Appendix 7.33

There is risk from leaks and spillages resulting from bulk storage of chemicals on site. All storage tanks and storage areas for environmentally hazardous substances must be sited on an impervious base and surrounded with a sealed bund wall. The bunded area should be large enough to hold 110% of the contents should a large spillage occur.

There should be no drainage point within the bund wall and any overflow pipes / inlet valves should be contained within the wall. The wall itself should be treated with a chemical resistant coating.

Rainwater accumulating within the bund wall should be frequently pumped out- although it is advisable that all storage areas are roofed.

Solvents should always be well sealed and stored out of direct sunlight and in well ventilated areas. All chemical containers (including drums) should be stored upon drip trays when they are in use in order to prevent pollution of the drainage system.

Water pollution can be caused by vandalism and therefore all chemical and oil storage areas should be well secured for example-through: fitting lockable valves to tanks, securing fences and doors.

Cleaning through the use of cleaning agents and the resultant contaminated water, can cause water pollution if the following is not observed:

• Washing and cleaning of yards and machinery etc. should be undertaken in areas that drain directly to foul sewer- all discharges to foul sewer, however, must be with the consent of the local water company. Permission must always be sought when discharging a substance to sewer that is not listed within the company s discharge consent as the company may face large fines.
• Some sites have installed recycling systems for cleaning water, where it is treated and then reused.
• Sites where there is a relatively large amount of oil storage and use, would be wise to have oil water separators fitted on surface water drains in order to prevent oil being discharged to local waterways. Separators should be regularly maintained, cleaned and inspected. They become useless if polluted by detergents, degreasers or soluble oils.