Sewer is no solution for bluffs | LETTER TO THE EDITOR
February 21, 2011 · 8:53 AM
To the editor:
The potential of a sewer on Edgecliff is yet again being raised to “cure” a critical-area development plan.
A tired hypothesis is that it would relieve the pressure of septic-produced groundwater that makes its way to the bluff, so once constructed it would justify higher development densities above Edgecliff Drive. Channeling away any subsurface water is good in theory, but let’s get real about what percent of all bluff-bound water (septic plus stormwater) the septic drainfield outflows represent.
It’s not a big math problem. Let’s look at all water in the most seriously discussed and potentially threatened basin that funnels under Edgecliff. Ten properties’ septics now contribute to its groundwater flow. Taking into account such numbers as the basin’s 430 acres, its 25 drainage-area inhabitants at 100 gallons/day output, nature’s 33 inches/year rainfall converted to gallons, and the approximately 62-percent rate of non-evaporating ground absorption hitting underground downsloped clay layers, and we calculate the percentage of all bluff-bound underground flow to be .24 percent attributable to drainfields. (Want the calculations? I’ve got them.)
So we have just one quarter of a percent of the groundwater in that highly critical basin removed by a sewer! Worse yet is that under city code it would take many years to realize even this effect, since property owners are only required to hook up under limited circumstances, like new owners or septic failure. This low percentage suggests that investment in an adequate stormwater collection and conveyance system along Edgecliff Drive would be a much better bang for our limited taxpayer bucks.
I say the Edgecliff sewer “silver bullet” is a red-herring solution to the bigger issues of critical area development and its effect on Langley’s precious Edgecliff bluffs.