The Cascumpec Bay Watershed Association (CBWA) has added a portable cofferdam to its fish habitat enhancement tool chest.
Association co-ordinator John Lane said the device can be used to temporarily block water-flow in a stream and divert the flow downstream so that workers can adhere to Department of Fisheries and Oceans regulations and perform necessary work in a dry section of stream bed.
The portable dam is light enough that it can be carried to even remote sites by two workers. It can be deployed in 15 to 20 minutes to 20 metres in length and can hold water up to 70 centimetres in depth. The diverter unit, made up of two lengths of polyethylene tubing, totalling 45 metres, will allow up to 5,400 litres of water to be diverted around the worksite per minute. It was purchased with funds from CBWA fundraisers, Government of P.E.I. contributions and supporter donations.
"The cofferdam is a great tool for facilitating doing work in the stream that require the work to be done without water flowing through the stream bed. I was surprised at the efficiency and effectiveness of the cofferdam in being deployed, damming the water, and releasing the water back down stream when the work was completed," said field supervisor for the CBWA, Grace Rayner.
Lane said the cofferdam has already proven useful in various CBWA projects, including installing a silt trap, start-to-finish, in Kildare River in just one day. Workers also used the device to dam a section of the Huntley River so that a silt trap could be emptied.
“The Huntley River silt trap is one of our most efficient silt traps for removing silt from the waterway,” Lane said. First excavated in 2016, this year workers estimate they removed another 550 cubic metres of material from the trap, the equivalent of more than 50 tandem truckloads.