport from beneath the tanks to the drinking water well. Any significant divergence from this 

groundwater flow direction would move contamination away from the drinking water well. 

Based on observations described in this letter report, it is recommended that consideration be 

given to including MADEP analyses in the analytical groundwater monitoring program. Using 

the combination of TPH-GRO/TPH-DRO and VPH/EPH analytical results, will allow a more 

thorough assessment regarding actual petroleum contaminant risks posed by the Facility to the 

U.S. Navy Well 2254-01 or other area drinking water supply wells. 
16 

However, using a different analytical method to evaluate Facility risk requires the concurrence of 

HDOH. Therefore, it is recommended that the Navy and TEC consider entering into discussions 

with HDOH to use MADEP fractionation analysis to supplement the current TPH analysis with 

the possibility of at some point, replacing TPH analysis with the MADEP analytical 

methodology. 

Please don’t hesitate to contact me if you have any questions regarding this Letter Report at 

either 808-528-1445 or my cell at 865-742-2181. 

Sincerely, 

Rick Adkisson 

TEC Project Manager 
17 

ATTACHMENT 1 

Differences Between MADEP and 8015C Analytical Methods
18 

Differences Between MADEP and 8015C Analytical Methods 

There are basic differences between analytical method 8015C and the MADEP method that can 

result in differing results for split samples analyzed by both methods. A general explanation of 

the methods is helpful in order to understand these differences. 

Petroleum hydrocarbons in the environment, especially older weathered samples, are complex 

mixtures of not only aliphatic and aromatic hydrocarbons, but also breakdown products of 

petroleum and other organic materials. Total petroleum hydrocarbon (TPH) analytical methods 

such as 8015, MADEP, and others are non-specific methods that attempt not to identify and 

quantify individual compounds, but rather measure all purgeable or extractable hydrocarbon 

compounds within a “range” that corresponds to the boiling points of hydrocarbons. These 

boiling point ranges generally correspond to gasoline and diesel. Quantification of the amount of 

either gasoline range (GRO or VPH) or diesel range (DRO or EPH) petroleum hydrocarbons in a 

sample is accomplished by summing the individual concentrations of all compounds detected 

within specified ranges. It is the definition of these ranges that gives rise to most of the 

significant differences between the 8015C and MADEP VPH results. 

By definition, method 8015C specifies the quantification range of GRO from C6 – C10 (nhexane to n-decane). This corresponds to compounds that elute from a chromatographic column 

between 2-methylpentane and 1,2,4-trimethylbenzene. MADEP defines VPH as ranging from 

C5 – C12 (n-pentane to n-dodecane), which corresponds to those compounds that elute from npentane up to naphthalene. The attached set of chromatograms illustrates the effect of the 

differing ranges. The top figure is a reference chromatogram showing the retention times of the 

four compounds that define the two ranges, and the lower figure shows an actual sample. Note 

that there are petroleum hydrocarbons that elute after 1,2,4-trimethybenzene, but before 

naphthalene. These compounds would not be quantified in an 8015C analysis, but would be 

quantified in a MADEP VPH analysis. This is why 8015C GRO results could be reported at 

lower concentrations than MADEP VPH results. 

Beyond this very simplistic explanation, there are other more significant discriminators between 

the two methods. The Hawaii Department of Health (HDOH) has approved the use of MADEP 

analytical methods at Air Force sites within Hawaii that have residual contamination from 

historic fuel releases. This is primarily because the MADEP methods prescribe a 

cleanup/fractionation step (EPH only) and results are obtained and presented separately for 

aliphatic and aromatic compounds according to ranges: C5 – C8; C8 – C12; C9 – C18; and C19 

– C36 for aliphatic compounds and C9-C10 and C11 – C22 for aromatic compounds. Thus, the 

MADEP method provides much greater specificity than is typically achieved through 8015C 

methodology. 

Given the increased specificity and the required silica gel cleanup, the MADEP method may 

provide greater insight into not only the age of the petroleum hydrocarbons (many petroleum 

breakdown products will be removed from the extract during the silica gel cleanup), but also 

provide indications as to how site conditions may be changing over time. TPH methods will 

only present trends (increasing/decreasing TPH concentrations) while the greater number of 
19 

“analyte” ranges in MADEP results allows for analysis of shifts to heavier or to lighter range 

hydrocarbons as well. 

 

Finally, the MADEP VPH and EPH methods were “designed to complement and support the 

toxicological approach developed by the Massachusetts Department of Environmental Protection 

to evaluate human health hazards that may result from exposure to petroleum hydrocarbons.” As 

described in INTERIM FINAL PETROLEUM REPORT: DEVELOPMENT OF 

HEALTH-BASED ALTERNATIVE TO THE TOTAL PETROLEUM HYDROCARBON 

(TPH) PARAMETER, (prepared for the Bureau of Waste Site Cleanup, Massachusetts 

Department of Environmental Protection by Office of Research and Standards Massachusetts 

Department of Environmental Protection) . This approach provides for: 

“...an alternative approach to the analysis and interpretation of the "TPH" parameter used 

at oil contaminated waste sites. The alternative can be used to perform site-specific risk 

assessments or to develop health-based cleanup standards for petroleum hydrocarbons. 

Rather than quantifying the entire range of petroleum hydrocarbons as one mass, a 

technique is used which divides the broad chemical classes of petroleum hydrocarbons 

(alkanes, cycloalkanes, alkenes and aromatics) into subgroups of compounds based on 

numbers of carbon atoms in the compounds in each subgroup and translates the masses of 

compounds in each specific segment into discrete estimates of health risk for specified 

exposure scenarios.” 

Standard 8015 analysis does not provide the chemical divisions necessary to conduct analogous 

calculations. 

Because of the greater specificity that the MADEP analytical method provides, it is 

recommended that the Navy and TEC consider entering into discussions with HDOH to use 

MADEP fractionation analysis to supplement the current TPH analysis with the possibility of at 

some point, replacing TPH analysis with the MADEP analytical methodology. By collecting 

split-samples to be analyzed by method 8015C and the MADEP method, this would allow for the 

establishment of baseline results for each method. Then at some point, pending HDOH 

approval, analysis by method 8015C could possibly be discontinued since the MADEP analytical 

method provides more information than the 8015 method. 

Attachment D 

TICs Memorandum 
 April 19, 2010 

January 2010 Sampling Event at the Red Hill Facility 

TPH-DRO at RHMW02 

The January 2010 total petroleum hydrocarbon, diesel range organics (TPH-DRO) results at RHMW02 

were significantly impacted by two large peaks identified by the laboratory as caprolactam and DEET. 

These tentatively identified compound (TIC) peaks were reported as part of the TPH-DRO result because 

according to the analytical method, all peaks within the diesel range must be quantified. However, these 

TICs are apparently unrelated to Red Hill Bulk Fuels Storage Facility (Facility) stored fuels. Caprolactam 

is a monomer used to produce “Nylon 6” and is found in plastics and possibly in paints and floor polishes. 

DEET is a pesticide commonly used as an insect repellent. 

Neither of these TIC compounds was detected as part of the laboratory extraction or instrument quality 

control process (e.g., method blanks, instrument blanks, and laboratory control spikes). Also, caprolactam 

and DEET are not used or found in the SGS laboratory that performed the analysis. Therefore, the TICs 

are not laboratory introduced contaminants. In addition, the same field personnel performed the January 

sampling and their sampling approach was identical to that used in previous Facility sampling events. 

Furthermore, the field personnel were extremely careful and cognizant not to introduce any contaminants 

to the collected and/or shipped samples. Consequently, it is not believed that the TICs were introduced via 

the analytical or sampling/shipping process. 

As shown in Table 1, these two significant TIC peaks (i.e., identified by the laboratory as caprolactam 

and DEET) contributed significantly to the reported TPH-DRO results. Although the TPH-DRO 

analytical method requires that all peaks in the diesel range be quantified for the “officially reported” 

TPH-DRO result, Table 1 estimates what the respective TPH-DRO concentrations would have been 

without the two TIC peaks. The reprocessing or re-quantification results were provided by the laboratory. 

These “adjusted concentrations” more closely represent what would be anticipated with normal and 

duplicate samples. 
Table 1 – January 2010 RHMW02 Analytical Results** 

January 2010 

Results 

Official TPH-DRO Result 

(g/L) 

Estimated TPH-DRO Result 

without the two TIC peaks 

included (g/L) 

RHMW02 2,130 1,740 

RHMW02D 

(duplicate sample) 

3,410 2,110 

Table 1 Note: ** TICs are “tentatively identified” compounds. The TPH-DRO analytical method is not 

specific (i.e., is designed to quantify any and all organic compounds within the diesel range). By scanning 

the TPH-DRO extract via GC/MS, unknown peaks have been “tentatively identified” (i.e., without the 

benefit of “neat” standards and the use of specific methods designed to accurately quantify the particular 

TIC peaks “identified”). Therefore, although the TICs are believed to be the “identified” compounds, there 

is some inherent uncertainty associated with this identification process. This uncertainty is why the 

“officially reported” TPH-DRO result must quantify all the organic compounds within the TPH-DRO 

range. 

 

In summary, these TICs from the January 2010 sampling event are apparently not attributable to stored 

fuels at the Facility, they are not laboratory contaminants, and it is unlikely that they were introduced by 

the sampling/shipping process. 

TPH-DRO at RHMW05

Similar to RHMW02, the January 2010 TPH-DRO result for RHMW05 was significantly impacted by 

two large peaks identified by the laboratory as caprolactam and DEET. These TIC peaks were reported as 

part of the TPH-DRO result because according to the analytical method, all peaks within the diesel range 

must be quantified. However as mentioned above, these TICs are apparently unrelated to Facility stored 

fuels. Caprolactam is a monomer used to produce “Nylon 6” and is found in plastics and possibly in 

paints and floor polishes. DEET is a pesticide commonly used as an insect repellent. 

As with RHMW02, neither of these TIC compounds was detected as part of the laboratory extraction or 

instrument quality control process (e.g., method blanks, instrument blanks, and laboratory control spikes). 

Also, caprolactam and DEET are not used or found in the SGS laboratory that performed the analysis. 

Therefore, the TICs are not laboratory introduced contaminants. In addition, the same field personnel 

performed the January sampling and their sampling approach was identical to that used in previous 

Facility sampling events. Furthermore, the field personnel were extremely careful and cognizant not to 

introduce any contaminants to the collected and/or shipped samples. Consequently, it is not believed that 

the TICs were introduced via the analytical or sampling/shipping process. 

As shown in Table 2, these two significant TIC peaks contributed significantly to the reported TPH-DRO 

results. Although the TPH-DRO analytical method requires that all peaks in the diesel range be quantified 

for the “officially reported” TPH-DRO result, Table 2 estimates what the respective TPH-DRO 

concentrations would have been without the two TIC peaks. The reprocessing or re-quantification results 

were provided by the laboratory. 
Table 2 – January 2010 RHMW05 Analytical Results** 

January 2010 

Results 

Official TPH-DRO Result 

(g/L) 

Estimated TPH-DRO Result 

without the two TIC peaks 

included (g/L) 

RHMW05 2,060 541 

Table 2 Note: ** TICs are “tentatively identified” compounds. The TPH-DRO analytical method is not 

specific (i.e., is designed to quantify any and all organic compounds within the diesel range). By scanning 

the TPH-DRO extract via GC/MS, unknown peaks have been “tentatively identified” (i.e., without the 

benefit of “neat” standards and the use of specific methods designed to accurately quantify the particular 

TIC peaks “identified”). Therefore, although the TICs are believed to be the “identified” compounds, there 

is some inherent uncertainty associated with this identification process. This uncertainty is why the 

“officially reported” TPH-DRO result must quantify all the organic compounds within the TPH-DRO 

range. 

 

In summary, these TICs from the January 2010 sampling event are apparently not attributable to stored 

fuels at the Facility, they are not laboratory contaminants, and it is unlikely that they were introduced by 

the sampling/shipping process. 

February 2010 Re-sampling Event at the Red Hill Facility 

TPH-DRO at RHMW02

Per the Facility Groundwater Protection Plan, because of the January 2010 results for RHMW02, the 

monitoring well was re-sampled in February 2010 for TPH-DRO. The February 2010 TPH-DRO results 

for RHMW02 were significantly impacted by three relatively large TIC peaks. The first peak (i.e., likely 

caprolactum) provided the largest TIC contribution toward the “officially reported” TPH-DRO 

concentration. The second peak was initially thought to be DEET, but following additional analyses, was 

identified to likely be dodecanoic acid. The third TIC peak was not able to be identified, even after 

subsequent analyses. 

These three TIC peaks were reported as part of the TPH-DRO result because according to the analytical 

method, all peaks within the diesel range must be quantified. Caprolactam is a monomer used to produce 

“Nylon 6” and would be found in plastics and possibly in paints and floor polishes. Dodecanoic acid is 

not used or found in the SGS laboratory and was not found as part of the laboratory quality control 

process (e.g., instrument and method blanks), thus is not a laboratory contaminant. The third TIC peak 

that contributed to the “officially reported” TPH-DRO concentration could not be identified, even given 

subsequent analyses. 

Chromatograms from the February laboratory data depict the two TIC peaks (i.e., identified as 

caprolactam and dodecanoic acid) that apparently are unrelated to Facility stored fuels and the third 

unknown TIC compound. The three peaks are summarized on the chromatograph as follows: 

 The first peak marked (~2 minutes) should be caprolactam/nylon6. This is the largest TIC peak 

and is the major TIC contributor to the “officially reported” TPH-DRO result. 

 The second peak marked (~4 minutes) was initially thought to be DEET, but following 

subsequent analysis was identified as likely to be dodecanoic acid. 
 The third peak marked (~6.6 minutes) is an unidentified/unknown compound (i.e., not identifiable 

following an 8270 analytical method TIC library search). This peak was also present on the 

chromatograms for the January 2010 TPH-DRO sample results, but was much smaller and did not 

significantly influence the “officially reported” January TPH-DRO results. 

Note that none of these three TIC peaks appear as part of the associated laboratory quality control process 

(e.g., method blanks and instrument blanks). 

Table 3 depicts the “official reported” TPH-DRO results that include all three TIC peaks described above. 

Table 3 also estimates what the TPH-DRO results would be in the event that the three TIC peaks (i.e., 

likely caprolactam, dodecanoic acid, and an unknown compound) were not present. This reprocessing or 

re-quantification of the chromatograms was performed by the laboratory. 

Table 3 – February 2010 RHMW02 Analytical Results** 

February 2010 

Results 

Official TPH-DRO 

Result (g/L) 

Estimated TPH-DRO Result 

without the three major TIC peaks included

(g/L) 

RHMW02 8,650 3,470 

RHMW02D 

(duplicate sample) 

6,910 2,930 

Table 3 Note: ** TICs are “tentatively identified” compounds. The TPH-DRO analytical method is not 

specific (i.e., is designed to quantify any and all organic compounds within the diesel range). By scanning 

the TPH-DRO extract via GC/MS, unknown peaks have been “tentatively identified” (i.e., without the 

benefit of “neat” standards and the use of specific methods designed to accurately quantify the particular 

TIC peaks “identified”). Therefore, although the TICs are believed to be the “identified” compounds, there 

is some inherent uncertainty associated with this identification process. This uncertainty is why the 

“officially reported” TPH-DRO result must quantify all the organic compounds within the TPH-DRO 

range. 

In summary, for the February analytical results, the first two TICs (and possibly the third TIC) are 

apparently not attributable to stored fuels at the Facility and they are likely not laboratory contaminants. 

Also, it is believed that none of these three TIC peaks have been significant contaminants of past Facility 

TPH-DRO reported concentrations prior to the January and February 2010 sampling events. In addition, 

the same field personnel performed the February sampling and their sampling approach was identical to 

that used in previous Facility sampling events. Furthermore, the field personnel were extremely careful 

and cognizant not to introduce any contaminants to the collected and/or shipped samples. Consequently, 

TEC does not believe that the TICs were introduced via the analytical or sampling/shipping process. 

One identifiable variable that occurred during the January and February sampling events that was not true 

with earlier rounds was the ongoing process of dismantling/removing temporary PVC collection pipelines 

and the demobilization of various equipment and supplies from the tunnel complex. It is unclear how or if 

these occurrences may have had any effect/influence on the January and February 2010 TPH-DRO 

results. 
March 2010 Re-sampling Event at the Red Hill Facility 

TPH-DRO at RHMW02

Per the Facility Groundwater Protection Plan, because of the February 2010 results for RHMW02, the 

monitoring well was re-sampled in March 2010 for TPH-DRO. These sampling results (normal and 

duplicate samples) did not show large concentrations of the TICs described above that are apparently nonfuel related. Furthermore, the TPH-DRO concentrations more closely approximate the levels that have 

been historically observed from RHMW02. Table 4 presents the RHMW02 TPH-DRO March 2010 

results. 

Table 4 – March 2010 RHMW02 Analytical Results 

March 2010 Results Official TPH-DRO Result 

(g/L) 

RHMW02 2,630 

RHMW02D (duplicate 

sample) 

2,350 

Please feel free to contact me if you have any questions or comments on my cell phone at 865-742-2181. 

Sincerely, 

Rick Adkisson 

TEC, Project Manager 
 

Attachment E 

Assessment of Potential Toxicity Posed by Polar Byproducts 
Zemo & Associates LLC

986 Wander Way 

Incline Village, NV 89451 

775-831-6179; dazemo@zemoassociates.com 

FINAL DRAFT 

July 11, 2008 

Mr. Jeff Hart, R.G. 

Principal, Senior Project Manager 

TEC Inc. 

1001 Bishop Street, Suite 1400 

Honolulu, HI 96813 

Subject: Assessment of Potential Toxicity Posed by Polar Byproducts Resulting from 

Biodegradation of Petroleum Hydrocarbons 

Hickam Air Force Base, Pearl City, Hawaii 

Dear Mr. Hart: 

This letter presents a summary of findings regarding the potential toxicity posed by polar 

compounds dissolved in groundwater that result from intrinsic biodegradation of petroleum 

hydrocarbons. Polar compounds in the semivolatile range have been detected in groundwater 

associated with a historic gasoline release at Hickam Air Force Base, Site 18, Pearl City, 

Hawaii. The Hawaii Department of Health (HDOH) has requested that the Air Force justify the 

use of the Massachusetts Department of Environmental Protection (MADEP) fractionated 

analysis for Extractable Petroleum Hydrocarbons (EPH), which does not measure the polar 

component, to calculate risk associated with the middle distillate petroleum fraction in 

groundwater at ST18. The HDOH alternative risk calculation approach has been to assume 

that the middle distillate petroleum fraction can be measured using the United States 

Environmental Protection Agency (USEPA) Method 8015 modified, which includes the polar 

component, and then assumes the maximum toxicity (based on the C11 to C22 aromatics 

petroleum fraction) for the entire mixture to calculate risk. Evidence presented in this letter 

favors the use of the MADEP analysis and fractions for determining risk, and justifies the 

assumption that the toxicity associated with the polar component is negligible compared to the 

petroleum fraction. On this basis, this letter presents the following: 

1. A primer regarding the chemistry of petroleum hydrocarbons and their polar 

biodegradation byproducts; 

2. An assessment of the analytical methods and technical issues associated with both 

MADEP and USEPA Method 8015mod protocols for petroleum mixtures; 

3. A description of the potential toxicities of the petroleum fractions as defined by MADEP 

compared to the potential toxicities of the polar biodegradation byproducts; and 

4. Conclusions that support the use of the MADEP fractionated analysis for risk 

assessment purposes rather than the USEPA Method 8015mod analysis because the 

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potential toxicity posed by the polar compounds appears to be negligible compared to 

the C11 to C22 aromatics petroleum fraction. 

Chemistry of Petroleum Hydrocarbons and Biodegradation Byproducts 

Petroleum hydrocarbons such as crude oils and fuel products are composed primarily of 

aliphatic and aromatic hydrocarbons, which consist of carbon and hydrogen atoms and are nonpolar in their molecular structure. Crude oils and heavier petroleum products such as heavy fuel 

oils can contain large heterocyclic molecules with nitrogen, sulfur, or oxygen in their structure 

(called NSOs), which have increased polarity. Lighter products such as aviation gasoline and 

automotive gasoline (generally C4 to C12) and jet fuels (generally C8 to C18) contain virtually no 

NSOs and therefore virtually no polar molecules, exclusive of additives [Chevron 2000, 2004; 

Zemo and Foote 2003]. The environmental fate of the individual petroleum hydrocarbon 

constituents and the fuel product mixtures is a function of molecular class (aliphatic vs. 

aromatic) and molecular size. With respect to water solubility, it is well established that the 

aliphatics have very low pure-component water solubilities that decrease exponentially with 

increasing molecule size (e.g., the water solubility of the C5 to C8 aliphatics fraction is 11 

milligrams per liter [mg/l], and the water solubility of the C9 to C18 aliphatics fraction is 0.010 

mg/l) [MADEP 2002]. The aromatics are more water soluble, but their pure-component 

solubilities also decrease exponentially with increasing molecule size (e.g., the water solubility 

of the C9 to C10 aromatics fraction is 51 mg/l, and the water solubility of the C11 to C22 aromatics 

fraction is 5.8 mg/l) [MADEP 2002]. Within a fuel mixture, the pure-component solubility of a 

constituent or a fraction is reduced in proportion to its mole-fraction within the mixture, resulting 

in its “effective solubility”. Based on published data, the hydrocarbons in the total measurable 

water-soluble fraction of fresh fuel products are limited to the small aliphatics (less than C8) and 

the aromatics up to about C14 [Zemo and Foote 2003]. 

The microbial biodegradation of petroleum hydrocarbons has been extensively studied due to 

the wide interest in monitored natural attenuation. When petroleum hydrocarbons biodegrade, 

the hydrocarbon molecules are destroyed by sequential oxidation reactions that start with the 

formation of alcohols and proceed to various aliphatic and aromatic organic acids and ultimately 

to carbon dioxide and water; intermediate metabolites can include phenols, ketones and 

aldehydes [Dragun 1988; Barcelona et al 1995]. All of these families of constituents are polar in 

their molecular structure, and therefore are very soluble in groundwater. Because the 

sequential oxidation processes proceed at different rates in different portions of a plume due to 

availability of electron acceptors, the specific polar constituents present in the groundwater will 

vary with time and space. These polar constituents will accumulate where groundwater is 

anoxic, but have been shown to oxidize relatively quickly in the presence of oxygenated water 

[Cozzarelli et al 1994; Cozzarelli and Baedecker 1996; Eganhouse et al 1993]. 

Analytical Methods and Technical Issues 

To assess the concentrations of each of the target petroleum fractions, MADEP developed an 

analytical method that is divided into volatile (purgeable) and extractable petroleum fractions 

(VPH/EPH). For the EPH method, the sample is separated into aliphatic and aromatic fractions 

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via a series of solvent exchanges and using a silica gel column. Silica gel is a highly polar 

material and therefore attracts other polar compounds, and the use of a silica gel column to 

fractionate or clean up samples to reduce interference from non-target analytes is a longstanding EPA method. Because petroleum hydrocarbons are not polar, they are eluted off of 

the silica gel column with the respective solvents. Multiple studies have shown that this MADEP 

analytical method provided acceptable recoveries of the petroleum hydrocarbons present in the 

sample. Although it was not a primary focus of the method, fractionating the sample into 

aliphatic and aromatic hydrocarbons on the silica gel column also isolated the polar nonhydrocarbons that may be present in the sample by retaining them on the silica gel. 

It is widely known that polar non-hydrocarbons are measured as extractable total petroleum 

hydrocarbons (e.g., diesel range organics [DRO]; total extractable petroleum hydrocarbons 

[TEPH]) when methods that do not incorporate a routine silica gel cleanup are used (e.g., 

USEPA Method 8015mod) [Zemo and Foote 2003]. This is because the flame ionization 

detector is not specific to petroleum (it measures all of the organics in the sample), and the 

semivolatile polar compounds can elute in the apparent C10 to C30 range. It has been 

demonstrated that at sites where groundwater was in contact with biodegraded petroleum, up to 

100% of the DRO concentration resulted from polar compounds [Zemo and Foote 2003]. Thus, 

groundwater downgradient from a biodegrading gasoline source can contain measureable 

“DRO” concentrations even though there are no dissolved petroleum hydrocarbons in the 

groundwater sample. 

Potential Toxicities of the Petroleum Fractions 

The potential toxicities of the various petroleum fractions were extensively studied in the mid1990s, and were codified into risk-based regulatory programs in several states. Of note is the 

work performed by the MADEP. MADEP divided the potential ranges of petroleum 

hydrocarbons into volatile fractions (VPH) and extractable fractions (EPH). Each of these large 

fractions is further subdivided into the aromatics and the aliphatic hydrocarbons, which are 

further subdivided into carbon ranges (molecule size). To assess potential risk to human health 

posed by the extractable fraction of petroleum, MADEP requires evaluation of the polycyclic 

aromatic hydrocarbons (PAHs) individually, and then groups the remaining hydrocarbons as the 

C11 to C22 aromatics, the C9 to C18 aliphatics, and the C19 to C36 aliphatics [MADEP 2003]. After 

extensive review of the toxicological literature, MADEP has assigned toxicity properties to each 

of these petroleum hydrocarbon fractions based on either a single surrogate petroleum 

constituent or the properties of a surrogate petroleum mixture [MADEP 2003]. The toxicity of 

the C11 to C22 aromatics fraction is based on pyrene, with an oral reference dose (RfD) of 0.03 

milligrams per kilogram per day (mg/kg/day); the toxicity of the C9 to C18 aliphatics fraction is 

based on laboratory-prepared petroleum mixtures, with an oral RfD of 0.1 mg/kg/day; and the 

toxicity of the C19 to C36 aliphatics fraction is based on white mineral oils, with an oral RfD of 2. 

The uncertainty factors applied when developing each of these RfDs were 3000, 1000, and 100, 

respectively. MADEP updates these RfDs periodically when new petroleum toxicological 

studies become available; values shown are the most current (2003). 

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Potential and Relative Toxicity Posed by the Polar Compounds 

The potential risk to human health posed by the polar biodegradation byproducts has not been 

well studied due to (1) the large number of individual compounds that may be present, (2) the 

transient nature of which compounds may be present, (3) the difficulty in analyzing many of 

these families of compounds, and (4) the assumption that compounds with the polar molecular 

structures would generally be less toxic than the petroleum target compounds (primarily the 

aromatics). While it is impossible to know exactly which specific compounds are present at a 

particular point in time, a practical approach is to estimate the risk posed by these polar 

compounds in a general way by evaluating the available data regarding the toxicities of 

constituents that are representatives of each of these families of polar compounds. For 

example, the 2008 USEPA Regions 3, 6 and 9 Preliminary Remedial Goals (PRG) document 

shows RfDs for four alcohols, three organic acids, two aldehydes, seven phenols and five 

ketones that may plausibly result from the biodegradation of petroleum hydrocarbons. The table 

below summarizes the range of oral RfDs for each of the families of polar compounds for the 

plausible biodegradation byproducts; the average of the oral RfDs (rounded to a single 

significant figure) is also presented for each family of compounds. 

Polar Family No. of Plausible 

Constituents with 

PRG 

Range of 

Oral RfDs 

Factor to RfD of 

0.03 (C11 to C22

aromatics) 

Alcohols 4 0.1 to 0.5 

(Avg 0.3) 

3 to 17 

(Avg 10) 

Organic Acids 4 0.9 to 4 

(Avg 2) 

30 to 133 

(Avg 77) 

Aldehydes 2 0.1 to 0.2 

(Avg 0.2) 

3 to 6 

(Avg 5) 

Phenols 7 0.0006 to 0.3 

(Avg 0.06) 

0.02 to 10 

(Avg 2) 

Ketones 5 0.08 to 5 

(Avg 1) 

3 to 167 

(Avg 43) 

Notes: 

Alcohols – Methanol, n-butanol, isobutyl alcohol, benzyl alcohol. 

Acids – Formic acid, acetic acid, benzoic acid. 

Aldehydes – Formaldehyde, benzaldehyde. 

Phenols – Phenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethlyphenol, m-cresol, o-cresol, p-cresol. 

Ketones – Acetone, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone. 

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The most toxic of the extractable petroleum fractions, the C11 to C22 aromatics, has an oral RfD 

of 0.03. The polar families have oral RfDs that are a factor of about 3 to 167 times higher (less 

toxic), except for the phenols, which range from a factor of 0.02 to 10 higher. The alkylated 

phenols have RfDs that are lower or are about the same as the C11 to C22 aromatics. 

Importantly, the phenols, as well as the aldehydes and ketones, are intermediate metabolites 

that would likely be present in relatively small amounts and for relatively short time periods. The 

alcohols and organic acids are likely the most predominant polar families present in 

groundwater associated with a biodegrading petroleum source; the organic acids have been 

shown to range from about 30% to more than 50% of the total dissolved organic carbon [Thorn 

and Aiken 1998; Cozzarelli et al 1994; Eganhouse et al 1993 ]. Four of the five polar compound 

families have RfDs ranging from about 0.1 to 5, which is a factor of about 3 to 167 times higher 

compared to the RfD of 0.03 for the C11 to C22 aromatics. In addition, using the “average” oral 

RfD for each polar compound family and conservatively assuming that each family comprises 

20% of the total mixture (i.e., giving each family equal weight),the overall average oral RfD for 

these five polar compound families is 0.7, which is a factor of 24 higher than 0.03. Based on 

this evaluation, it is reasonable to conclude that, in general, the toxicities of the polar 

biodegradation byproducts to human receptors are likely significantly lower (1/3 to less than 

1/100, with an average of about 1/24) than the C11 to C22 aromatics petroleum fraction. 

The potential toxicity posed by the polar biodegradation byproducts to aquatic ecological 

receptors has been the subject of a several peer-reviewed studies. The effects from the Exxon 

Valdez oil spill have been studied and it was concluded that although the polar oxidation 

products of petroleum hydrocarbons demonstrated some toxicity, they posed little actual risk to 

the marine organisms because of their high solubility, which results in rapid attenuation in the 

water column [Wolfe et al 1996]. Furthermore, it was pointed out that independent surveys 

showed that sediment toxicity in Prince William Sound declined in only two years to near 

background levels between 1989 (year of the spill) and 1991 [Wolfe et al 1996]. Other studies 

have shown that the polar compounds in the water-accommodated fraction from a biodegrading 

petroleum source demonstrated toxicity, but the response is highly variable depending on which 

taxonomic group and which species were tested [Neff et al 2000; Middaugh et al 1996; 

Middaugh et al 1998; Shelton et al 1999; Carls et al 1999;Heintz et al 1999]. It is also important 

to note that the microcosms and columns used in the various studies may have also been 

impacted by ammonia and sulfide resulting from the petroleum biodegradation, both of which 

are highly toxic to marine organisms [Page et al 2002]. In summary, although there may be 

measureable aquatic toxicity associated with the polar compounds resulting from oxidative 

biodegradation of petroleum, the actual risk is likely very low because the polar compounds are 

not expected to be persistent in surface waters. 

Conclusions 

The constituents in groundwater measured as part of the USEPA Method 8015mod (TPH-DRO) 

analysis and that are removed by the silica gel cleanup are not extractable petroleum 

hydrocarbons, but rather are biodegradation byproducts that are polar in their molecular 

structure. These polar compounds include alcohols, organic acids, phenols, ketones and 

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aldehydes, with the alcohols and organic acids likely being the most predominant. The polar 

compounds are not persistent in oxygenated groundwater. The potential toxicity to human 

health posed by these polar compounds is not well studied, but based on available data for 

plausible representatives of four of the five families of polar compounds with PRGs, it is likely 

that they are less toxic than the C11 to C22 aromatics fraction by a factor of 3 to 167 (1/3 to less 

than 1/100 as toxic). Using the overall average RfD for all five families, which conservatively 

gives each family equal weight, the polar compounds may be less toxic than the C11 to C22

aromatics fraction by a factor of 24 (1/24 as toxic). Therefore, defaulting to the toxicity of the 

C11 to C22 aromatics petroleum fraction as currently requested by HDOH is unjustifiably 

conservative to assess the risk posed by the polar compounds. With respect to the potential 

toxicity posed by the polar biodegradation byproducts to aquatic receptors, these compounds 

appear to result in toxic effects in laboratory studies; however, the polar compounds are not 

expected to be persistent in surface water and therefore the actual risk is likely very low. 

In summary, this evaluation supports the use of the MADEP fractionated analysis to assess risk 

rather than the USEPA Method 8015mod analysis because the potential toxicity posed by the 

polar components appears to be negligible compared to the toxicity of the C11 to C22 aromatics 

petroleum fraction. 

References 

Barcelona, M.J., J. Lu, and D.M. Tomczak, 1995. Organic acid derivatization techniques applied to 

petroleum hydrocarbon transformations in subsurface environments. Ground Water Monitoring 

and Remediation Vol 15, No. 2: 114-124. 

Chevron 2000. Aviation Fuels Technical Review. 

Chevron 2004. Motor Gasolines Technical Review. 

Carls, M.G., S.D. Rice, and J.E. Hose, 1999. Sensitivity of fish embryos to weathered crude oil: Part I. 

Low-level exposure during incubation causes malformations, genetic damage, and mortality in 

larval Pacific herring (Clupea Pallasi), Environmental Toxicology and Chemistry, Vol. 18, No. 3: 

481-493. 

Cozzarelli, I.M. and M.J. Baedecker, R.P. Eganhouse, and D.F. Goerlitz, 1994. The geochemical 

evolution of low-molecular-weight organic acids derived from the degradation of petroleum 

contaminants in groundwater. Geochimica et Cosmochimica Acta, Vol. 58, No. 2: 863-877. 

Cozzarelli, I.M. and M.J. Baedecker, 1996. Biogeochemical fate of organic acid metabolites produced 

during the microbial degradation of hydrocarbons in ground water. U.S. Geological Survey Toxic 

Substances Hydrology Program – Proceedings of the Technical Meeting, Colorado Springs, 

Colorado, September 20-24, 1993, Water-Resources Investigations Report 94-4015: pp. 17-26. 

Dragun, J., 1988. Soil Chemistry of Hazardous Materials, Hazardous Materials Control Research Institute, 

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Vol. 8, Iss. 6: 551-567. 

Heintz, R.A., J.W. Short, and S.D. Rice, 1999. Sensitivity of fish embryos to weathered crude oil: Part II. 

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3: 494-503. 

Massachusetts Department of Environmental Protection (MADEP), 2002. Characterizing risks posed by 

petroleum contaminated sites: Implementation of the MADEP VPH/EPH approach. Policy #WSC02-411. October 31. 

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7

Middaugh, D.P., M.E. Shelton, C.L. McKenney, Jr., G. Cherr, P.J. Chapman and L.A. Courtney, 1998. 

Preliminary observations on responses of embryonic and larval pacific herring, Clupea pallasi, to 

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fractions from biodegraded Alaska North Slope crude oil on embryonic inland silversides, Menidia 

beryllina. Archives of Environmental Contamination and Toxicology, Vol. 42, No. 2: 236-243. 

Neff, J.M., S. Ostazeski, W. Gardiner and I. Stejskal, 2000. Effects of weathering on the toxicity of three 

offshore Australian crude oils and a diesel fuel to marine animals. Environmental Toxicology and 

Chemistry, Vol. 19, No. 7: 1809-1821. 

Page, D.S., P.D. Boehm, W.A. Stubblefield, K.R. Parker, E.S. Gilfillan, J.M. Neff, and A.W. Maki, 2002. 

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William Sound, Alaska, USA. Environmental Toxicology and Chemistry, Vol. 21, No. 7: 1438-

1450. 

Shelton, M.E., P.J. Chapman, S.S. Foss, and W.S. Fisher, 1999. Degradation of weathered oil by mixed 

marine bacteria and the toxicity of accumulated water-soluble material to two marine crustacea. 

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Wolfe, D.A., K.J. Scott, J.R. Clayton, Jr., J. Lunz, J.R. Payne, and T.A. Thompson, 1996. Comparative 

toxicities of polar and non-polar organic fractions from sediments affected by the Exxon Valdez oil 

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(Subtidal Study Number 4), NOAA, Office of Ocean Resources Conservation and Assessment, 

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assessing and regulating dissolved petroleum hydrocarbons in ground water. Ground Water 

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Sincerely yours,