Erosion and Sediment Control is the practice of preventing storm water contamination by sediment through controlling the amount of exposed soils during construction. The core to Surrey's strategy to managing this pollutant source is the Erosion and Sediment Control (ESC) By-law that was enacted by Council in March 2007. The ESC By-law sets forth mandatory standards for site ESC planning and the adoption of Best Management Practises during construction.
Potential damage from sediment pollution
Sediment pollution entering storm water degrades both the infrastructure (storm sewers, catch basins and culverts), and the receiving environment. It can cause a wide range of issues such as:
Sediment fills up storm drains and catch basins which increases the potential for flooding.
Cleaning out accumulated sediment from the municipal drainage system burdens taxpayers with a considerable preventable cost.
Sediment in stream beds disrupts the natural food chain by destroying the habitat of small organisms.
Sediment effects fish, it can clog their gills, reduce their resistance to disease, lower growth rates and affect their egg development.
Sediment deposits in rivers can alter the flow of water and reduce water depth.
ESC By-law standards
Best Management Practices (BMPs)
BMPs were always required on construction sites but voluntary compliance was not very high and the builders and developers who were following BMPs were left with higher costs of development.
The ESC Bylaw levels the playing field so that every construction site has to invest in the BMPs. Areas where ESC has been in practice for some time show that BMPs add only 2% to the cost of development.
The ESC By-law specifies that no site can discharge water above 75mg/L Total Suspended Solids (TSS).
TSS must be tested independently in a lab, but the turbidity (cloudiness) of the water can be monitored in the field using a hand held turbidity meter.
A sample measuring greater than 60 Nephelometric Turbidity Units (NTU) is usually the trigger point where the sample must also be sent to the lab for analysis.
ESC Permit requirement
All construction sites require the use of BMPs. You'll also need to apply for an ESC Permit if your site is greater than 2000 square meters (approximately half an acre). Larger sites are more complex and require detailed plans and an ESC Supervisor to ensure that site discharge is managed.