The City of Delta is going to explore additional measures to reduce the risk of landslides for homes along English Bluff Road.
Council recently agreed with an engineering department recommendation that the city undertake a mitigate strategy of upslope private properties between the U.S. Border and Fred Gingell Park.
The inspection will focus on confirmation of utility service connections, roof leaders and swimming pools being connected to the city’s stormwater and sanitary utility system.
Further analysis will also take place on a new cutoff curtain drain system to provide an objective measurement of its effectiveness in mitigating soil instability.
The test section would be incorporated into upcoming watermain replacement works along Graham Drive, the engineering department notes.
The English Bluff area contains a steep escarpment with residential homes situated at the top and bottom of the bluffs.
The area has very steep slopes, which vary from 30-to-45 degrees, including some sections that are nearly vertical.
Over the years, landslides have occurred along the area, which has prompted ongoing concerns from residents, the report states, adding that slope regression will continue to occur due to natural weathering processes and the steepness of the slopes.
The city has had its geotechnical consulting engineer investigate the situation.
The engineering department report also notes that concerns have been heightened this past year with several slides that have occurred above the 70-200 block of English Bluff Road and Graham Drive.
Those instances of slope instability have coincided with or followed very heavy rainfall as well as a significant storm event this September, which deposited more water in a 24-hour period than is normally seen in Delta for the entire month of September.
The slides have generally occurred in the neighbourhood represented by the South Tsawwassen Beach Owners Property Association and a number of questions from those residents were raised about the upslope properties and what can be done to reduce the overall risk of future slope instability.
Another concern by local residents is the overall drainage catchment being directed to outfalls leading from English Bluff Road west, toward the ocean, the report adds.
A letter to area homeowners this fall provided information regarding safe slope practices, including information about changes owners might make to land in sloped areas without knowing how slopes could react.
Homeowners were reminded to keep yard waste off slopes as it kills underlying vegetation and adds weight to the upper portion of a slope.
