FKAA adds generator input for grindersBy Steve Estes
One of the primary arguments against the extensive use of low-pressure grinder pumps in the Cudjoe Regional Wastewater System is the all-too-frequent occurrences of extended power outages.
Even without a hurricane blasting its way through the Keys, which hasn’t happened for seven years now, power outages here are more frequent than in many places around the country.
And those who don’t feel low-pressure grinder pumps will provide the best performance for the dollar argue that while the reported two-day storage capacity of the pump holding tank will get them through the short outages that happen with regularity, the longer outages that are caused by storms might wind up being a mess for homeowners who have the grinder pump systems in their yards.
“We have a few different ways to handle that situation,” said Don Hubb, assistant engineering director for the Florida Keys Aqueduct Authority.
The FKAA is the entity responsible for overseeing construction of the Cudjoe Regional and then for operating and maintaining the system when it comes on line.
The Monroe Board of County Commissioners is the entity charged with paying for the construction of the system and makes decisions about what areas are serviced by the central collection system and what areas are serviced by upgraded on-site treatment plants. The BOCC also had to approve the eventual designs for the Cudjoe Regional system, which includes just under 2,800 grinder pumps, with about half of those to be on Big Pine Key.
Some Cudjoe Key residents have already begun to question the decision to include so many grinder pumps in the system design, and community meetings for the outer islands portion of that system, Lower Sugarloaf and Ramrod through Big Pine Key, have just begun, whereupon property owners in those areas will learn if they’re in low-pressure areas..
Until the final design is in place, not all of the properties that will use low-pressure pumps will be known, but the final numbers are pretty solid, said Hubb.
Construction has already started on the inner islands portion of the system which includes Upper Sugarloaf, Cudjoe and Ramrod Keys.
According to Hubb, some of the homes affected will have whole house generators that kick in during times of power outage, “and these pumps will run on those, particularly if folks turn off some of the higher usage items.”
Homeowners who will be using low-pressure systems will have to supply a dedicated 220-volt, 30-amp power circuit to which the grinder pumps can be hooked.
Hubb says that the homeowner only has to supply the power line.
“Beyond that, FKAA’s contractors will supply and install the box that will eventually power the system,” said Hubb.
As part of that box, the contractors will be installing an input, similar to a marine power outlet, that will allow the homeowner to plug their own portable generator into the system and drain the tank.
“We will be providing a 30-amp generator input as part of the power panel that we will install,” said Hubb. “FKAA will be responsible for the power panel, all we need is the power supply from the homeowner’s electrical system.”
“It doesn’t take a lot of power to operate these pumps,” said Hubb. “Almost any portable generator capable of producing 220-volt power can be used if we have an extended power outage, as long as the homeowner has the right plug.”
When the power goes out, he added, an internal switch in the panel will allow for generator input, and when the power returns,the switch will transfer house power back to the unit.
Hubb also said that during storms, when extended power outages may be expected, FKAA will have crews on the road as soon as the storm allows.
“We will have two trucks with full crews and a generator that travel through the neighborhoods where low-pressure pumps are located to fire up those pumps and drain those tanks,” said Hubb.
He said that the crews should be able to drain 50 units per day each, or about 100 total.
“When they finish all the areas,they’ll start over again as long as the power is out,” he added.
While 200 units per day doesn’t seem like a lot, Hubb said, the time after a storm is usually one where many fewer people are home.
“If people evacuate in a major storm, draining the tank will not become an issue,” said Hubb. “There will be no usage.”
He said FKAA officials estimate that less than 60 percent of the homeowners in the Keys will be in the county during hurricane season.
“We expect about two-thirds of those people to evacuate and not need power for the pump. Of the remaining people, not all of them will be on the low-pressure system. We think two dedicated crews will be able to handle the load,” said Hubb.
The properties on gravity pipes won’t have any issues with power, he said.
“There really is no excess storage capacity in the gravity system during a storm,” Hubb said. “It will fill up faster than the low-pressure system because all the street drains go into the gravity pipes. If it floods, the water goes into the gravity pipes.”
He said that the typical low-pressure system will have about two days worth of storage before the pump needs to be kicked in.
“The power may come back on, or our crews will reach that neighborhood,” said Hubb.
“We have tried to build as many fail-safes into the system as possible,” he added.
Regardless of the method used to drain the pumps, it takes about 10 minutes per, he said.
“If things get really bad, we do have mutual aid agreements with other utilities where we can draw manpower and equipment to help us out,” said Hubb.
To address the overflow issue with gravity pipes, Hubb said that each lift station, the only part of the system that needs power, will have an individual generator stored on site and as soon as the roads are passable, FKAA crews will be out to fire up those generators and keep the gravity system flowing to the plant.
“The gravity system cannot affect the low-pressure with the back-flow preventers that will be installed,” said Hubb.
Hubb said FKAA is also planning to go back to the BOCC soon and ask for some additional funding to install remote telemetry units on each grinder pump system.
“We want to know if a unit isn’t working properly so we can dispatch a crew as soon as possible,” he said.
The telemetry units will send a signal to a satellite relay, which will in turn notify the company supplying the units who will then seek dispatch for an FKAA crew.
“It’s our intention to prevent sewage spills into the homes,” said Hubb.