As usual you are right on the target. The leaking gravity sewer collection
mains act as giant French Drain collectors of ground water, reducing the
recharge while polluting the ground water with ex-filtration at times. Small
diameter STEP systems would not and cost less to install and operate.
Northern California River Watch has been addressing the issue of
infiltration/ ex-filtration in its environmental litigation for many years.
The same problem is occurring in many of the vineyard plantings that have
installed tile or under-drains. These drains quickly drain off the fields
making land that would otherwise be seasonally wet sponge stay relatively
unsaturated. The result is very evident in the increased flashy flooding we
experience in Graton and other parts of the county. Instead of soaking into
the former apple orchards and pastures, the rain water is drained off
quickly. vineyards develop a plow pan and this limitsthe rate of percolation
down into the water table. Quickly draining off the water and limiting the
depth of the sponge means that far less water is retained going into summer.
By late summer when the smaller creeks are drying out, the problem is
further exacerbated by irrigating from wells adjacent to these same creeks.
This agricultural practice of draining off most of the winter flows needs to
be addressed or floods will continue to get worse while summer flows will
continue to drop.
Here’s a letter I just sent to the PD
Richard Dowd, Chair of Santa Rosa’s Board of Public Utilities, was quoted in
a recent article stating, “If we can shut off the infiltration and inflow,
we don’t have to collect it, treat it or dispose of it. The savings could
be substantial.” This was in reference to the many old, leaky pipes that
collect the City’s sewage and send it off for treatment.
For years Russian River Watershed Protection Committee has been requesting
emphasis on pipe repair and replacement rather than continued construction
of expensive infrastructure that increases river discharges. What never
gets mentioned is all the potable rain water that gets wasted when it could
be recharging our aquifers. The article mentions that flows can go as high
as 100 million gallons a day. This is almost seven times higher than normal
and represents wasted potable water supplies.
In light of global warming concerns and many summer flow problems in the
Russian River, this rainwater could provide a heretofore unconsidered and
greatly needed additional water resource.
Furthermore, while Santa Rosa has a good treatment system as compared to
many others, their wastewater still contains many unregulated contaminants
that could be contributing to problems for endangered salmonid species and
drinking water supplies. Fixing leaky pipes should be prioritized over
massive and expensive new infrastructure that would bring direct discharge
to the Russian River at Healdsburg or Forestville.