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An Information Guide to Duck Key in the Florida Keys


 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 Duck Key Wastewater

 

aquaduct authority meeting with Duck key

Pictured above is an image showing the Florida Keys Aquaduct Authority meeting with residents in January at Steve Casey's home on Duck Key.

 

This letter below came to me as an e-mail attachment in Windows' document format. In opening it up in rich text format so that I might paste it to this web page it may have lost paragraphing or formating in the conversion process. - Dick Adler

 
Letter to Florida Keys Aquaduct Authority from Tom Rooney

 

Date: January 31, 2005

 

Thank you for the information we received during our meetings on Jan 24 and Jan 26 and on the email exchanges.

As I understand it you plan to go ahead with a design/build approach for the three utility systems all bundled together.

1. Potable Water Transmission and Distribution System

2. Wastewater Collection System

3. Reclaimed Water System

You outline in the preliminary bidding documents a combined wastewater collection system that has a vacuum system in Center Island and gravity systems on the other three islands that make up the residential islands of Duck Key.

I am concerned about some aspects of this approach and will make recommendations for change.

A. Wastewater Collection System

 

Your position is that the vacuum system is generally economical except for the effect of the 10' elevation of the barrel bridges. These bridges would require an additional vacuum station at each bridge and that cost is $1MM bridge vacuum station. You have dismissed initially the low pressure system because it cannot function in the case of a power outage. Thus you have gone to a combination of the gravity system in three of the four islands of the project (Harbor, Yacht Club and Plantation) and a vacuum system on Center Island..

A gravity system is not suitable for the conditions on the three large islands at Duck Key. It could be suitable for Harbor Island because trenching is in sand. We have hard, fractured, porous rock on the three large islands that make excavation very expensive. The ground water varies with the tide but is between 3' and 4' below the road surface. A pump test would confirm the amount of flow to be expected and that flow would be substantial. Your initial concept was to have the gravity pipe depth limit at 8' max. At this depth the contractor has a high risk even with a pump test and an unknown without one. Besides the cost issue the inconvenience to the residents is an issue. We recommend abandoning this gravity system concept as not economically viable. There is no reason to abandon the potential of the gravity system. Depending on the method of project delivery, the design builder, or the designer will need to make a determination of what system may be more capital cost effective. Perhaps they will land on the vacuum system however, as we have found the costs of the vacuum and pump stations (VPS) to be so expensive, the gravity system may have merit based on capital costs; now along with operational costs.

With up to three potential VPSs in the system because of the existing conditions (mainly bridges) by the way, there is not a VPS proposed at the WWTP), a vacuum system may, or may not be the most cost effective. Also depending on the form of project delivery, perhaps the design build team may find that they can lift vertical 13-feet that would reduce the number of VPS.

I maintain that the marketplace should determine the cost effectiveness of the system; not to arbitrarily abandon an acceptable potential.

The vacuum system will have some pipe below the ground water at the infrequent 5' depth and that will add some expense but nothing like the gravity system. We think this should be studied as a system throughout the islands with a vacuum station in the center of each island but using a force main back to the treatment plant not an additional vacuum station. It is possible to leave Harbor Island on gravity because of the sand. When the nearby residents see a rendering of the Vacuum Stations with a security fence around it and the fact that the generators will be noisy you can expect some feedback. In a vacuum system you have to factor in the acquisition costs, as well as public acceptance of the VPS. We have had major opposition to site acquisitions for utility projects in the near past. In this case, it would be very helpful for the Duck POA residents to be at the vanguard in identifying VPS locations, and prepping the neighbors to dispel the rumors about VPSs.

 

A low pressure collection system should be studied as a possible alternative. At this point we very well may consider its use due to the extremely, often ridiculous high capital costs. In addition, as explained, Duck Key frontages are much greater than typical keys lost hence the amount of pipe per EDU increases by close to 50%, and in Duck Keys case, the development is only about 50% built out. So, in effect, the system will just about need to be constructed for all 700 lots when only about half are being served.

Keep in mind that the monthly operational costs of the grinder system will be much greater, mainly individual pump operation and repair however, if the Duck Key residents don't care, this system does have merit. Also, it would be very helpful for the Duck POA residents to again be at the vanguard in telling residents of the need to provide blanket easements on their property for the operation and maintenance of the grinder systems, and dedicate the area and utilities for the system. These issues will greatly assist in implementing this type of system.

 

3.1

The low pressure system does in fact have some storage capacity in the case of a power outage. Depending on the vendor chosen it can provide up to 100 gal. of storage if you do nothing more than use their standard equipment. With the power out you can't work your dish washer and clothes washer so this should be enough for one days storage per household. In the case of a hurricane where we could be out for a week or so the following would be the situation. The vendor will have provided a plug-in connection for a generator and the owner can hook in if he has one. Alternately additional standby capacity can be economically provided by increasing the size of the service pipe from the house to the pump grinder tank or by adding a plastic tank in that line. The inverts would have to be such that effluent wouldn't store under normal operating conditions. This could be enough to provide storage for a week under the conservation conditions in place after a hurricane. The homeowner can decide to get the additional capacity through a generator or through storage or they may decide to do nothing. Remember only 25% of our residence are in the Keys during the riskier hurricane months. Most of them would leave also when ordered so we are only talking about 30 or so families that would be affected.

 

3.2

Maintenance and operating costs should not be an issue on this system. Typically the electric bill is $25 to $35/year for the pump/grinder unit. The pump grinders often go years without requiring any attention.

One vendor claims their mean time to service a pump grinder unit is 8 years.

The units are light enough for one man to remove it and then replace it himself in an hour. Vendors recommend that the utility own and maintain the units instead of the homeowner.

 

3.3

The initial installed cost of the pump/grinder station is less then $4,000//unit for our quantity. Sometimes they can put two houses on a unit but they only recommend that if the utility owns the pump grinders. The cost of the collections system is where the savings are realized. The pipe will generally be 3' down and above the water table and often without rock.

Because the sewage has been ground the pipes are small. The costs are comparable to a water distribution system as you have a lot of freedom in locating the pipe. They typically lay it with reels of rolled (900') HDPE pipe. Because of the fewer joints in the pressure system compared to the gravity system and vacuum system you have a much tighter line over time.

 

3.4

This system has been around for many years and is proven. It is especially appropriate in hard rock and groundwater conditions. It is installed at Key West Naval Air Station and Sunset Key. It may be a solution for you in other parts of the Keys also.

Summary: I would like to see the total vacuum system and the low pressure system studied conceptually to determine the best solution for Duck Key on the basis of Present Value. Once the best system is determined the project then can go forward with the one system into the design build phase.

 

B. Contracting Methods

You have discussed two methods of proceeding: Design Build Detail Design, Lump Sum Bid and Construct

Before a decision is made on a Design Build concept a survey has to be made to determine how many competent bidders will actually bid the project You may have done this already. The key word here is competent. With the three piping systems the bidder has to do some design to bid it This will limit the number of bidders either because of cost, sophistication or concern about award. If you canít get 4 or so bidders to commit to respond you shouldn't go Design Build. If you only have two bidders you may not really have a competitive situation although you might think you do. If you are assured of competent competitive bidding the Design Build approach is good.

If you can't then you should do a complete design and get competitive Lump Sum bids. You will no doubt get competitive bidding in that second scenario as there are a lot of lump sum contractors for this amount of work.. We are discovering that design build may reduce the amount of bidder/proposer participation. In addition, the process does not appear to expedite the project delivery; in fact it could slow it up. Although we are expediting the City of Layton project through D/B, it is a small project and was actually assisted by having only one Proposer; a unique situation. Because there is some much pipe in this project, the project in my opinion lends itself to a design, bid, and build project delivery. I believe in this case, the number of bidders will increase because of the project volume. Keep in mind that this is low price work, and sometimes low price is what you get.

 

One reason we considered a design build qualifications based project delivery process.

Crawl Key Alternative

You have just opened bids on a major treatment plant on Crawl Key. This plant is correctly located on an island that is sparsely populated.

Conceptually why are we overhauling the Hawks Cay plant for use when all of the sewage (Conch Key, Hawks Cay and Duck Key) can be sent to the Crawl Key plant? Is it not a better use of our collective resources to demolish the Hawks Cay plant, clean it up and use the property for the best available use? I haven't seen the most current operating figures on the Crawl Key plant. If the cost per gallon treated there is comparable to Hawks Cay you should study the concept of pumping the sewage to Crawl Key. The accrued value of the pristine piece of property under the plant should offset the cost of routing the sewer line and the required reuse line to Crawl Key. We need some long term thinking about what is best fore our collective communities. I request a study of the economics of taking the sewerage to Crawl Key and closing the Hawks Cay plant. I believe you just got the economics of going to Crawl Key from the recent Marathon Cost Proposal. It appears that the WWTP costs for that project will be equal or possibly significantly greater than the upgrade to the Hawkís Cay WWTP. Based on the recent equation for the design and build of the Hawkís Cay WWTP upgrade, the unit cost of ~ $10 per treatment gallon has been established. We will receive the itemized costs of the Crawl Key WWTP however, I highly doubt that that the unit cost will rival the Hawkís Cay quote. Also, waiting on the Marathon decision could take a while that could jeopardize the Duck Key in the Hawks Cay option.

I write this memo as a resident of Plantation Island of Duck Key not on behalf of any organization. I am concerned about future sewer costs, unnecessary excessive interruption in life style and government waste.

I would appreciate a response as soon as practical.

Best regards,

 

Tom Rooney

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