Site Assessment - Managing Contaminated Site

Preamble

Spillage is another significant cause of soil contamination. However its succinct or remoteness in disclosure (or undisclosure) has usually evades prompt attention by management. Unless, otherwise in cases of public interest that lured intervention by the authority, contaminated sites are often secluded in the humbleness of an ecological solitary. This silence is ironically dynamic in most cases. Contaminated drinking well water, vegetables farms and the Durian Musang King orchard located at a convenient 500m from an abandoned chemical/oil spill sites, for example, remains salient unless a site assessment is deployed to uncover its scary stealth.

What is Site Assessment?

To identify:

•source

•type

•extent

•risk ... associated with the contamination.

Other Purposes

•Environmental Impact Assessment

•Change of Land Ownership;

•Change of Land Use;

•Pre-Operational Monitoring;

•On Going Operation - Monitoring of Environmental Impact;

•Accidental or Incidental Release -Remediation Assessment.

A case when a diesel fuel tank's valve ruptured and thus
lost it's integrity in the absence of emergency containment.
The spill spread to nearby agricultural crops. How much
damage to this site? What extent of ecological stress?

An environmental site assessment is a process of investigating the sources, types, extent and associated risk on an event of contamination. It also involves identification of possible mitigation and remedial actions with respect to rehabilitation of contaminated sites.
Penilaian alam sekitar keatas tapak yang tercemar dilakukan bagi mengenalpasti punca, jenis, keketaraan dan risiko akibat pencemaran. Ini termasuk mengenalpasti kaedah-kaedah bagi memulihara dan memelihara semula tapak yang tercemar.

A Site Abandonment prior a Stage-1 Site Assessment in 2002
Result: an average of 150mg/L of Nickel compound of the
soil from bore samples around a set of grid. The report was
requested by a European potential buyer of this industrial land.

A site is in the context of environmental management identified by a defined boundary. But, it does not border the mobile and dynamic natural factors, therefore, not restricting transboundary environmental implications – including contaminants (pollutants). Thereby, pollution in one site can affect another through various forms of mobility. As can be seen in the diagram below; the yellow region illustrates that every site has its history whereby every form of utilization generates aspects of environmental concern. This information or data is .. commonly used to determine the position of the site in environmental terms. The red region means the substance description that represents the intrinsic features in the site. It includes mainly physical, biochemical, zoological, botanical and microbiological properties and characteristics. 
Sesebuah tapak mempunyai ciri-ciri yang tersendiri bergantung kepada kedudukan, struktur geografi, sejarah penggunaannya, dan sifat-sifat fizikal, biochemical, haiwan, tumbuhan dan organisma-organisma halus yang secara keseluruhannya mempengaruhi sifat tapak tersebut. 

It is important for one to know ‘what’ and ‘how much’ were contaminating and contaminated. Then, it is crucial to identify its potential associated risk. Risks usually imply liability to the generator of the contaminant. The product from a good site assessment is the execution of accurate method to contain, recover and recycle contaminant and a reasonable rehabilitation of the contaminated site with reasonable effort and affordable costs.
Penilaian alam sekitar keatas sesebuah tapak tercemar membolehkan kaedah pemuliharaan yang sejajar dan sewajar dilakukan.

How has this incident affected the ecosystem of this river
basin? How much is suffering from irreversible effects?
Have we swallowed some of the stuffs somehow ? where?

A proper site assessment shall be able to tell the levels of contamination affecting contaminated sites.

Factors to Consider

•Source, nature, type and constituents of contaminants;

•Geography, topography of contaminated sites;

•Best practices vs. available means of mitigation;

•Recovery, containment and clean-up.

Applications of Site Assessment
Assess pollution levels
Determine associated risks to human (esp. worker) and the environment (natural resources)
Identify liabilities to company
Principles of Site Assessment
Adequacy of data - “the less you know, the more data you need!”
“Don’t pay for data unless you can use it!”
A phased investigation is often more cost-effective.

Phase-1: Site Review

Site Review: based on aerial photography, analysis of land records, physical observations, interviews, records of site history and land use, etc.

How?

>   assess physical and chemical characteristics;

>   determine sampling needs and site management plans;

>   determine contaminant fate and mobility;

>   preliminary field chemical analysis

Note: information is vital - gather as much information!

Phase-2: Assess

Delineation of Contaminant: to determine the track, position and direction of contaminants - vertical and horizontal.

How?

On-site Field Work

 > detail examination

>  sampling activity - affected environmental media.

Data Management

> compilation, interpretation and reporting

Phase-3: Remediate

How?
Excavate and Dispose: transfer of contaminated soil to off-site treatment e.g. Land-farming.
Bio-remediation: Microbial biochemical disintegration and degradation of contaminants.
Air Stripping: removal of volatile compounds during groundwater pumping and treatment.
Soil Vapour Extraction: treating volatile and/or degradable organic contaminants in groundwater and soil below the water table by injection of air
Ozonation: in-situ chemical oxidation system.

Four Physical Conditions of Contamination
Vapour - volatile;
Adsorbed - stick to media surface;
Separate - free product (mobile)
Dissolved - in water or environmental media.

Hydrogeological Settings
Porous Media - unconsolidated solids e.g. silt, sand, gravel, etc.;
Fractured Porous Media - sedimentary formations e.g. sandstone, limestone, etc.;
Fractured Non-Porous Media - igneous & metamorphic rocks e.g. granite, gneiss.
Ground Water

Factors affecting Mass Distribution of Contaminants

Porosity

Permeability

Viscosity

Solubility

Adsorption Capacity

Assimilative Capacity

Leachability

Diagram illustrating the Soil Vapor Extraction
Reference: www.precisionenvironmentalny.com 

Environmental and Physical Factors affecting Migration of Contaminants

Boiling Point

Henry’s Constant

Partition Coefficient

Solubility

Vapour Pressure

Biodegradation

Specific Gravity

Photolytic Degradation

Preliminary Site Survey
Grid system, 200 m2 site = 28 bore holes;
Soil gas surveys with PID monitoring 1/2 to 1 metre depth;
Develop soil vapour contour plan

Today, on this very soil is a cool service condominium
with resort facility!  Who wants to know the past!

Complete Characterization of Site;

Chemicals of concern and characteristics, distribution, limits, mobility of contaminants.

General Water Quality;

Hardness, Dissolved Oxygen, source of contamination

Geologic regional and site conditions;

Hydrogeologic conditions:

Hydraulic properties of aquifer:

Sensitive receptors

Possible off-site receptors, third party property damage

Establish Remedial Action Objective

Could be based on:

Risk Assessment - risk-based clean-up goals;

Established Regulatory Stipulated Clean-up Quality Levels;

Test in-situ Passive Remediation Modelling;

Establishing goals for all environmental matrices and contaminants of concern.

An Untoward Conclusion

Thus, we need to exercise immediate response whenever a spill occur as it's consequence in the long term is vast and rather 'invisible'. All life-cycles known in natural sciences are interacting beyond our normal senses. Well, we don't get to see 'CSDS or MSDS' attached by the price-tags of the Spinach, Ikan Kerapu, Salmon or Durian Musang King for this matter, do we? Worse still, when we buy properties like houses without knowing what they were built on. Was is an ex-mining land that is entailed with TENORM?, demolished oil depot that is smeared with sticky petrochemical stabilizers?, ex-backyard factories contaminated with residual but significant concentrations of toxic heavy metals (other than Metallica)?, or some ex-agricultural land infested with excessive fertilizers, herbicides, biocides, etc.? Conversion of land-use seems rampant in most industrialization processes, but, were they done with environmental responsibility? Well, do we get to see the site assessment report, at least? Should a contaminated site carry the same property value as a 'normal' clean land? The E.I.A? I've not seen any site remediation of contaminated agro-site as a post-EIA activity, has anyone in this country? Well, who owns the EIA and the site? Let's see ... on one hand we have learned about 'bio-accumulation-magnification', what's on the other? A wealthy dish of Sweet-Sour Ikan Kerapu or Salmon Steak which once spraddled between a contaminated mangrove, river, estuarine, natural parks and fishing areas. Let's 'buckle-up'!

Cheerio

Khalid Mohd Ariff

Author,Trainer, and just another ageing man on the streets