final remediation implementation work plan

Final Remediation Implementation Work Plan

Former Pepeʻekeo Sugar Company Property 29-2306 Old Māmalahoa Highway, Hakalau, Hawaiʻi

TMK (3) 2-9-002:079 and 081

Prepared for SHROPSHIRE GROUP LLC

P.O. Box 1146 Hilo, Hawai’i 96721

Submitted December 6, 2019

Prepared by Insight Environmental LLC

HC3 Box 13132 Kea‘au, Hawai‘i 96749

www.InsightHawaii.com IE415

This Final Plan is prepared for: Shropshire Group LLC P.O. Box 1146 Hilo, Hawaiʻi 96721

SIGNATURE PAGE

FINAL REMEDIATION IMPLEMENTATION WORK PLAN FORMER PEPEʻEKEO SUGAR COMPANY PROPERTY 29-2306 OLD MĀMALAHOA HIGHWAY HAKALAU, HAWAIʻI TMK (3) 2-9-002:079 AND 081

Project Number: IE415

December 6, 2019

Evan Pfaff, P.E. Environmental Engineer Insight Environmental LLC HC 3 Box 13132 Keaau, Hawaiʻi 96749 www.InsightHawaii.com

Final Remediation Implementation Work Plan December 2019

IE415-Insight Environmental LLC ii …Insightful Solutions

TABLE OF CONTENTS

SIGNATURE PAGE ............................................................................................................................. i

TABLE OF CONTENTS .................................................................................................................... ii

LIST OF ABBREVIATIONS .............................................................................................................iii

1.0 INTRODUCTION AND PURPOSE ....................................................................................... 1

2.0 BACKGROUND ........................................................................................................................ 1

3.0 REMEDIATION ACTIONS ..................................................................................................... 5

3.1 FENCING AND SIGNAGE OF ARSENIC CONTAMINATION AREA ..................................... 5 3.2 EVALUATION OF FISHING ACCESS TRAIL .............................................................................. 5

4.0 DOCUMENTATION ................................................................................................................ 7

REFERENCES ..................................................................................................................................... 8

FIGURES Figure 1. Property Location Map ....................................................................................................... 2 Figure 2. Property Vicinity Map......................................................................................................... 3 Figure 3. Property Map ....................................................................................................................... 4


IE415-Insight Environmental LLC iii …Insightful Solutions

LIST OF ABBREVIATIONS

bgs below ground surface

DU decision unit

EAL Environmental Action Level

ESA Environmental Site Assessment

HDOH Hawaii Department of Health

HEER Hazard Evaluation and Emergency Response

µm micrometer

mg/kg milligram per kilogram

mm millimeter

MIS multi-increment sample

TMK Tax Map Key

TGM Technical Guidance Manual

XRF x-ray fluorescence


IE415-InsightEnvironmental LLC …Insightful Solutions 1

1.0 INTRODUCTION AND PURPOSE

This final remediation implementation work plan presents the actions to be taken for the protection of human health and the environment over a portion of the Former Pepeʻekeo Sugar Company property identified by Tax Map Key (3) 2-9-002:079 and 081, and located at 29-2306 Old Māmalahoa Highway, Hakalau, Hawaiʻi. The location of the property is identified on Figures 1 and 2. Figure 3 presents a map of the property. The purpose of this plan is to outline the actions to be taken to satisfy the requirements of Condition 6, identified in a July 12, 2018 letter from the Hawaii Department of Health (HDOH) Hazard Evaluation and Emergency Response (HEER) Office to the Hawaiʻi County Planning Department (State of Hawaiʻi Department of Health, 2018). Specifically, Condition 6 requires:

a. Install a secure fence around the existing ‘arsenic contamination area’ (former pesticide storage and mixing area) identified as contaminated or potentially contaminated in previous testing, to prevent public access. The specific boundary of the fenced off area to be approved by the HDOH HEER Office. Appropriate signage indicating no public access due to contaminated soils will be posted on the fence in multiple locations that are clearly visible upon approach.

b. Conduct representative soil sampling for arsenic contamination along the fishing access trail location on the bounds of the fenced-off contaminated area to confirm soil arsenic levels are below applicable HDOH action levels. If this testing reveals soil contamination above applicable HDOH action levels, either the fenced off area will be expanded to include all the area found to be contaminated (and the fishing trail relocated), or appropriate action will be conducted and completed to remove the soil contamination from the area outside the fence.

2.0 BACKGROUND

In September 2007 and January 2008, the HDOH HEER Office performed soil sampling and analysis at the property. The soil sampling and analysis identified elevated arsenic concentrations in property soils. Bioaccessible arsenic was measured in one sample at 102 milligrams per kilogram (mg/kg). This soil would be categorized as HDOH Arsenic Soil Management Category D; heavily impacted soil requiring remedial action (Integral Consulting Inc., 2014).

In 2009, a Phase II Environmental Site Assessment (ESA) was conducted to determine the presence and extent of soil contamination. The Phase II ESA collected and analyzed surface soil multi-increment samples (MIS) from decision units (DU) located at various locations across the property. The Phase II ESA also utilized a field portable x-ray fluorescence (XRF) instrument to screen the entire property for arsenic, lead, and mercury. The Phase II ESA excavated trenches within the area of suspected arsenic contamination.

Copyright:© 2013 National Geographic Society, i-cubedFigure 1. Prop erty Location Map

Draft Rem ediation Im p lem entation Work PlanForm er Pep e̒ekeo Sugar Com p any Prop erty29-2306 Old Mām alahoa Highway

Hakalau, Hawai̒iTMK (3) 2-9-002:079 and 081

Decem ber 2019Page 2

0.25 0 0.25 0.5Miles

1 in = 0.5 miles

q

Property

Hawai'iIsland

Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics,CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS UserCommunity, Esri, HERE, DeLorme, MapmyIndia, © OpenStreetMapcontributors

200 0 200 400Feet

1 in = 400 feet

qProperty

Figure 2. Prop erty Vicinity MapDraft Rem ediation Im p lem entation Work PlanForm er Pep e̒ekeo Sugar Com p any Prop erty29-2306 Old Mām alahoa Highway

Hakalau, Hawai̒iTMK (3) 2-9-002:079 and 081

Decem ber 2019Page 3

Hawai'iIsland

Figure 3. Property MapDraft Remediation Implementation Work Plan Former Pepeʻekeo Sugar Company Property

29-2306 Old Māmalahoa HighwayHakalau, Hawaiʻi

TMK (3) 2-9-002:079 and 081December 2019

Page 4

Basemap from Final Removal Action Report, Former Pepeekeo Sugar Company Property, Hakalau, Hawaii. Integral Consulting Inc. 2014.

Warehouse B

LEGENDArsenic Contamination Area FencingFishing Access Trail

Warehouse A

DU2

DU1



Composite samples were collected from various depths within the trench profile and screened with the XRF instrument. Lastly, the Phase II ESA analyzed a subset of samples from the XRF screening for analysis of total and bioaccessible arsenic (Integral Consulting Inc., 2014).

The Phase II ESA found that only arsenic was a chemical of concern at the property. The Phase II ESA also found that arsenic soil concentrations greater than 100 mg/kg were principally confined to the area of the former pesticide mixing area and the area downslope of the pesticide mixing area. An isolated location on the east end of the property as well as an area around the northwestern warehouse (Warehouse B) also had arsenic soil concentrations greater than 100 mg/kg. Screening of the samples collected from the test trenches found arsenic soil concentrations greater than 100 mg/kg in several of the trenches. The Phase II ESA evaluated XRF screening data against bioaccessible arsenic analysis and found that arsenic in surface soils had a bioaccessibility of approximately 8%. This led to the conclusions that surface soil XRF screening results of greater than 288 mg/kg would be equivalent to an HDOH Arsenic Soil Management Category C or higher (Integral Consulting Inc., 2014).

In June 2014, a Final Removal Action Report was prepared that evaluated options for removal actions that would allow the property to be used for residential land use. The evaluation selected on-site consolidation and capping at the source area as the best removal action (Integral Consulting Inc., 2014). In June 2014, the HDOH HEER Office approved the selected removal action. The selected removal action was not implemented, and current future use plans are directed at reuse of Warehouse A and B at the west end of the property.

3.0 REMEDIATION ACTIONS

This section identifies the remediation implementation actions to be taken.

3.1 FENCING AND SIGNAGE OF ARSENIC CONTAMINATION AREA

Approximately 715 feet of secure fencing will be installed around the arsenic contamination area to prevent public access. The fencing will consist of 5-foot “hog wire” or range fencing. The fencing will be supported with “T-posts” installed at 10-foot intervals with a 6-inch diameter wooden post installed every 50 feet. The fencing will be securely anchored to the posts with staples or tie wire. A vehicular access gate will be installed along the south or west side of the fence to facilitate maintenance of the fence and the fenced area. The gate will be secured. The proposed location of the fencing is shown on Figure 3.

A warning sign of no less than 12 inches by 18 inches, constructed of durable material, will be affixed to the fence at no more than 50 foot intervals. The warning sign will be clearly printed with the words “WARNING -Arsenic-Contaminated Soil – Keep Out”.

3.2 EVALUATION OF FISHING ACCESS TRAIL

Surface soil along the fishing access trail, extending from the end of an asphalt paved driveway to the top of the coastal landing site trailhead will be evaluated for hazards. The proposed



fishing access trail route is shown on Figure 3, is approximately 680 feet long, with the first 320 feet running over an existing asphalt road. The unpaved portions of the trail consist of 160 feet from the end of asphalt road to a southeast corner of the arsenic contamination area fencing, and 200 feet from the southeast corner of the arsenic contamination area fencing to the cliff edge. The 260 feet of unpaved fishing access trail will be maintained as a 4-foot wide pedestrian trail

The first 160 foot section of the fishing access trail, consisting of 640 square feet, will be designated as DU1. The 200 foot section of the fishing access trail, running along the eastern stretch of the arsenic contamination area fencing, consisting of 800 square feet, will be designated as DU2. One surface soil MIS, consisting of 75 increments of soil from 0 to 6 inches below ground surface (bgs), will be collected from each DU for a total of two (2) samples. The soil increments will be collected in a systematic random manner from across the DU using a 1-inch diameter soil trier. The trier will be advanced to 6 inches bgs, and the retrieved core will be containerized in a sealable plastic bag.

Immediately following sample collection, the sample container will be labeled with a unique sample identifier as well as the date and time of sample collection. Visible pieces of vegetation will be manually removed from the sample material. The sample mass will be weighed, and the sample container placed in a cooler with frozen gel ice. The sample will be maintained on frozen gel ice or in a refrigerator until arrival at the analytical laboratory. The sample will be recorded in a field logbook and on a chain-of-custody.

The samples will be transported via commercial carrier to Enthalpy Analytical (Enthalpy) in Berkeley, California. Upon receipt of the sample, Enthalpy will process the sample using a procedure consistent with the HDOH HEER Office Technical Guidance Manual (TGM) (State of Hawaiʻi Department of Health, 2016) for the analysis of MIS (Section 4.2.6 of the TGM). For non-volatile analytes, this procedure involves subsample collection of analytical aliquots after the sample mass has been air-dried and sieved through a 2-millimeter (mm) sieve. For the project samples, following subsampling of the less than 2-mm fraction, the remaining sample mass will be sieved through a 250-micrometer (µm) sieve and subsampled.

All analytical aliquots will consist of a 30-increment subsample and a minimum of 10 grams. All analytical aliquots obtained from the samples will be analyzed for total arsenic using the U.S. Environmental Protection Agency Method 6010B. Enthalpy is accredited by the National Environmental Laboratory Accreditation Program to perform this analysis. Analytical results will be reported on an air-dried basis.

The analytical results for total arsenic (less than 2-mm fraction) will be compared to the HDOH HEER Office Final Tier 1 Environmental Action Level (EAL) for unrestricted land use above a non-drinking water resource and less than 150 meters from surface water, Fall 2017 (State of Hawaiʻi Department of Health, 2017). The applicable EAL is 24 mg/kg. Should the concentration of total arsenic in the samplea (less than 2-mm fraction) exceed the EAL, then the bioaccessibility of the arsenic will be evaluated to determine the HDOH Arsenic Soil Management Category for the DU soil. Based on the proposed use and potential exposure from



the fishing access trail, soils with the properties of HDOH Arsenic Soil Management Category C would be protective of human health. Soils in this category are considered moderately impacted, suitable for commercial/industrial land use only, and exhibit a bioaccessible arsenic of between 23 and 95 mg/kg (State of Hawaiʻi Department of Health, November 2011 [updated September 2012]).

The concentration of bioaccessible arsenic in DU soils will be based on the concentration of arsenic in the less than 250-µm fraction of the sample. The HDOH has determined that bioaccessibility in Hawaiian soils is typically less than 30% and as low as 5% (State of Hawaiʻi Department of Health, 2016). Evaluation of arsenic bioaccessibility in property soils found that bioaccessibility ranged from 1.5% to 6.7% for arsenic concentrations in the less than 250-µm fraction that ranged from 46 to 2,290 mg/kg (Integral Consulting, Inc./Environmental Resources Management, 2009). The concentration of arsenic in the less than 250-µm fraction of the collected sample is expected to be less than 500 mg/kg. As a result, a conservative bioaccessibility of 10% will be applied to the concentration of arsenic in the less than 250-µm fraction of the collected sample. Using a bioaccessibility of 10%, and a maximum bioaccessible arsenic of 95 mg/kg for soils in HDOH Arsenic Soil Management Category C, the maximum allowable concentration of arsenic in the less than 250-µm fraction of the collected samples is 950 mg/kg.

Should the concentration of arsenic in the less than 250-µm fraction of the collected samples be less than or equal to 950 mg/kg, then the route of the fishing access trail will be considered protective of human health and acceptable. Should the concentration of arsenic in the less than 250-µm fraction of the collected samples be greater than 950 mg/kg, then the route of the fishing access trail will not be considered protective of human health and the route will either be modified or additional measures, approved by the HDOH, will be implemented to protect the public from soils along the route.

4.0 DOCUMENTATION

The implemented remediation actions will be documented in a Remediation Implementation Report that documents the installation of fencing and signage, as well as the collection, analysis, and evaluation of the fishing access trail sample. The report will include photographs and documentation of the installed fencing as well as the analytical laboratory report. The report will include the long-term monitoring and maintenance to be performed on the fencing and signage.



REFERENCES

Integral Consulting Inc. (2014). Final Removal Action Report, Former Pepeekeo Sugar Company Property, Hakalau, Hawaii. Waipahu, Hawaii: Integral Consulting Inc.

Integral Consulting, Inc./Environmental Resources Management. (2009). Environmental Site Assessment, Former Pepeekeo Sugar Company Property, Hakalau, Hawaii. Honolulu: Integral Consulting, Inc./Environmental Resources Management.

State of Hawaiʻi Department of Health. (2016). Technical Guidance Manual for the Implementation of the Hawaiʻi State Contingency Plan. Honolulu: State of Hawaiʻi Department of Health.

State of Hawaiʻi Department of Health. (2017). Evaluation of Environmental Hazards at Sites with Contaminated Soil and Groundwater. Honolulu: State of Hawaiʻi Department of Health.

State of Hawaiʻi Department of Health. (2018, July 12). Letter from John Peard of the HDOH HEER Office to the Hawaiʻi County Panning Department Director. Honolulu.

State of Hawaiʻi Department of Health. (November 2011 [updated September 2012]). Update to Soil Action Levels for Inorganic Arsenic and Recommended Soil Management Practices. Honolulu: State of Hawaiʻi Department of Health.

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