Guest Column: Cudjoe Regional Wastewater System, a Solution?

For almost a year and a half, I have been arguing that the planned, pressurized wastewater system, using grinder pumps, that is proposed for the Cudjoe Regional Wastewater System (CRWS) is uneconomic, unreliable, a burden on homeowners, and a potential environmental nightmare.  Now we learn that the shallow injection well design (120’ deep well) at the treatment plant may be an environmental disaster as well and is probably illegal, if the DEP actually enforces its own regulations.  How did we get to the point; where we are willing to install a system in the fragile environment of the Florida Keys, which may be worse than the septic systems we have now?  The answer is MONEY!!   In the 2006-11 timeframe, when the County and FKAA were being forced by the State and the EPA  to move forward with a sewer system, there were no State funds, the 1% infrastructure tax was to expire in 2018, and estimates for a system serving about 9,000 homes was well over $ 200 million.

What has happened since then?  First, on a technical side, we have learned that the Pressurized System (PS) that is proposed may be the worst environmental option one could choose.  It ranks below just about everything but old septic systems and cess pits.  Why?  Because the FKAA will install hundreds of miles of pressurized plastic pipe underground, with no way of monitoring leaks, and a 100% certainty that leaks will occur and pollute our near shore waters.  We have also learned that after power outages and high load conditions, the starting pressures of a pressurized system can exceed the design and test limits, causing fittings to rupture and sewage to backup into homes.  This is not speculation, it has happened in other systems.

Second, we now know, with certainty, that a Pressurized System has a much higher long term cost than almost any other system.  PS only has a lifespan of 25 years as opposed to a gravity system which can last 60-100 years.   Regular maintenance, generator backups, pump replacements, remote monitoring, flushing requirements and the failure of the many moving parts lead to a maintenance nightmare for homeowners and huge long term cost for all Monroe County citizens since the sewer rates are Countywide.  The grinder pumps selected may not meet all state regulations regarding explosion proof motors and appear to have been approved by the DEP based on a very liberal interpretation of some non-applicable exceptions.

A review of the sewage flow calculations from homes to the treatment plant on Cudjoe Key appear to have used low estimates of flow per home and do not take into account the expected buildout over the next decade.  Why is this important?  First, as the flow requirements increase during peak periods or after power outages, the operating pressures go up significantly, leading to increased failures.  More importantly, the increased design flow means that the proposed shallow injection wells cannot be permitted.  Instead, injection wells of over 2,000 feet must be drilled.  Consider where one to two million gallons of partially treated water will go when it is injected into porous limestone only 120 feet deep.  Independent scientists predict decreased water quality, algae blooms, and a general deterioration in water quality in the Cudjoe Key, Sugarloaf Key and Summerland Key areas.

Finally, there is the legal issue of equality.  Simply stated, the Monroe County Board of County Commissioners decided to convert some subdivisions from grinder to gravity with no real rationale.  The Commissioners simply drew a line on a spread sheet and pronounced the ones below a certain cost to be gravity and those above to be a pressure system.  What was the basis for this decision?  What analysis was done?  Was there a lifecycle study?  Were there other subdivisions not on the list that were below the line?  The decision was made on the fly, by five Commissioners, at a monthly meeting, with no analytical support.  We know there is a section of Lower Sugarloaf that has a lower estimated conversion cost but was not on the spreadsheet and therefore ignored.  No lifecycle analysis has been conducted since 2009 to get the real cost of these systems.  That is interesting since when the bids came in the cost of gravity components were about 29% lower than estimated while the low pressure system was 9% lower.  Further, the LifeCycle analysis performed by Matthews consulting assumed every system has a life of only 20 years.  Without considering different life’s for different systems it was worthless.

What is the solution and how is it paid for?  It has taken me 18 months, the review of thousands of pages of regulations, design documents and construction contracts, input from other engineers, scientists and economists, as well as hours of financial and engineering analysis to reach this point.  Here is the blunt answer:

  1. Get rid of all grinder pumps on individual properties.  About 1,200 of the remaining 1,500 planned grinder pumps are in subdivisions and can be converted to gravity.  The FKAA has stated that they can do it if the BOCC approves the incremental cost of $ 18 million.
  2. Install Septic Tank Effluent Pump (STEP) systems on the remaining 300 properties.  These cost about $ 20,000 per home, of which the homeowner has already contributed $ 4,500 and a bonus is that the EPA pays for 75% of the cost, meaning that the cost of these remote locations will be minimal and reduce the overall cost.
  3. Redesign the lift stations so that they comply with State and Federal code.  Select explosion proof motors that will work within the system. Since there will be no individual grinder pumps, a uniform design can be selected that meets the pressure and flow requirements.  Install Telemetry equipment which will verify flows leaving the lift with those aggregated at the main header or booster pumps.  This will minimize unidentified leaks.
  4. Abandon the shallow injection well at the treatment plant  and install deep injection wells the system requires and our environment deserves.
  5. Minimize the use of temporary injection wells on Big Pine in order to reduce the degradation of the freshwater lens.  This is done by installing gravity lines in wet trenches and by dissipating fresh water pumped from trenches on or near the surface so it returns t the fresh water lens.What will this cost and where does the money come from?
Action Cost per unit

Estimated Total Cost

Conversion of 1,200 grinder pumps to gravity $ 15,000 per unit

$ 18 mil

Convert 300 grinder pumps to STEP Save $ 7,000 per unit

-$ 2.1 mil

Replace 120’ shallow well with  2,000’ deep injection well  Estimate $ 5 -8 mil

$ 8 mil

Total up front construction cost

 Approx $ 25 mil

Where does this money come from?  As I stated earlier, in 2011 there were no secure funds.  Now we have about millions from the state (part of $ 50 mil in 2012 and 2014 awards), an extension of the infrastructure tax that will generate $ 13 million per year in unincorporated Monroe County or almost $ 200 million from 2018 through 2033.  This money can be monetized into bonds.  What will the total cost of a proper system be?  It was estimated to be $ 192 million in May 2012 when the County presented its plan, as required by the DEP.  Based on present commitments, it will now be near that level.

Is the cost to the County really $ 25 million more?  No!  That is the upfront cost only.  A properly performed lifecycle analysis shows that pressurized grinder pump system costs twice as much per home as gravity.  Second, as the system grows, with Little Palm, and general build-out of the lower keys, the 1 MGD inflow will require deeper wells at some point.  So it’s pay now for a proper system or later for a substandard one.

In conclusion, with the plan I propose, the citizens and rate payers in Monroe County get an effective, efficient, reliable and environmentally superior system for a reasonable cost that is paid for out of money that was originally targeted for this very purpose.