Preservation Matters: Disasters- Oil Spill Response for Cultural Resources

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Immovable cultural resources such as historic buildings, structures, landscapes, and archeological sites need specialized care during an oil spill response. The preassessment, health and safety precautions are detailed in the Preservation Matters Brief Oil Spills and Cultural Resources. Cleaning should be considered where the recovery actions are not causing more harm than leaving the oil in place. Pre-approvals are required from the Regional Response Teams (RRTs) for using chemicals for cleaning the oil spill.

This document is an instructional guide for use by members of the response community responsible for the management and preservation of cultural resources. The information provided is based on research done at National Center for Preservation Technology and Training
(NCPTT).

This brief discusses two cleaning methods used in the research at NCPTT using surface washing agents on the Environment Protection Agency’s (EPA) list.

The cleaning methods are defined for hard materials such as fired brick, sandstone, and concrete. The instructions and recommendations do not apply to materials that are not listed. For soft surfaces such as plasters, wood, adobe, unfired brick, etc. please consult a preservation specialist for guidance.

Disclaimer: Surface washing agents mentioned are on the U.S. Environmental Protection Agency’s NCP Product Schedule. This listing does NOT mean that the EPA approves, recommends, licenses, certifies, or authorizes the use of these products on an oil discharge. The listing means only that data have been submitted to EPA as required by Subpart J or the National Oil and Hazardous Substances Pollution Contingency Plan, Section 300.915

SWAs used in Phase III of the research on the removal of Crude oil from cultural resources

Vrinda Jariwala, NPS

Surface Washing Agents (SWAS)

The US. Environmental Protection Agency’s National Contingency Plan product schedule includes Bioremediation Agents, Miscellaneous Oil Spill Control Agents, Dispersants, and Surface Collect-ing Agents along with Surface Washing Agents. The product schedule has Surface Washing Agents (SWAs) in two categories based on their oil removal mechanism.

• Lift and disperse agents
• Lift and float agents

Lift and dispersing agents or surfactants have a detergency mechanism to emulsify the oil, dispersing it in water. In contrast, the Lift and float agents or solvers dissolve or lift oil, forming surface slicks that can be recovered from the water.

The SWAs selected should be low in toxicity, pH neutral, and easily available.

Katherine Langdon compares poultice recipes for crude oil removal at Fort Livingston, Grand Isle, LA.

NCPTT, NPS

Testing Protocols

Do

• Select the SWA type (lift and float or lift and disperse) and the cleaning action (1 or 2) based on the kind of contamination, substrate, oil, and weathering.
• Prepare the SWA solution as per the manufacturer’s directions and test on contaminated surrogate samples before cleaning larger areas. Try both methods of cleaning with a minimum strength of SWA solution and increase the strength based on the success of the treatment.

Do Not

• Use distilled or deionized water at low pressure (500psi or less) for cleaning. If distilled or deionized water is not available, test the water for salts, use at low pressure 500psi or less.
• Use a soft brush for cleaning with the least pressure needed to remove the oil.
• Once the test is successful, manageable areas of 1 square foot should be cleaned at a time.

Tools and materials required (top to bottom)- Spray bottle, safety glasses, WypAll L40 Roll (DRC), hand and nail brush, cotton linters for making poultice, N-95 face mask, and Nitrile gloves

Vrinda Jariwala, NPS

Tools and Materials

• Double Re-creped (DRC) bonded cellulose wipes such as WypAll L40
• Soft bristle nylon brushes such as hand & nail brushes
• Spray bottle for the preparing the SWA solution
• Cotton linters for making poultice
• Portable hydro cleaner like Worx Hydroshot portable power cleaner 320 PSI.
• Commercial blender
• Plastic wrap such as Saran Wrap
• Low adhesion tapes such as Painter’s tape
• Personal Protection Equipment as detailed in Preservation Matters Brief Oil Spills and Cultural Resources.

Gently brush the surface in a circular motion. Use a spray bottle to spray the SWA solution on the surface.

Vrinda Jariwala, NPS

Procedure 1: Using Surfactant SWA

Hard surfaces: Brick, Sandstone and Concrete

Brick when oiled with light to medium or heavy viscosity oil tends to absorb the oil because of the brick’s high porosity. In the case of heavy viscosity oils some bricks may have a slick layer on the surface.

In the case of sandstone and concrete, when oiled with light to medium or heavy viscosity oil there was a slick layer can form on the surface.

These procedures were developed for brick, sandstone and concrete; lime and cement mortars were not assessed alongside these materials.

Clean using spray and agitate method

Cleaning brick, sandstone and concrete exposed to unweathered light to medium viscosity oils is easier when done at the earliest time after oil contamination.

Preparation

Begin the process by preparing the SWA solution (where applicable) based on the manufacturer’s instructions concerning the level of soiling.

Application

• Spray a SWA solution of ~1 mL (approximately 1 squirt from the spray bottle) per sq inch of the area. A manageable area of 1 sq ft may be cleaned at a time. Allow 10 minutes of contact. For vertical surfaces such as walls, start from top to bottom.
• After 10 minutes, agitate with a soft bristle nylon brush for 2 minutes (for one sq. ft. of surface area) in a circular motion.
• Spray an additional solution of ~1 mL per sq inch and agitate.
• Spray the final amount of solution of ~1 mL per sq inch and allow additional minutes of contact.
• After 10 minutes, agitate with a soft bristle nylon brush for 2 minutes (for one sq ft of surface area)

Cleaning

Using clean water and hydro-cleaner (500 PSI or lower) rinse the resource very well. Use the hydro-cleaner for vertical surfaces like walls from top to bottom.

Note: Frequently rinse the brushes with clean water and hydro-cleaner to remove the oil or surface material that has been collected in the bristles.

Clean using surfactant poultice method

If after three repeated brushings the oil is still visible a poultice treatment can be used. It works well on the weathered material exposed to unweathered light-to-medium viscosity oils or heavy oils.

Surface Washing Agent solution with the cotton linters before blending

Vrinda Jariwala, NPS

Preparation

• Begin the process by preparing the surfactant SWA solution based on the manufacturer’s instructions concerning the level of soiling.
• In a blender, mix 50 grams(g) (loosely packed) shredded cotton linters to a fine and fluffy texture.
• Mix the 500mL SWA solution with the linter to make a wet pulp (the amount of cotton and SWA solution may vary depending on the surface, but the ratio should remain the same). A pulp will emerge after a minute.

Application

• Before applying the poultice, thoroughly wet the contaminated surface with distilled or deionized water.
• Apply SWA-cotton pulp directly on the surface. Use approximately 5g of poultice on 1 sq inch, such that it covers the contaminated area with a 5-10 mm (0.2 to 0.4 inch) thick pulp.
• Cover the poultice with a plastic bag/Saran wrap that doesn’t let the poultice dry out. The wrap should be big enough, and the edges can be secured using a low adhesion tape such as painter’s tape.

Removal and Cleaning

• After leaving the poultice for a minimum of 2 hours and up to 6 hours, carefully remove the plastic wrap.
• If the poultice is dry, agitate in a circular motion with a soft bristle nylon brush (for one sq. ft. of surface area) for 2 minutes.
• Using clean water and hydro-cleaner (500 PSI or lower) rinse the resource well. Use the hydro-cleaner for vertical surfaces like walls from top to bottom.
• Repeat this process of rinsing and scrubbing(agitating) for a total of three rinses. Do not scrub after the final rinse to avoid recontamination.

Sandstone samples cleaned with Procedure 2 the poultices of SWA Naturama G3 A-5 and Solvents; top row – De-Solv-It- Industrial Formula and bottom row Cytosol. The oiled samples on the extreme right are control samples oiled with weathered Access Western Winter Blend

Vrinda Jariwala, NPS

Procedure 2: Using a Solvent and Surfactant Combindation

Hard surfaces: Brick, Sandstone and Concrete

Brick, sandstone, or concrete surfaces exposed to heavy viscosity oils which are difficult to remove using the first procedure should be treated with a combination of two different SWAs.

Clean using spray and wipe method using solvent SWA

Preparation

• As the solvents (i.e., lift and dissolve SWAs) do not need to be diluted, they should be put in a spray bottle. The solvents dissolve and mobilize the oil, and should therefore be used in controlled quantities.
• Use a DRC wipe. Take one sheet and fold it in half three times to make it 8 layers.

Application

• Spray a SWA solution of ~1 mL (approximately 1 squirt from the spray bottle) per sq inch of the area on the folded DRC wipe. A manageable area of 6 sq inches may be cleaned at a time.
• Use the Solvent absorbed paper and wipe in a circular motion on the contaminated surface for 30-60 seconds. The slick layer of oil on the surface would visibly be wiped.
• Only repeat if necessary, keeping the contact time limited to 30 seconds in each treatment.

Cleaning

Using clean water and hydro-cleaner (500 PSI or lower) rinse the resource well. Use the hy-dro-cleaner for vertical surfaces like walls from top to bottom.

Clean Using Poltice

If after the spray and wipe method the oil is prevalent on the surface or absorbed by the material, then the poultice treatment using a surfactant SWA should be followed as explained in Procedure 1.

Note: The historic surfaces may not be cleaned completely after procedure 1 or 2. There might be stains remaining because of the surface texture, oil, weathering, and time taken for the response.

References

Jariwala, V. “Examination of Surface Washing Agents for Conservation of Oiled Historic Materials Phase III report.” (National Center for Preservation Technology and Training, Inland Oil Spill preparedness program grant, 2021).

National Center for Preservation Technology and Training, “Preservation Matters: Disasters: Oil Spills and Cultural Resources.” (2022).

National Center for Preservation Technology and Training, “Preservation Matters: Disasters- Removal of Wildland Fire Chemicals from Cultural Resources.” (2022).

National Conservation Training Center, “Inland Oil Spill Response for the Department of the Interior.” (U.S. Fish & Wildlife Service, revised 2019).

Salmon, E., “Examination of Surface Washing Agents for Conservation of Oiled Historic Materials Phase I report.” (National Center for Preservation Technology and Training, Inland Oil Spill preparedness program grant, 2019.)

Author and Series Editor

Author: Vrinda Jariwala, Research Associate, NCPTT
Series Editor: Kirk A. Cordell, NCPTT Executive Director
Cover Photo: Jason Church, NPS

About NCPTT
The National Center for Preservation Technology and Training (NCPTT) is a research, technology and training center within the National Park Service. NCPTT publishes its Preservation Matters Series to provide easily accessible guidelines for preserving cultural materials.