PEAT and PARKS

Technically, the area where Cadboro Bay Gyro Park sits is known as a wetland fen. A fen is composed of water and decayed plant material primarily from various kinds of sedges and reeds.

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A fen takes thousands of years to develop and is characterized by a water table that is fed by ground water, fluctuates during the year, is rarely totally dry and is rarely totally flooded.

The Cadboro Bay Fen contains (very approximately) 3 million to 7 million cubic feet of peat. It was “topped up” around 1954 by about 500,000 cubic feet of bark chips and sawdust from the Victoria wood mills.

The area was once home to many kinds of fish and molluscs and there was an estuary where Todd Creek entered the ocean. Salmon came up Bowker Creek to spawn in the region where Bowker and Todd connected and the fry returned to the ocean via Todd Creek and the estuary.

The nature of a fen makes the kinds of development common to parks difficult and expensive. Peat is very useful as a carbon store and is quite fertile, but it is compressible. A living fen constantly renews itself. An exposed fen oxidizes and release carbon dioxide. A fen covered in hog fuel and grass acts unpredictably. If a fen is drained it can be farmed, but then it begins to subside and needs to be drained yet again or allowed to retain to its natural state.

At the moment, while speaking in a Green fashion of restoring wetlands, Saanich in these plans is treating this area as though it were entirely composed of the normal classes of soil (silt, sand, clay and humus) and therefore could be managed as those kinds of soil are: paved, moved, excavated, built-upon, forested, bermed, swaled and grassed. The municipality is also using peat’s capacity to absorb water as part of its arsenal to deal with the surface water common to the rain forest environment of Vancouver Island during the winter months. These two functional goals are at cross purposes.

One major requirement of Park users is to have the park dry enough to be used year round. All three variations of the current plan assume that this will happen and that raised asphalt paths can be built to provide wheel chair access and parking can be improved/created such that it is maintenance free and playgrounds can be “raised” to be useful year round. However, residents have not been provided with the hydrogeological studies which would explain how this all would happen.

There are some fundamental and unanswered questions.

    1. How much peat is there?
    2. What is its condition?
    3. How much ground water flows into this body of peat during the winter months?
    4. What is the annual growth rate of that winter ground water flow given proposed development of the village centre and surrounding area?
    5. What are the targets for the level of ground water in the park at various times of the year?
    6. For how many months will the ground water be at or above the surface level.
    7. Where will the large pumps be that will manage the water table? How much will they cost?

In many places in these plans, the word “raised” is used, whether for paths, parking, buildings or playgrounds. But how will this take place? If the load has a SG > 1, it will sink into the original surface of the fen. Example: the “raised” pathway and rock wall near the octopus from earlier renovations. These have subsided as one would expect for heavy objects imposed on a peat-based wetland.

Consultation on future planning for improvements to this park requires answers to all the fundamental questions raised above.

An active Fen with the harvest of sedge hay.

SedgeCutting

Harvested Sedge Hay in Part of the Cadboro Bay Fen in 1941

UCC farm pic--tweaked

 

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