Significance Evaluation Methods

There are currently a plethora of evaluation tools that have currently been developed, and all have their advantages and drawbacks. It is the decision of the company as to which method is to be adopted although it is recommended that it is not too complicated. The company may decide to wish to tailor a method to suit there own requirements, for example, they may wish to alter the wording, or even to devise a method themselves. It is beyond the scope of this module to provide an exhaustive list, although the examples below will give you a good idea of the methods available.

Method 1

A simplistic approach is given in the flow chart below to firstly assess significance, and then to evaluate significance through using a scoring method. View an example of a completed Register of Effects using this method.

If an effect is assessed to be significant, the following method shall be applied to indicate how significant this effect is :

Evaluating Significance

The environmental impacts shall be evaluated to determine their significance as follows:

Firstly, a score from 1 to 3 shall be assigned on the probability of the impact occurring

1 Unlikely to happen during normal, abnormal or emergency situations
2 May happen during normal operations
3 Certain/almost certain to occur during normal operations
 

Next, a score from -3 to 3 shall be assigned on the severity of the impact

-3 Will cause a highly significant reduction in environmental damage
-2 Will cause a significant and measurable reduction in environmental damage
-1 Will reduce environmental damage to a limited extent
1 Has the potential to cause limited damage to the local and global environment
2 Will result in damage to the environment
3 Will result in a major environmental incident
 

Finally, multiply the probability and severity scores together to get a Significance Index. Adverse environmental impacts are represented by a positive score (+), whereas beneficial impacts are represented by a negative score (-). Impacts with an Index number equal to or lower than -6, or equal to or greater than 6 are considered to be significant.

Method 2

For each impact identified you should award a score to show the relative performance under normal operating conditions of:

  • Legislation (existing and proposed)
  • Damage to the environment: level of toxicity, acidity, polluting potential
  • Interested parties: public, investor's, employees etc
  • Quantity: waste volumes or occurrence frequencies.
 

The matrix given below gives an example how effects can be given scores/ratings under normal operating conditions.

Matrix to score environmental effects under normal operating conditions

Score Weighting Factor
Legislation Existing Impending   None X 2 = A
Environmental impact Known detriment Possible detriment Limited detriment No detriment X 3 = B
Interested parties Considerable interest Moderate interest Little interest No interest X 2 = C
Quantity High Medium Low Nil X 3 = D
Normal operating conditions total score = (A+B+C+D)

The same type of table can be used to assess the significance under other operating conditions to show the impact of:

  • Abnormal operations, eg start up of the factory following summer shut down
  • Accidents or emergency situations
  • Historical activities, such as those of past occupiers
  • Planned activities eg. Proposed production line/product and further site development

These four scores can then be added together to give a total score (table 4) which can be used to rate and rank the effects under the different operating conditions.

Matrix to score environmental effects under different operating conditions

  12 6 3 0  
Abnormal operations   Increased environmental impact No change Reduced environmental impact = A
Accident/emergency   Increased environmental impact No change Reduced environmental impact = B
Historical activities Evident/requires action Possible damage/difficult to evaluate   No damage = C
Planned activities   Increased environmental impact No change Reduced environmental impact = D
Total score of other operating conditions = (A+B+C+D)

Once you have established a score for each effect, it is up to you to finally establish the overall significance of effect using your knowledge of the company and the site.

Format of the Register

The company should decide the format of the register itself, although it is a good idea to have it in the same style as the Quality Assurance (QA) manual and Health and Safety (H&S) manual, especially if the systems are to become integrated.

View Examples: Registers of Environmental Effects

Maintaining the Register

The register should be periodically reviewed by the environmental management team and updated to reflect any changes in the environmental baseline situation.


Read the Hot Metal ltd case study. Attempt to identify the company's significant environmental effects and insert them into a register of your choice using the significance methodology of your choice.