photo credit:Ben Brill
**** Please add you comments about karst and development (click here) ****
Voids under interchange concern scientists Goldstream Gazette, July 8, 2008 (click here)
Location of cavities
Close up of cavity
New karst cavities exposed by earth moving activity at Spencer Road Interchange. The City's promised karst survey (mid February) still hasn't been released. Bulldozers are excavating and destroying the very area that is to be surveyed to assess sensitivities and geotechnical attributes of what is to be the foundation of the interchange. Concerns have been expressed about building an interchange over an area that is potentially riddled with void spaces.
(Photos taken at the end of May 2008).
What’s interesting about these excavated cavities is the fact that these environments have never been exposed to the atmosphere or to sunlight. All life within these cavities have gleaned their existence from nutrients largely delivered by ground water. This subterranean network is highly sensitive to disturbance and the interchange blasting and excavations will undoubtedly effect the flow of nutrient sources throughout the karst unit. At one of the larger cavities, the soil at the mouth of the opening was saturated. Upon closer examination a salamander was observed moving within this cavity suggesting these relatively moist environments offer ideal habitat for such amphibians.
Rebar mesh over cave entrance
Triangle plate over vertical entrance
It only took 3 days to cut a swath through the forest to create a pathway for the interchange. Trees were cut right up to the cave entrance and a metal rebar mesh was welded over the lateral entrance. The vertical entrance was sealed with a heavy metal door and locked.
Close cut. Large cedar cut approximately 4 metres from rebar mesh entrance. It is suggested by the Karst Mangement handbook for BC that a buffer zone of two tree lengths (80 metres) be left untouched when a cave entrance is identified.
Looking up hill towards the cave
Looking across cave entrance at cut line
Concerns (no longer concerns - damage done) are being raised about the proposed Spencer Interchange that could potentially impact or even destroy the Langford Lake cave and sensitive karst ecosystem. This site displays some of the interesting features of the karst formation and is designed to educate the community of some of its many attributes.
"Karst management in British Columbia has traditionally focused on the
management of caves, particularly with regard to recreational use. In recent
years, however, the focus has expanded to consider the entire karst ecosystem—
both surface and subsurface components. Karst is now recognized as a valuable,
non-renewable resource that can be highly sensitive to disturbance."
The Songhees elder declared that the LLC (Langford Lake Cave) site/cave is a culturally significant place. The site was visited on June 15, 2007. The site visit was attended by two Songhees councillors, a Songhees elder, one Songhees member (transporting the Songhees councillors), two Golder Associates reps, a Songhees archaeology field assistant, and a City of Langford engineer.
"Is this cave worth saving?" by Rick Coles, The Canadian Cave Conservancy chair International interest in Langford Lake Cave Karst formations typically have void spaces creating potential risks to surface structures (Cartoon of karst at proposed interchange)
Visits to site since May 31, 2007