City of Waterloo Pond 53 Stormwater Management Pilot

The City of Waterloo plans to remove over 30,000 m3 of accumulated sediment in its Silver Lake stormwater management (SWM) facility. Against standard practice, however, the City will not accept the sediment at any of its landfills due to diminishing capacity. In order to better manage its stormwater facilities, as well as investigate viable forms of sediment reuse, the City will pilot a pond redesign with new sediment treatments on a smaller SWM site, as well as perform field growth tests of the sediment. The City’s Official and Asset Management Plans both speak to SWM and the need to ensure that both water quality and quantity controls are in place to meet regulatory standards. The first stage of the pilot will remove 3,000 m3 of accumulated sediment from the Laurel Creek SWM Area (Pond 53), which lies upstream of Silver Lake. Application of a product called Soil Lynx® will bind the sediment, which will cause the total dissolved solids (TSS) to coagulate, resulting in a reduced time and effort to dewater the sediment. After removal, redesign of the pond’s forebay* and outlet structures will prime the site for the application of the Water Lynx® product in the incoming waterway. This product excites very fine particles to coagulate in the sediment, thus allowing the finer sediment to settle out more precipitously in the forebay over time. The redesign of the pond will also include retrofitted inlet structures and basin length in order to increase detention time of the water flow path. The second stage of the pilot will combine the treated Pond 53 sediment with compost to demonstrate to the Ministry of Environment and Climate Change (MOECC) the growth potential of the sediment in planted road medians and boulevards. Comparison of sediment samples to O. Reg. 153/04 for bulk soil and O. Reg. 347 for leachate parameters will determine if the province approves the reuse of the sediment, or if it still requires landfill. The O. Reg. 153/04 data will combine with a specialized topsoil quality analysis for the purpose of matching the sediment to receiving soils. The combination of increased diversion and trucking of sediment to the landfill will also result in a lower overall carbon footprint of the City’s stormwater management practices. Pond 53’s redesign concept and sediment-binding treatment aims to combine traditional end-of-pipe solutions with newer low-impact development concepts. By increasing the removal of metals and nutrients contained in sediments, the City would remove an increasing concentration of chemicals from the water to protect downstream receivers (i.e. Silver Lake, the Grand River, and Lake Erie). If successful, the pilot will result in an increased reduction of TSS of 97%. Upon construction completion, the City will model the TSS removal rate to other city-owned SWM facilities, including that of Silver Lake’s. The final report will focus on the effectiveness of the binding-products and the beneficial reuse of sediment in terms of cost reduction, increased TSS removal (water quality), and waste diverted from landfills. *A settling basin situated at the inlet of a SWM pond that serves to settle sediment from incoming stormwater before it is delivered to the catchment pond. (Project description from original funding application)