Phase 3 Environmental Site Assessment

What To Expect & Everything You Need To Know To Make Sure You're Prepared So You Can Achieve Site Closure!

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What is a phase III environmental site assessment

What Is A Phase III Environmental Site Assessment?

A Phase 3 Environmental Site Assessment, or (ESA) is a detailed investigation of a site or property that is carried out to determine the extent of present environmental contaminants. Phase III ESAs are carried out after both Phase I ESAs & Phase II ESAs have already been completed.

The primary focus of a Phase 3 ESA is to use the data gathered during the detailed investigation of the site to develop and carry out any required remedial measures to deal with any environmental concerns or liabilities successfully. Phase 3 ESAs typically include:

  • Extensive soil and groundwater testing and analysis.
  • Detailed site investigations.
  • The development of Remedial Action Plan (RAP) required to address the present environmental contaminant or hazard.
  • Site Remediation In Accordance With The RAP

The input from geologists, environmental consultants, property owners, or regulatory agencies can change how the assessment unfolds. However, the extent and requirements of a Phase III ESA will depend on the scope and nature of the environmental concerns or liabilities identified in previous phases (Phase I ESAsPhase II ESAs) of the site assessment. Local and National regulations and guidelines are to be followed during the entire process of this, and all prior ESAs.

Phase 3 ESAs Are To Treat Contaminants

Why Are Phase III ESAs Required?

Phase III Assessments are required to treat any present hazards or contaminants on site. During this assessment, your consultant will investigate any environmental pollutants, hazards, or liabilities discovered in earlier assessment phases. They will go to extraordinary lengths to profile, study and identify the extent of contamination on site. A wide variety of methods may be used during this process.

Then, the findings of your environmental consultant will determine the next steps required to decontaminate your site. Those next steps are known as a Remedial Action Plan or RAP.

Once your environmental consultant has completed their RAP, they will either carry out the RAP themselves or hire a bioremediation company to deal with it instead.

What's Involved In A Phase III ESA

What Does A Phase 3 Environmental Site Assessment Involve

During Phase 3 Site Assessment, your consultant is focused on identifying the scope of contamination so the primary goal of this phase can be completed - environmental remediation.

Various calculations are done to determine the amount of contaminated soil and groundwater. Testing and monitoring are sometimes necessary to determine groundwater flow so that calculations can be more accurate.

Your remediation team will use certain characteristics specific to your site, such as the different uses of the property. They can use this information to determine the likely state of contamination to aid in their research.

Once their research has been completed and they have enough information to form a proper remedial solution, work will be done to begin dealing with any contaminants present on site.

Below we'll walk you through two of the main ways the contamination will be dealt with - either on-site (in-situ) or off-site (ex-situ) remedial techniques will be used.

Ex-Situ Remediation

Ex-situ remediation generally involves using machinery to excavate, treat, or dispose of contaminated materials off-site. Suppose it is decided that treating the material is best. In that case, they will bring the soil to a facility designed to destroy any present hazards, contaminants, or pollutants in the material, and they will bring it back once this process is finished.

If, however, it's decided it would be best to remove the contaminated soil and replace it with a material free of the identified contaminant, this can also be done.

The main advantage of this method is that it can be done very quickly. However, the most significant disadvantage to this approach is that if any contaminants are missed during excavation, they can continue to spread through groundwater and may lead to more work and costs in the long run. Another disadvantage to ex-situ remediation is that it is much more expensive than in-situ remediation, which we'll discuss next.

In-Situ Remediation

In-situ remediation techniques are generally more reliable, but the main downside is that they typically take longer to work than solutions offered with ex-situ remediation. The typical in-situ project duration lasts around three months from the beginning until the contaminant is destroyed.

Certain conditions can take this time anywhere from 6 months to multiple years - which is also true for ex-situ methods. The best way to ensure your site closure doesn't take years is to find an environmental remediation company with a proven track record displaying they can destroy contaminants present on-site.

The main benefit is that you avoid the cost of excavation, handling hazardous materials, treating them in a specialized facility, and either returning or replacing them. In-situ is generally a much more cost-effective way to deal with any present environmental contaminants or liabilities.

In-situ methods often involve using appropriate machinery to drill down to the contaminant zones and distribute adequate amounts of remedial reagents required to reduce and destroy contaminant concentrations.

Some forms of drilling can be various forms of DPT technology, sonic drilling, rotary drilling, etc. However, DPT technology has proven to be one of the most cost-effective means of drilling because there is virtually no waste left post-treatment. In contrast, with traditional rotary drilling, you would have to pay to deal with contaminated drill cuttings, for example.

However, one of the most reliable methods for in-situ remediation has been proven to be soil mixing. With soil mixing - using excavation equipment - your remediation specialists can ensure the required reagent can make 100% contact with all the contaminated material.

Remedial Action Plan (RAP)

What Is A Remedial Action Plan (RAP)

"RAP" stands for Remedial Action Plan. A RAP is a plan designed by your environmental consultant. A RAP aims to lay out the required remediation methods necessary to successfully target and destroy any present contaminations found in the soil or groundwater of a site.

In addition to the treatment method required, it also lays out the estimated time needed to carry out any treatment methods strategically and efficiently.

Usually, the consultant will outline important information such as the cost, time, and remedial services required to treat the existing contaminants.

6 Steps To A Phase 3 ESA

6 Steps To A Phase III ESA

  • Determine The Extent Of Contamination Discovered In Phase 2
  • Estimate Impacted Soil & Groundwater
  • Consider Which Remedial Technique Is Best
  • Complete RAP
  • Notify regulatory agencies
  • Destroy Contaminants

1. Determine The Extent Of Contamination Discovered In Phase 2

At the beginning of a Phase III ESA, the remediation team will focus on further profiling the state and scope of contamination so they can better understand what they are facing. Phase II ESAs are just about confirming that environmental hazards exist, but Phase III is where they begin to understand to what extent a hazard exists.

2. Estimate Impacted Soil & Groundwater

Once they have a good grasp of the scope of the contaminant, they will begin to determine the overall state of the contamination zone. What are its dimensions, the groundwater's flow rate, and how much groundwater and soil are contaminated?

Consultants will typically use the previous uses the property has had historically to help determine these figures in more detail.

3. Consider Which Remedial Technique Is Best

Based on their findings, they will determine which remedial technique is best after the contamination has been further identified and assessed. In addition to the state of the site, they will also consider external things such as the available budget.

4. Complete RAP

Once these variables have been carefully weighed and a remedial technique has been chosen, they will complete their remedial action plan.

5. Notify regulatory agencies

Before certain parts of Phase 3 can be complete, certain regulatory agencies need to be contacted and notified.

6. Destroy Contaminants

Once the RAP is finished, the appropriate agencies have been notified, all paperwork is completed, and an environmental remediation team has been hired, remediation can begin, and the contaminants can be destroyed.


In conclusion, a Phase III ESA is where the contaminant is further profiled and destroyed. Generally, consultants will require either ex-situ remediation (off-site) or in-situ remediation (on-site) to deal with any present contaminants.

In-situ remediation is generally more reliable and affordable, but it takes longer. Ex-situ remediation is more expensive and isn't as reliable, but it is generally much faster than in-situ techniques.

Get Your Site Back Today

Environmental Remediation Specialists

Remember, while DeepEarth Technologies, Inc. passionately shares knowledge and educates on various topics, we do not offer site assessment services. Our services are specialized in site remediation.

If you've got a site contaminated with hydrocarbons or chlorinated solvents, you can either give us a call, request a quote, or contact us with any questions to be connected to an environmental specialist.

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