Cleaning of Mercury Contamination in Gabraith Street

in Squamish, B.C. Canada

8 March 2004

Presented by Lindsey Dunn

Saleh Salim

Introduction

Canadian Occidental Petroleum Ltd. (COPL) operated chlor-alkali plant from 1965-1991

Property owned by BC Rail and BCR Properties Ltd., plant owned by FMC of Canada Ltd.

Location

The plant is located on Gabraith Street in Squamish British Columbia, Canada.

45 acres just south of downtown Squamish

The property is enclosed by the Howe (South), Cattermole Creek (West), and Mamquam Blind Channel (East)

The soil on site is a dredged sediment over formal tidal floats and saltwater marches

Chlor-Alkali Processes

Caustic soda and chlorine are produced by the electrolysis of an aqueous solution of sodium chloride (brine)

Approximately 4.2% of mercury released in atmosphere from chlor-alkali

Due to environmental concerns, mercury processes since abandoned and ion-exchange membrane technology used

Source of Mercury Contamination

Plant discharged and spilled mercury into the land, water, and air as a result of plant processes.

“Old Lagoon” was named as it was a main discharge area for discharge sludge from wastewater treatment diluted with saltwater

From 1965-1974 (pre-environmental standards) plant discharged 2-31 kg/day or 1000-10,000 kg/year of mercury into the environment

1974-1991: 1 kg/day or 370 kg/year discharged

Resulting Contamination

On site: the soil contained 65,635 m3 of waste with Hg levels > 2ppm, 22,905 m3 of special waste (Hg >100 ppm), ground water found to have unacceptable Hg levels (>2ppm)

– “Old Lagoon” held 36,000 m3 of Hg contaminated sludge, half of which could be considered “special waste”, ground water held dissolved mercury at levels 100x standards)

– Surface vegetation found to have elevated levels of mercury Off site: High levels of Hg found in sedimentation of water ways

Channel, Creek Highest levels found in Mamaquam Blind Channel at SW corner of

property near dock Howe Sound lake bottom organisms, aquatic vegetation, and general

aquatic life (fish, birds, crabs, ect) found to have mercury traces

Risks associated with Mercury

Mercury causes adverse effects to the human and environmental health

Mercury changes to methylmercury by a chemical reaction in organic environments

Methymercury then has the ability to bio-accumulate within a food chain where by humans are at the greatest risk as the rate in which mercury is removed from the body cannot match the rate in which it is ingested.

Problems due to Contamination

Canadian Occidental petroleum Ltd(COPL) forced to change name to Nexen

Nexen paid Millions Site left unused Over 1700 rails cars of contaminated

soil shipped to landfill

Environmental Impacts

Kills Aquatic life Destroys vegetation Make land unusable Effects can be seen

in generations to come

Alternative Remediation Technique

Precipitate Flotation method Causes heavy metals to precipitate with

iron elements in soil Completely leaves site pollutant free Compact device allowing onsite

cleaning up Separates contaminates from soil, thus

allowing soil to be buried back onsite

Remediation Efforts

COPL and BC Rail agreed to complete voluntary clean-up but never completed work

Mandatory remediation was then required to a depth of 3 m

Difficulties included the hydrostatigraphy, tidal influences, presence of surface impoundments in the form of effluent and peroxide ponds, hydroecolgocial complexity

Cost equal to $45 million Carried out by Nexen Inc. (formally COPL)

Remediation Techniques

Ground water recovery and treatment

Contaminated soil and sludge excavation and stabilization

Soil Washing

Techniques Considered

Electrochemical Remediation Technologies (ECRTs)– Strong electrical current sent through ground to

remove metals and mercury– Limited because not economical for large areas

– Location concerns: If mercury were to be mobilized it could send a large amount of concentrated mercury directly into aquatic environment surrounding site

New Mercury Capturing Technique Presented by Noram Engineering and

Constructors Ltd at 2002 Remediation Technologies Symposium

Uses lignin derivatives and a flocculating agent to remove and stabilize metal contaminants from contaminated water

Uses a lignin-ferric absorbent material to capture and immobilize metals in soil

Groundwater Remediation

Technique similar to wastewater treatment of suspended soils

Lignin dissolved in captured groundwater so that it bonds to free mercury

Coagulate to form colloidal lignin-mercury particles Ferric chloride added to flocculate the mix and

cause mercury to fall out of suspension Result is groundwater with Hg < 1g/l and a non-

leaching mercury sludge

Soil Remediation

Soil mixed with a solid ferric-lignin adsorbent

Absorbent captures mercury in order to stabilize and immobilize

Contaminated soil extracted and disposed

Current State

BC Rail transferred 71 acres, worth $35 million, of clean land to the town of Squamish

Waterfront property will be commercially and residentially developed in preparation of the 2010 Olympics which will be held in BC