Joined: July 2004
||Posted: 01 July 2008,21:59
Many of the better manufacturers are providing some form of training to interested contractors, which is all well and good, but does not address the problems of ...
1) is concrete block permeable paving really the best option for any given project?
2) is the generic specification promoted by each of the manufacturers actually suitable for every given project?
As block manufacturers, they are obviously keen to see CBPP installed as widely as possible, and certainly in preference to PIC, bitmac, resin, etc., but the key issue of the proposed action should be sustainability of the drainage, and not whether the surfacing is permeable or not. CBPP is being promoted as the answer, but it is the answer to a different question. As long as surface water is disposed of in accordance with the principles of SUDS, it really doesn't/shouldn't matter what surface/paving has been installed. Along with training lads how to lay CBPP, we should be training them to install soakaways, swales and rain gardens, but the training group is too busy pondering its own navel and the opportunity is being lost.
Secondly: the use of generic designs. These are used because the manufacturers need to offer contractors a simple 'design' that they can use on the majority of residential projects. Although we might not want to admit it, the paving trade isn't overpopulated with mathematicians, engineers or structural designers, and it's unrealistic to expect all contractors to be able to do the sums regarding soil permeability, run-off, storage capacity, etc. Hence the generic design: a spec that works for most drives, on most houses, in most parts of the country, most of the time, mostly.
To achieve this, the design has to be over-engineered, as too much capacity isn't a problem, whereas too little would lead to surcharging and/or flooding. Consequently, most of the 'off-the-shelf' specs being offered by manufacturers tend to be OTT. This results in additional (possibly unnecessary) excavation, plus the associated cart away, plus the extra clean aggs to build-up levels, all of which bumps up the cost, but we can't be sure it is actually warranted on any particular job because we are not training enough contractors to do the (very basic) sums that are needed to create site-specific designs. Again, this should have been addressed by the training group months ago, but wasn't, and probably won't be until after the proposed nonsense is enacted. I think that's what they call shutting the stable door after the horse has bolted.
So, the manufacturers don't see the imposition of this proposal as a threat to their business, but as an opportunity to replace some of their low-cost/low-profit standard paving with higher-cost/higher profit permeable paving blocks. That's why you don't hear *any* of them speaking up for SUDS paving rather than permeable paving.
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