Yearly average of freshwater consumption for Appledore

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Yearly average of freshwater consumption for
Appledore
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Freshwater System There is a 20 foot dug well
that is under the influence of surface water.
This well supplies the island with its
freshwater. All freshwater is chlorinated to meet
the State of Maine drinking water regulations.
The well water is pumped into an underground
holding tank (cistern). From the cistern the
water is then pumped into a steel tank that is
pressurized.
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Note Under high freshwater demands a Reverse
Osmosis Unit (R/O) is used to desalinate
seawater to meet the higher demand. When the R/O
is in use it dumps its freshwater product into
the cistern for use to the island. (More
details later)
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Another potential freshwater source is from
direct collection of rainwater.
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Average rainfall data for Appledore Island May
2.5 in/month June 3.0 in/month July 3.4
in/month Three month average 3 in/month
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Compute rainfall collection area to meet
freshwater demand. Assume freshwater demand
1700 gal/day (blackwater currently uses seawater
source) Conversion units 1 acre 43,560
ft2 1 gallon 0.134 ft3 Water demand
227 ft3/day
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Rainfall intensity 3 in/mon. 0.1in./day
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• Complicating factors
• Need storage for leveling demand with
  rainfall.
• Need to account for evaporation.
• Need to treat for possible contamination,
• (gull droppings, dirt blown into collection
  basin, etc.).
• 4. Need to disinfect.

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Storage considerations Assume dry period 1
month Storage required
A tank 20x 20x 20 would satisfy this storage
requirement