Summary and conclusions

Forebyggelse af jord og grundvandsforurening på industrivirksomheder ved udvalgte aktiviteter

The experiences with soil and groundwater contamination over the past decades show that many instances of contamination could have been avoided, for instance by substituting chemicals, focusing on safeguarding the contaminant source or better inspection by the company responsible for or using the site. For many companies, the contaminations have led to extra costs due to investigations, remedial work, breaks in production and impact on reputation. For authorities, the numerous cases have led to costs for investigations and remedial work, as well as the loss of drinking water supplies as a result of having to close extraction wells.

The purpose of the project

The purpose of the project is to act as a manual for companies and authorities for the design, operation and audit of activities which involve a risk of soil and groundwater contamination. The project may be used both with new facilities and for assessment and efforts in relation to existing facilities, including for the preparation of environmental approvals, enforcement orders and audits.

The project lists suggestions for the prevention of soil and groundwater contamination in the following selected industrial activities:

Tank facilities made of metal or plastic for storage of chemicals.
Paving used for the prevention of soil and groundwater contamination.
Areas for storage of chemicals and hazardous waste, washing areas and also filling and distribution areas.
Chemical spills from machinery and facilities as well as during transport and usage.

Screening the risks of industrial activities

When establishing activities, extensions or reassessing existing companies dealing with chemicals, it is necessary to assess whether or not the activity presents any risk of soil or groundwater contamination. This assessment (screening) should always be carried out for the chemicals in use, the activity in question and in relation to local soil and groundwater conditions.

An overall analysis must be undertaken of the routing of the chemical from when it enters the company until it leaves it again in the form of a product or as solid, liquid or gaseous waste.

When the company and supervising authority need to assess how great a degree of risk a potential source of contamination is posing, it is an advantage for both parties if a standardised decision-making tool is used.

A decision-making tool is presented in the project which includes a number of auxiliary tools divided into the following three main groups:

Risk-based screening of the chemicals in use.
Risk-based screening of the individual activity.
Risk-based screening with regards to soil and groundwater, adjoining areas and to recipients.

With the decision-making tool it is possible to divide the risk into two groups:

Normal risk.
High risk.

Extent of necessary prevention initiatives (barriers)

When it has been assessed whether the activity poses a high or normal risk for soil or groundwater contamination, the company and authority should consider the extent of the prevention initiatives needed, which can be viewed as a number of barriers. The higher the risk, the more barriers are needed to prevent the activity from causing contamination.

A barrier can be passive (e.g. an extra wall around a storage tank) or active (e.g. extra supervision and control).

For activities with normal risk, normal requirements are set. Appropriate additional requirements are set for activities with a high risk of soil or groundwater contamination.

Tank systems with corresponding installations

Within the last fifty years, experience shows that unpressurised tank systems used for storage of chemicals above and below ground level have caused massive soil and groundwater contamination. Of particular note has been the extensive contamination from underground chemical tanks in the chemical industry, as well as from metals and dry-cleaning.

Underground tank systems and pipeline installations have in particular been found to be the source of extensive contamination, as leakages can go undetected for a number of years.

Instances of extensive contamination from above-ground tank systems have also been found. However, these have rarely the same extent as leakages, and are mostly discovered relatively early on.

The project deals with the details of a series of conditions involving metal and plastic storage tank facilities and installations. The installations are important as regards the risk of soil or groundwater contamination posed by the facilities.

Elements which can be included as requirements for tank facilities

Initially, the authorities should make sure that the application documentation accounts for the choice of material and the material’s resistance to influence from the chemical in question. As a minimum, a statement from a specialist on the subject should be made available.

When determining requirements (barriers), these should specify that approval is only valid for the chemicals specified, and that a reassessment must be carried out in the event of any change of use.

The extent of and number of barriers are dependent upon the situation in question and should consider of the age and state of the storage tank facility, level of qualification of staff, etc.

The project gives examples of elements which can be included as requirements for tank facilities. These elements include requirements for construction, establishment, corrosion, protection, monitoring and control.

Impermeable and firm paving and paved areas

In this project, paving is defined as loose or firm materials which are placed on top of the natural soil surface. It follows that a paved area is defined as an area with paving.

In this project, firm paving is a type of paving which, as opposed to loose paving (e.g. gravel), consists of materials fixed together by binding materials (asphalt, concrete, concrete paving) as well as metal plates and polymer membranes.

Basically, loose paving is not impermeable or watertight. Firm paving can be impermeable. In practice, no firm paving is 100% impermeable/watertight if subjected to the influence of liquid chemicals over a long time period.

Impermeable or watertight paving should therefore be considered together with the time period within which the firm paving is subjected to the chemical.

Impermeable paving in this project is therefore firm paving which does not lose its ability to withstand chemical penetration through the paving, over the time it is subject to the effect of the chemicals.

The project deals in detail with a number of conditions involving paving made from asphalt, concrete, tiles and paving stones made from concrete, metal and polymer membranes, which influence the risk posed to the soil and groundwater from the paving types. Apart from the paving types, the project also deals with conditions regarding filling materials.

Elements which can be included as requirements for paving

Elements for requirements can be divided into three groups according to the period of exposure

Short period of exposure.
Medium period of exposure.
Long period of exposure.

The category of the period of exposure depends upon:

Whether or not the paving can be inspected visually,
The slope of the paving (how long a time the chemical may stay on the paving), and
The frequency with which the chemical is handled or decanted.

Requirements for the short period of exposure can be used for paving which can easily be inspected visually. The paving should typically be able to resist chemical influence for a short time span (up to 1 hour) before the exposure is detected and the chemical removed from the paving. Requirements in this group are also used for paving, where any decanting and drawing off of chemicals occurs rarely (up to once a year). The requirements can typically be used for activities such as drainage surfaces at washing areas, drainage surfaces at indoor and outdoor chemical storages as well as at internal transport paths at the company. In most cases, these requirements would be usable for firm paving.

Requirements for the medium period of exposure can be used for paving which can be inspected visually. The paving should be able to resist chemical influence for a medium time span (up to 24 hours) before the exposure is detected and the chemical removed from the paving. The requirements in this group should also be used for paving which are used once a month or less frequently for decanting and drawing off chemicals. The requirements can typically be used for activities such as collection of containers from refilling areas, tank yards as well as certain rarely used filling areas. Dependent upon the conditions at the company, requirements in this group can be used for both firm and impermeable paving.

Requirements for the long period of exposure can be used for paved areas which are complicated to inspect visually, so the paving should be able to resist influence for up to 3 weeks before the exposure is detected and the chemical removed from the paving. The requirements in this group are also used for paving where decanting and drawing off chemicals occurs frequently (up to several times a day). The requirements can typically be used for particularly exposed activities such as filling areas, collecting wells, pipelines or pits as well as under machinery/facilities which are complicated to inspect visually. In most cases, these requirements can be used for impermeable paving.

Chemical storage, washing and filling areas

Spills of chemicals may cause soil or groundwater contamination in chemical storage and in washing and filling areas. These may be indoor or outdoor.

A number of elements for requirements (barriers) for the prevention of soil or groundwater contamination from storage and washing areas are set up which can be used in connection with establishing or renovating existing areas.

The extent and number of barriers (requirements) depend on the actual situation and should be determined with regard to the age and state of the area, the level of qualification of staff, etc.

The project gives examples of elements which can be included as requirements for chemical storage, washing and filling areas. These elements include requirements for facility, operation and design, control and maintenance.

Audits and internal inspections with a focus on prevention

At facilities handling chemicals which can lead to soil and groundwater contamination, it can be advantageous to have the audit conducted by two auditors; one with expertise in business conditions and one with expertise in soil and groundwater contaminations.

As preparation, it can be relevant to collect information about the chemicals used at the company with regard to compound characteristics, usage and location. The supervisor should examine company files and where necessary municipal building or contingency plans for references to any tank systems for storage of chemicals at the facility. The supervisor should also investigate the age of the tanks, the volume, the type of chemicals, the location and the most recent leakage test.

With regards to paving, the supervisor should check whether any material in the files describes which types of paving are present at the different activities which can pose a risk for soil and groundwater contamination at the company.

For use in audits, a number of check lists for the following topics are presented in the project:

Tank facilities.
Paving
Chemical storage areas.
Indoor and outdoor production facilities.

The checklists may help the authorities clarify the operation, quality and internal inspection of the facility.

Internal inspections can be seen as an opportunity for the companies to continuously monitor for spills or leakages. Internal inspection in relation to soil or groundwater contaminations will normally be by monitoring paving, tanks and pipelines.