Soil_Management_Plan-Final-8-12-2016.pdf

4545 42nd Street, NW

Suite 307

Washington, DC 20016

(202) 375-7900 www.geocapeng.com

August 12, 2016

Mr. Douglas E Bond, PE

McMullan & Associates, Inc.

1861 Wiehle Avenue, Suite 125 Reston, VA 20190

Subject: Contaminated Soil Management Plan, C&O Canal Lock #3 Renovations, Georgetown, Washington, DC (Our

DC15055.01)

Dear Mr. Bond:

GeoCapitol Engineering LLC (GeoCapitol) is pleased to present this contaminated soil management plan during construction. We developed a set of guidelines and recommendations for the handling of contaminated soil on the project for excavation, disposal, and reporting of the on-site contaminated soil.

These services have been performed in accordance with our proposal/agreement dated February 23, 2016 and per the consultant agreement of September 24, 2015.

We understand the C&O Canal Lock #3 will be renovated. The construction methods include excavation of soils behind the canal walls to the base of the canal (approximately elevation EL 17) supported with vertical excavation support. Soil disturbances may include utility work, drilled piles for excavation support, and canal channel sediment removal, in addition to the main excavation behind the canal walls.

Based on the previous chemical laboratory testing and subsurface investigations, portions of the excavation soils on the site are known to have trace to moderate concentrations of petroleum hydrocarbon contamination. The contaminated soils are at depths of approximately 8.5 feet below the existing ground surface (or EL 22). Additionally, any soil that is visually stained, has a petroleum odor, or has photoionization detector (PID) measurements above 10 parts per million should be handled and treated as contaminated. Also, TCLP analysis is recommended to be completed on soil removed from the excavation process prior to disposal at an approved disposal facility. Note that this project does not anticipate hazardous level material. The table below summarizes the material that must be characterized, handled, and treated as contaminated.

Material Type Description

Contaminated

Soil/debris from the excavation behind the canal walls, drilling spoils from installation of the vertical excavation support, utility work, sediment dredge, or other work on site that fit any one or more of the following criteria:

Material excavated below EL 22.

Any material excavated that is visually stained or has a petroleum odor.

Any material with PID measurements greater than 10 ppm.

Sediment dredged from the canal channel.

Material with chemical laboratory testing with elevated petroleum or other contaminant concentrations.

August 12, 2016 DC15055.01 Page 2

It should be noted that several soil, groundwater, and sediment samples have been collected over the past

5 to 6 years. There is no known source of the contamination as it appears to be migrating from an unknown off-site location. The site is being affected by another adjacent properties continual contamination of groundwater. National Parks Service is attempting to take corrective action using this Contaminated Soil

Management Plan (CSMP) during their very limited excavation of the site. The excavation only consists of a disturbed area of approximately 1,500 square feet.

The logistics of separating and staging contaminated and non-contaminated soils on site may be limited by the compact size of the work area. Therefore, all excavated materials may be considered contaminated for budgeting and practical space and methodology reasons.

However, if the soil will be separated into contaminated and not contaminated soils onsite, an environmental consultant personnel should be on-site to screen with a PID during excavation and earthwork operations. Also, to assist in further delineation of contaminated soils from non-contaminated soils, test pits can be completed 2 to 3 days ahead of the planned excavation areas, soil screened with a PID, soil samples collected at depths of the planned future excavation, soil samples submitted for chemical laboratory analysis, and an excavation timeline can be developed by the on-site environmental consultant.

The test pits and soil samples may allow for confirmation of petroleum contaminated soils and further delineation to reduce the amount of contaminated soils from being hauled to a remediation disposal facility.

PID and Soil Sampling Methodology Soil samples will be screened with a PID (MiniRAE 2000 monitor or equivalent) to detect the presence of volatile organic compounds (VOCs). Grab soil samples will be collected from discrete areas and put in plastic Ziploc bags, allowed to volatilize for approximately 15 minutes. The PID reading will be collected by inserting the tip of the PID into the headspace of the Ziploc bag.

Composite soil samples will be collected from representative areas of proportional amounts of material in the Ziploc bag.

Chemical Laboratory Jar Soil Sample Methodology The grab soil jar samples should be collected using standard environmental protocol, including:

Lab certified, clean 4-ounce soil jars

Label each sample with date, time, project, and sample identification

Maintain samples in cool temperatures and analyze prior to holding time

New gloves with contact of each sample to minimize cross-contamination

Jars filled with minimal headspace

The soil sample may be collected from the bucket of the backhoe, shovel, or hand auger equipment. Care will be taken so that the sample is obtained from the center of the material on the backhoe to minimize cross-contamination from the bucket sides. The jar soil samples will be transported to a NELAP accredited chemical laboratory under chain-of-custody procedures. Analysis of soil jar samples will consist of the parameters listed in the table below.

Soil Sample Parameter Test Method

Total Petroleum Hydrocarbons-Diesel Range Organics (TPH-DRO) EPA method 8015

Total Petroleum Hydrocarbons-Gasoline Range Organics (TPH-GRO) EPA method 8015

Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX) EPA method 8021

The excavator/contractor should ensure that either the excavated contaminated material is removed from the site on the same day, or is staged in water-tight containers so that precipitation does not cause run-off. Poly (plastic sheeting) should be placed to cover excavations overnight to prevent entry of precipitation

August 12, 2016 DC15055.01 Page 3 into the excavation areas. Also, the contractor should limit practices that may mix contaminated and not contaminated material. If not contaminated material is inadvertently mixed with contaminated materials, the not contaminated material that was mixed will have to be disposed of as if it is contaminated.

The excavator shall provide the anticipated disposal facility or end location for the contaminated material prior to excavation. The receiver of the soil may have additional testing requirements above the local regulations and those specified for this project. Material that is considered contaminated must be removed from the site and hauled to an approved disposal facility (i.e. Soil Safe, Clean Earth, or equivalent).

Contaminated soils are expressly forbidden from being re-used on site.

Groundwater should be lowered below the excavation depth prior to soil excavation work. Contaminated soils should not be saturated during transport offsite and should pass the paint filter test prior to being loaded onto trucks. In order to do so, a DCRA and/or DC Water permit must be obtained by the general contractor prior to construction. Any water impacted by the project shall be pumped to an appropriate treatment system in order to comply with Water Quality Standards of the District of Columbia in Title 21 of the District of Columbia Municipal Regulations (DCMR) Chapter 11, and the Water Quality Monitoring

Regulations in Title 21 DCMR Chapter 19 and/or the discharge requirements of DC Water.

The civil engineer has completed a canal water bypass plan which was submitted under separate cover to address water in the canal before, during, and after construction. Mr. Tim Vaughan of Adtek Engineers worked with National Park Service (NPS), US Army Corp of Engineers (USACE), DOEE, and other interested regulators to address appropriate regulatory requirements regarding the canal water. The general contractor shall comply with requirements set forth by the Civil Engineer

This methodology has been developed to properly, safely, and efficiently characterize the soils during handling on the site. If new information or conditions develop, this soil management plan and methodology should be revised accordingly.

These services were performed in accordance with generally accepted environmental practices. No warranties, expressed or implied, are made as to the professional services included in this report.

We appreciate the opportunity to be of service for this project. Please contact the undersigned if you require clarification of any aspect of this report.

Sincerely, GEOCAPITOL ENGINEERING LLC

Ashley Hogan, PG

Senior Geologist

Daniel F. Gradishar, PE

Principal

CR/AH/DG/kf G:\PROJECTS\Active DC15 Projects\DC15055.01 C&O Canal env\Final\2. Contaminated Soil Management Plan\Soil Management Plan-Final-8-12-

2016.docx