MNA PROGRAMME AT CHLORINATED SOLVENT CONTAMINATED SITE IN CENTRAL ENGLAND

For the past 5 years Ford Consulting Group Ltd has been retained to assist a multinational chemical manufacturing client to understand and address residual organic solvent and other chemical contamination at a former chemical blending facility located in central England.  The work programme has included operational history review (production ceased in ~1990), site investigations/monitoring plus detailed numerical modelling of local and regional groundwater flow and contaminant fate and transport. This was designed to characterise residual soil and groundwater contamination and its migration down gradient within a major aquifer.

The risk to off-site receptor wells has been characterised by detailed quantitative groundwater risk assessment. Whilst the site is associated with a wide range of contaminants including a range of VOCs, petroleum hydrocarbons, trace metals and metalloids, high pH (caustic input) and phosphate, it is the chlorinated solvent species PCE, TCE and TCA and their breakdown products that were the potential risk drivers, because of their mobility and persistence. The mass flux of contamination (including residual contamination) from the site from the mid-1970s onward has been modelled in detail and found to be limited due to natural attenuation (2 orders of magnitude reduction).

An EA approved Monitored Natural Attenuation (MNA) programme has been in place since 2007 and includes quarterly monitoring for a wide range of organic and inorganic contaminants and associated environmental and NA indicators. Ongoing predictive modelling is included. The expected time period for improvement in groundwater quality to <EQS beneath the site boundary in the main aquifer has been predicted to be 10-25 years. Some proactive enhancement of the NA process via residual source area remediation is being considered with a view to reducing this time frame.

TERM CONTRACT AS CONTAMINATED LAND EXPERTS FOR EPA (IRELAND)

In 2009 Ford Consulting Group Ltd was awarded a 2 year Framework Contract to provide expert contaminated consultancy support to the Irish EPA, related to licensed industrial and waste management sites and also other problem sites or areas. In being awarded the contract Ford Consulting Group was awarded full marks for qualifications and work experience, report writing, communication and training skills, work programme design and expected reliability and continuity of service.

The work has so far involved review of contaminated land and groundwater related issues at between 50-100 sites across Ireland, working with the relevant Inspector and sometimes the sites themselves. When site visits are required these usually are to allow greater context to be gained designed to ensure the findings and recommendations made are appropriate. Sometimes it has been used to allow direct communication of findings to the problem holder to allow interaction and discussion of the same.

CORRECTIVE ACTION AT 3 CHLORINATED SOLVENT CONTAMINATED SITES IN SOUTHERN ENGLAND, SCOTLAND & WALES

Ford Consulting Group Ltd has been retained to assist a multinational chemical distribution business in understanding and addressing contaminated land liabilities at their UK facilities. The work programme has included detailed ground contamination source audits coupled with intrusive site investigations and monitoring to characterise residual soil and groundwater contamination.

Where risk assessment has indicated issues of potential concern, further intrusive investigations, remedial feasibility and design studies have been undertaken. Remedial solutions implemented or currently under consideration include soil vapour extraction, groundwater treatment and insitu bioremediation of chlorinated solvents in both soil and groundwater. One remedial system has been in place for 2 years, with the other two sites currently at the final feasibility and design phase.

LANDFILL RESTORATION & MANAGEMENT PROGRAMME, NORTHERN ENGLAND

FCG has been programme managing the final restoration and post closure monitoring of a chemical waste landfill site in Yorkshire.  FCG managed the detailed design, procurement and construction quality assurance for a new cap incorporating a geosynthetic clay liner to minimise surface infiltration through the top of the landfill.

The new clay cap includes for the capture and discharge of clean surface water runoff via a perimeter ditch and new sewer ~400m along a public highway to allow discharge into an existing culverted stream.  Control of flow to the sewer was achieved by a new attenuation lagoon sized for a 1:100 year rainfall event, plus 20% for climate change, together with a hydro-brake device to restrict the flow rate.  A new 300m long overflow pipeline to a secondary stream was also constructed.  Restoration of the landfill margins with 800m of new access roads, major earthworks to create less steep slopes, hydro-seeding and tree planting are also included in the scheme.

Relatively low pH and highly mineralised landfill leachate has impacted local groundwater quality although quantitative risk assessment has been used to demonstrate an absence of risk to a wider environment. In the recent past void creation in the waste, due to low-pH controlled dissolution has resulted in order of magnitude changes in groundwater movement through the landfill. This is expected to continue to be important (expected to last for up to five years) and consideration is being given to a short to medium term programme of groundwater abstraction and treatment.

TEESSIDE CORRECTIVE ACTION PROGRAMME

Ford Consulting Group designed, procured, installed and is now operating and maintaining a multi-facetted Corrective Action Programme exceeding a total value of £1.2M at an operational chemical production facility in Teesside.  A series of individual work packages have been completed comprising the following:

• Cleaning and repair of existing effluent drainage system
• Repair and upgrade of road tanker chemical/waste offloading area including tank farm bunds to avoid future losses of to the ground
• Cleaning, inspection and upgrade of production building specific effluent collection sumps to include controlled storage and management of out of specification waste streams
• Installation of air emission monitoring platforms for each production plant main emission stack
• Installation of an active containment system to intercept and recover groundwater beneath and down gradient of the main tank farm area, which is contaminated with mainly petroleum hydrocarbons and solvents

FCG completed the detailed design, specification, competitive tendering, engagement of the successful bidder, contract management, site supervision and reporting for the programme works.  Operation, maintenance and performance monitoring of the groundwater remediation system will continue for an expected 3-5 year period.