Environmental Assessment Best Practices For Construction Excavation Sites

Sustainability awareness on construction sites is on the rise and its effect on the environment have become increasingly relevant. Large quantities of materials, water, energy and other resources are consumed, each impacting the environment in a different way.

Repurposing excavated material and reducing hauling distances can save a lot of time and money while reducing the impact on the environment. But there are several steps that need to be followed before the excavated material could be moved and repurposed on another construction project.

We asked Steve Boyce, an associate from Active Earth Engineering Ltd. to shed some light on the process.

When it comes to excavation sites, what type of environmental assessment is typically required before the excavated material can be hauled to another property such as a fill site or another construction project site?

In order for soil to be considered “clean”, the chemical quality must be within the Contaminated Sites Regulation (CSR) standards that apply at the site accepting the material, which is usually referred to as the “receiver site”. While there is no explicit regulatory requirement for soil to be tested before it is relocated, the reality is that testing is the only way to confirm the soil quality.

Testing typically involves engaging a Qualified Environmental Profession (QEP) to collect soil samples for analysis at a certified laboratory, and to interpret the results. The findings are typically then reviewed by the owner/operator of the proposed receiver site (or their QEP), to confirm whether the material is acceptable. The number of samples and analysis program will depend on many variables, including the volume of soil being relocated, the potential sources of contamination identified, and the receiver site’s specific requirements. Samples are usually analyzed for metals and various hydrocarbons at minimum, and salts analysis (Sodium and Chloride) is increasingly being considered necessary.

In my opinion, an appropriate testing program is also the best way to mitigate liabilities, considering that all parties involved in soil relocation are responsible for complying with the CSR, including contractors and site owners/operators. Some receiver sites may still accept soil based on a “clean” Phase I Environmental Site Assessment (ESA) or Stage 1 Preliminary Site Investigation (PSI) report, but we’re finding this is now fairly rare. The main reason is that these types of reports only comment on the identified potential sources of contamination, based on a site visit and desktop records review; they do not include actual soil testing. In practice, a “clean” Phase I ESA report provides limited assurance to the owner of a fill receiver site.

What are the soil quality categories provided under the CSR, and how does this relate to soil relocation?

The answer to this is a bit complicated, but bear with me! The CSR provides different soil standards for different land uses, including Wildlands (natural or reverted), Agricultural, Urban Park, Residential (low or high-density), Commercial, and Industrial. The standards that apply for soil relocation are determined not by zoning, but by the primary land use at grade at the receiver site. For several parameters, the applicable standards also depend on the specific environmental conditions at the receiver site, such as the proximity to water bodies (e.g. streams) or whether the groundwater below the site could be used for drinking water. This means that the standards that apply at one site may be very different from those that apply at another site, even if both sites have the same land use designation.

There’s some room for a QEP to interpret the testing results. Various regulatory tools are available for evaluating whether apparent “exceedances” truly represent “contamination”. For example, we may be able to use statistics to “weed out” anomalous results (e.g. one sample with a marginally elevated concentration of one parameter), or we may be able to show that a result is within an established “regional background concentration”. As is often true, the devil is in the details.

There are numerous soil quality terms used by the BC Ministry of Environment and Climate Change Strategy (ENV), such as “Commercial Quality Soil” or “Waste”. There are at least as many terms used informally by industry, such as “RL-minus”, “CL-plus”, etc. In my opinion, these terms can cause confusion and should be used carefully. I prefer to describe soil as being chemically suitable or chemically not suitable for specific sites or specific land uses.

What is the breaking point for determining if fill can go to a commercial “clean fill” dump site or if it needs to go to an authorized contaminated soil facility?

If chemical concentrations in the soil exceed the CSR standards that apply at your chosen “clean fill” site, the soil cannot be relocated to that site. At that point, your options include:

  1. Obtaining an Authorization from ENV to allow the soil relocation. The most common example is a Contaminated Soil Relocation Agreement (CSRA), though these can be expensive and time consuming and have become less relevant following the 2017 regulatory changes.
  2. Relocating the soil to an alternate “clean fill” site that can accept the soil (i.e. a receiver site where less conservative CSR standards apply).
  3. Relocating the soil to a site where CSR standards do not apply, such as some fill sites that operate on First Nations lands. A QEP retained by the Band Council or the facility’s operator typically reviews the test results to confirm acceptability. 
  4. Disposing of the soil to an authorized contaminated soil facility.

What happens to material that is disposed to an authorized contaminated soil receiver facility?

The soil is often first placed into a soil management or treatment area, where is may be mixed with other soil, stabilized, or treated in some manner such as bioremediation (bacterial hydrocarbon breakdown). However, many contaminants cannot be effectively or economically “treated” to remove the contamination. The soil is typically placed into an engineered landfill for permanent storage. These are usually lined, with leachate collection and treatment systems, and regular environmental monitoring programs. The soil may also be retested by the facility operator, to confirm the actual contaminant concentrations prior to landfilling.

Some authorized facilities may act as “transfer stations”, and may simply treat/stabilize the soil before transporting it to another facility for permanent storage.

Anything else you’d like to add?

I’d just like to reiterate that understanding and applying the CSR standards correctly is not straightforward, and really does require a qualified and experienced professional. Soil that is determined to be “clean” or “suitable for relocation” for one receiver site could very well be considered “contaminated” or “unsuitable” for another site.

A quick side note: the CSR standards changed significantly in late 2017. As such, the conclusions of older soil testing reports may no longer be valid, and the data should be reviewed by a QEP to determine how the results compare to current standards.

If you need any additional information or assistance with soil testing or disposal, our team at Active Earth is ready to help.

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Steve Boyce, B.A (Env), LEED G.A.
Active Earth Engineering Ltd. 


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