Inflow and Infiltration (I&I)

pano of the Rivanna River January 10, the left side of frame is looking downstream toward Monticello, the right side of frame is the view upstream.

(if the photo is too small there is video)

7. Since 2006, RWSA, the City, and ACSA have worked together to conduct flow studies, analyze flow data, assess wet weather limitations, calibrate a transmission system computer model, forecast future dry weather flows through land development projections and identify inflow and infiltration reduction goals across all sewer collection systems connected to the Facility. The goal of these projects is to assure adequate capacity in the transmission and treatment systems with emphasis on addressing unpermitted discharges. The three entities are working cooperatively to upgrade their respective sewer collection systems.

Sat, Jan 15, 2011 at 5:53 PM To: Council
Cc: tfrederick@rivanna.org

Dear Councilors,

December 8, during RWSA’s presentation on the Rivanna Pumping Station, I asked Mr. Frederick how much it would cost to repair the inflow and infiltration problems that affect our waste water system (by system I meant all waste water pipes that connect to RWSA’s waste-water treatment plants).

As I understood his response, to get to the optimal industry standard practices fix of our waste water system would cost $400 million, this is the fix where there is still I&I but it is substantially reduced. To actually fix the pipes (make them water-tight, no one does this), would cost around two billion dollars.

Rivanna runs a system, hydration and sanitation. Alas, I can’t think of an apt analogy. My not so accurate way of thinking of it…

“It is like a car. The input side, the water supply, is the gas. Water supply speeds up the economy, we can hook up houses, hook up businesses. The safety side, the sanitation, is like the brakes. The waste-water (output) side must collect and treat the effluent from these houses and businesses.”

Our region has spent a great deal of time/money studying the input side. It is my impression that we have spent less time studying the output side. If I understood Mr. Frederick correctly, a detailed study of the waste-water side would take ten years to perform. The RWSA board in the past (2005) approved an evaluation of the waste-water side, but it’s my impression that that evaluation was not equal to a detailed study.

To me, it makes sense to repair the sanitation side in lock-step with increases on the water-supply side, like balancing a budget. Hope this will happen as we move forward.

Does the 25% I&I reduction by 2020 to which we (RWSA, ACSA, CHO Public Works) have committed achieve that balance?

Thanks,

Bill Emory Charlottesville VA 22902

Author: WmX

I stumbled off the track to success in 1968, started chasing shadows that summer. Since then, In addition to farm-laborer and newspaper photographer my occupational incarnations include dishwasher, janitor, retail photo clerk, plumber, HVAC repairman, auto mechanic, CAT scan technologist, computer worker and politico (whatever it takes to buy a camera.) I am on the road to understanding black and white photography.