TRADER ACTIVITIES AND POLLUTION RISKS .1 Activities and pollution risks – desktop study.1 Activities and pollution risks – desktop study

The first step in assessing pollution risk is to undertake assessment of the risks based on the activities at the industrial estate. It identifies traders’ activities at industrial estates and the likely magnitude of their impact on surface water quality. Key industrial estate activities investigated in detail in this assessment are presented in Table 4.1.

Unless there are specific recorded incidents at the industrial estate suggesting pollution from a specific source, focus should be directed to an assessment of key pollutants that are most likely to be present in surface water runoff at a typical industrial estate (Gromaire et  al. 2001; Davis et  al. 2006; Rule et  al.

2006; EA, 2007; Stein et al. 2007; Napier et al. 2008; Park & Stenstrom, 2008;

McKenzie et al. 2009; Marshales & Viklander, 2011). These are summarised in Table 4.2.

Risk assessments – trader activities and water pollution 55

Table 4.1 Key industrial activities.

Industrial Estate Activities

Key Investigations on Site Vehicle movement Assess traffic density across the site

Identify traders associated with distributing goods, depots and courier-type services

Assess frequency of road sweeping Chemical storage Identify chemical storage areas

Investigate storage procedures and type of chemicals stored Vehicle wash Identify areas of vehicle washing

Assess frequency of washes per trader

Identify if a surface water collection system is in place Identify type of detergents used

Material storage Identify material storage areas

Investigate storage procedures and type of materials stored Operational spills

risk

Identify manufacturing sites

Identify operations related to re-fuelling and pumping of liquids Wastewater

misconnections

Investigate history of sewer misconnections Inspect manholes visually

4.2.2 Prioritisation of risk areas

Prioritisation of the risk areas has been done based on key activities. Based on literature (Davies et al. 2001), a typical (light) industrial estate is a self-contained series of units predominantly non-retail on the perimeter of towns and cities.

The risk of surface water contamination arising from trader activities was prioritised in accordance with the following hierarchy:

• High risk (red): contamination is very likely to occur and requires further investigation on site (possibly including sampling) and further research on substances released via surface water sewer. These areas are usually related to inadequate site management practices on site which affect areas of chemical and material storage and areas of operational spill risks.

Key hot spot areas on industrial estates are storage and service yards, historic contaminated land and any areas with illegal waste disposal and general industrial litter. Chemical/oil spills that can be the result of various industrial activities, for instance dispensing oil, antifreeze, and other potentially hazardous liquids, can result in spills and leaks around the dispensing area. Another area focused on was leakage or spillage occurring around tanks from filling, dispensing, and deterioration of pipe connections or failure of secondary containment. Sewer misconnections are considered high risk of contamination with raw sewage and the possibility of blockages in the surface water drainage network and related risk of localised flooding.

• Medium risk (amber): contamination is likely to occur. Traders’ operations and other site activities identified as having medium risk need to be checked on site and further reference literature data need to be gathered to assess the requirement for treatment by SUDS. These areas include mainly car parks and roads. Key activities that bring attention to possible surface Table 4.2 Key surface water pollutants and their sources.

Pollutant/

Indicator

Sources at Industrial Estates

BOD and COD Organic matter disposed via waste disposal and recycling centres Possible release of toxic leachate via surface water drainage Organic matter associated with solids washed off impermeable surface areas during a rain event

Corrosion Inhibitors used at manufacturing sites TSS (Total

Suspended Solids)

Road runoff

Runoff from impermeable surfaces, including roads, car parks, service & storage yards

Car washing & maintenance Equipment or vehicles stored outside Vehicle repair/brake shoe replacement

Material storage: stripping metal or wood surfaces outdoors Atmospheric deposition

Storage of general waste or food waste outside in dumpsters Total Heavy

Metals, mainly zinc, copper, lead

As above for sources of TSS as most metals are associated with solids

Exposed copper/galvanised piping, galvanised building sidings/

roofing, or exposed copper, brass, or zinc coated materials exposed to stormwater

Car washing & maintenance

Vehicle repair/brake shoe replacement

Material storage: stripping metal or wood surfaces outdoors Replacement or storage of lead/acid or nickel/cadmium batteries or long time storage of vehicles or powered equipment outside PAHs (Polycyclic

Aromatic Hydrocarbons)

Equipment or vehicles stored outside

Car washing (two sources: (i) cleaners containing mineral spirits/oil or petroleum products, (ii) washing off lubricating oils and dust) Vehicle maintenance, equipment maintenance, involving grease Parts & equipment cleaning outdoors

Oil (& other fluids) dispensing & outside storage Wrecked or damaged vehicle storage

Pumping liquids from storage tanks into site buildings or into vehicles

Ammonia Storage of general waste or food waste outside in dumpsters Organic matter disposed via waste disposal and recycling centres

Possible release of toxic leachate via surface water drainage

Risk assessments – trader activities and water pollution 57 water pollution are ad hoc uncontrolled car washing, vehicle movement and impermeable surface runoff during a storm event.

• Low risk (green): contamination is not likely to cause concern; no further investigation is required. Usually these areas are associated with roofs and building sidings (depending on the type of materials and age, these could be considered as medium risk) and landscape areas. Site management activities such as cleaning of road sides, gully pots, existing interceptors, regular removal of litter, preservation of landscape areas and general aesthetics of the site area are all indicators of how well the site is managed. Additionally, storage and service yards of well-managed traders that can give rise to some residual diffuse pollution are considered low-risk areas.

4.2.3 Verification through site visits

The desktop analyses were verified through site visits. The site visits focused generally on high risk areas and the locations with ‘atypical’ characteristics were identified (Figure 4.1).

Figure 4.1 Pollution risk areas and activities.

Maps of the industrial estates (Figure 4.2) were produced for each site marking clearly the areas based on risk of pollution. These areas would require additional pollution control measures to reduce their ‘a typicality’ and normalise the sites into the typical (light) industrial estates category. Very often the site visits revealed high risk areas in places that were not previously identified by the desk-top study.

Figure 4.2, represents a typical situation, but is for illustrative purpose only and does not identify the actual trader risks or contributions.

Figure 4.2 Pollution risk areas across the industrial estate.