FANDOM


Water sources at the MLK site community garden of the Carrboro Community Gardening Coalition are being investigated. Water Harvesting information can be found here.

See Also:

Water CatchmentEdit

Water catchment is CCGC's primary source for water. Our backup is well water. Water is collected off of both shed roofs. There are two gutters on each shed, one for each roof pitch for a total of 4 gutters. A rain barrel catches water from each gutter. Each rain-barrel can be linked with a hose for gravity feed to either 275 gal. cisterns or the 1500 gal. cistern also located at the sheds. Water stored in these cisterns is pumped to the garden cisterns using a battery powered pump.

How to use the Battery powered pump for pumping from shed cisterns to garden cisternEdit

  1. The battery powered pump is on a dolly for easy transport to cisterns that need to get pumped.
  2. Connect the inlet hose (see arrows on the woodwork) to tank from which water will be drawn.
  3. Using an extension hose, connect the outlet to the black pipe (goes to gardens) found on the fence at the northwest corner by the northwest shed. You may need a double female adapter (file cabinet). Open valve and make sure second valve on 'Y' is closed.
  4. Check to make sure all appropriate valves are open/closed
    1. On cistern to be drawn from make sure:
      1. main valve (red big one) is open and
      2. also leg of smaller ‘y’ valve to which pump inlet hose should be connected is also open.
    2. At ‘y’ by the CCGC garden cistern. (valve turned for pumping either to the CCGC cistern or the OCPYC cistern)
      1. For CCGC:
        1. place hose end into garden cistern by loosening the cover (key is in shed, but not usually necessary) and dangling the hose in (Remember to replace the cover to keep out mosquito larvae.) or,
        2. Fill garden garbage cans.
      2. For OCPYC:
  5. Turn pump switch on.
    1. Check to make sure pumping is happening by opening the unused ‘y’ valve leg of black pipe switch.
    2. If pumping is not happening:
      1. check lines for kinks,
      2. check valves to make sure appropriate ones are open/closed,
      3. check wiring to the battery, or
      4. recharge the battery.
    3. Do not let pump run dry.
  6. After transferring of water, reverse the above process making sure that all valves are shut except for between gutter catchment and storage beneath the sheds.
  7. Put dolly pump and connecting hoses and adaptors away.

How to use the Battery powered pump for pumping from cisterns to garden bedsEdit

The battery powered pump can also be used to water the garden by hose, rather than carrying water in 1 gallon containers. The procedure is simple and will help avoid under-watering.

A. From cisterns at the shed.

  1. Use the procedure above, except place a long hose from the shed on the exit 'Y' near the CCGC cistern and water as from a garden hose. You may also attach the black 'soaker' hose to the line to water whole beds at once.

B. From cisterns in the garden.

  1. The battery powered pump is on a dolly for easy transport to the garden cistern.
  2. Connect the inlet hose (see arrows on the woodwork) to tank as above.
  3. Connect the outlet to an extension hose, open the valves on the tank.
  4. Turn on pump and pump to beds as with a garden hose (see above for procedures and troubleshooting).
  5. When finished, close valves and return pump and hoses to shed.

Meeting MinutesEdit

StatusEdit

  • The town has given us permission to harvest water from both shed roofs.
  • Plans for doing this should be submitted for review to Parks & Rec (Carrboro) before implementation.
  • 3/4 of the gutters are already up, we are poised to install the rest of the system.

Water Harvesting FactsEdit

  • Surface area and rain: 1" rainfall on 1,000 sq ft. roof produces 625 gallons of water.

rainwater catchment coupled with the use of the well will produce ample supply for the garden.

  • Catchment efficiency: 80% of water in an area can be captured.

Carrboro Historic Rainwater AveragesEdit

AnnualEdit

47.6" Average. During 2007 Drought year we were at 80% of average rainfall. http://www.nws.noaa.gov/oh/hic/current/drought/rah.htm

QuarterlyEdit

  • Summer: June, July, August, : 12.9"
  • Fall: September, October, November, : 10.3"
  • Winter: December, January, February: 11.1"
  • Spring: March, April, May: 12.2"

Available Surface AreasEdit

North ShedEdit

  • West Roof: 404 Feet sq.
  • East Roof: 425 Feet sq.

South ShedEdit

  • West Roof: 432 Feet sq.
  • East Roof: 432 Feet sq.

Ideal Storage CapacityEdit

A simple method of roughly estimating storage capacity popular among professional installers is to size the storage capacity to meet quarterly demand. The system is sized to meet estimated demand for a three-month period without rain.

Garden DemandEdit

The general recommendation is to supply 1" of water per week to a garden. Depending on the weather conditions and the crops being grown, the garden may need 1.5" per week. It takes 625 gallons of water on 1000 sq.ft. to equal 1" of rain.

OCPYCEdit

  • Garden Area: 2400 sq.ft.,
  • Planting area: 1200 sq.ft.
  • Estimate of water needs: 750-1100 gallons per week.
  • 22% of aggregate planted CCGC + OCPYC.

CCGCEdit

  • Fenced in area: 8,611 sq.ft.
  • Planting area: 4,305 sq.ft. .
  • Estimate of water needs: 2,690 gal. - 4,035 per week.
  • 78% of aggregate planted CCGC + OCPYC

CCGC + OCPYCEdit

Because CCGC and OCPYC are sharing watering sources calculating demand of both is useful.

  • Planting area: 1200 + 4305 = 5,505 sq.ft
  • 3,440 gal./week - 5,135 gal./week or 13,760 gal./season - 20,500 gal./season
  • Assuming Planting area is constant throughout the year, per three month period garden demand:
    • 3,440 gal./week x 12 weeks/3 months = 13,760 gal./season
    • 5,135 gal./week x 12 weeks/3 months = 20,500 gal./season


SupplyEdit

WellEdit

Approximately 1,000 gal./ week

Water CatchmentEdit

Water catchment water will be prioritized over well water for watering the garden.

North ShedEdit

West RoofEdit

404 sq. ft.

  • For 1": Gallons per sq. ft. of area:: 404 feet sq. x .625 (gal./sq.foot) = 252.5.
  • Efficiency Factor: = 252.5 gal x .8 = 202 gal.
  • Harvest:
    • Summer: 12.9" x 202 gal. = 2,606 gal.
    • Fall: 10.3" x 202 gal. = 2080 gal.
    • Winter: 11.1" x 202 gal. = 2,242 gal.
    • Spring: 12.2" x 202 gal. = 2,464 gal.
  • Volume from rain on planted garden area (OCPYC + CCGC) per season:
    • Summer: 12.9" x (625 gal./1"/ 1000 sq.ft.) x 5505 sq.ft. 202 gal. = 44,384 gal.
    • Fall: 10.3" x 202 gal. = 2080 gal.
    • Winter: 11.1" x 202 gal. = 2,242 gal.
    • Spring: 12.2" x 202 gal. = 2,464 gal.
North Shed Quarterly Supply in normal average rainfall year
Month Garden Demand Irrigation Demand (GD not Rain or Well) Q Avg. Rainfall (inches) Rainfall collected (gallons) End-of-Season storage
Summer 3,760 gal. -- 20,500 gal. (20,500 gal.) - ( 3,440 gal. x 12.9") = -44,343 + 20,500 = -23,843 12.9" 2,606 ID - 2,606
Fall GD ID 10.3" 2,080 ID - 2080
Winter GD ID 11.1" 2,242 ID - 2,242
Spring GD ID 12.2" 2,464 ID - 2,464
  • Harvest during drought:
    • Summer: 10.32" x 202 gal. = 2,084 gal.
    • Fall: 8.24" x 202 gal. = 1,664 gal.
    • Winter: 8.88" x 202 gal. = 1,794 gal.
    • Spring: 9.8" x 202 gal. = 1,980 gal.
  • Volume from rain on planted garden area (OCPYC + CCGC) per season (during 2007 drought year):
    • Summer: 10.32" x (625 gal./1"/ 1000 sq.ft.) x 5505 sq.ft. = 35,475 gal.
    • Fall: 8.24" x 202 gal. = 2080 gal.
    • Winter: 8.88" x 202 gal. = 2,242 gal.
    • Spring: 9.8" x 202 gal. = 2,464 gal.
North Shed Quarterly Supply during 2007 Drought year
Month Garden Demand Irrigation Demand (GD not Rain or Well) Q Avg. Rainfall (inches) Rainfall collected (gallons) End-of-Season storage
Summer 3,760 gal. -- 20,500 gal. (20,500 gal.) - ( 3,440 gal. x 10.32") = -44,343 + 20,500 = -23,843 12.9" 2,606 ID - 2,606
Fall GD ID 10.3" 2,080 ID - 2080
Winter GD ID 11.1" 2,242 ID - 2,242
Spring GD ID 12.2" 2,464 ID - 2,464
East RoofEdit

425 sq. ft.

  • For 1": Gallons per sq. ft. of area:: 425 feet sq. x .625 (gal./sq.foot) = 266.
  • Efficiency Factor: = 266 gal x .8 = 213 gal.
  • Harvest:
    • Summer: 12.9" x 213 gal. = 2,748 gal.
    • Fall: 10.3" x 213 gal. = 2,194 gal.
    • Winter: 11.1" x 213 gal. = 2,364 gal.
    • Spring: 12.2" x 213 gal. = 2,599 gal.
North Shed Quarterly Supply
Month Garden Demand Irrigation Demand (GD not Rain or Well) Q Avg. Rainfall (inches) Rainfall collected (gallons) End-of-Season storage
Summer GD ID 12.9" 2,748 ID - 2,748
Fall GD ID 10.3" 2,194 ID - 2,194
Winter GD ID 11.1" 2,364 ID - 2,364
Spring GD ID 12.2" 2,599 ID - 2,599

South ShedEdit

West RoofEdit

432 sq. ft.

  • For 1": Gallons per sq. ft. of area:: 432 feet sq. x .625 (gal./sq.foot) = 270.
  • Efficiency Factor: = 270 gal x .8 = 216 gal.
  • Harvest:
    • Summer: 12.9" x 216 gal. = 2,786 gal.
    • Fall: 10.3" x 216 gal. = 2,225 gal.
    • Winter: 11.1" x 216 gal. = 2,398 gal.
    • Spring: 12.2" x 216 gal. = 2,635 gal.
North Shed Quarterly Supply
Month Garden Demand Irrigation Demand (GD not Rain or Well) Q Avg. Rainfall (inches) Rainfall collected (gallons) End-of-Season storage
Summer GD ID 12.9" 2,786 ID - 2,786
Fall GD ID 10.3" 2,225 ID - 2,225
Winter GD ID 11.1" 2,398 ID - 2,398
Spring GD ID 12.2" 2,635 ID - 2,635


East RoofEdit

Same area as South shed's West roof

Solar Pump DesignEdit

SolarPump

Mobile solar hand-cart water pump design by Dave Delvechio

A simple mobile solar powered bilge pump will move the water from the water catchment site to the main garden cistern and can also be used to pressurize and move the water from the main garden cistern to the garden.

Gravity DesignEdit

  1. Takes advantage of the fact that water is captured from raised shed roofs to transport water to garden using gravity.
  2. Height is maximized by placing barrels:
    1. immediately below the gutters.
    2. Placing them Horizontally
  3. Barrels are interconnected with tubes coming to the lowest point of each barrel. Interconnectivity effectively provides cistern function.
  4. Raised storage water barrel structure has alternative trellis function.

North ShedEdit

West HalfEdit

  • Barrels:
    • Radius = 1'
    • Height = 3.33'
    • Volume/barrel = 10.5 cubic feet = 78.5 Gallons
  • Total Capacity:
    • Total Volume(x10) = 785 Gallons
  • Bearing Weight:
    • Weight of water/barrel = 8.33 lbs./Gallon x 78.5 Gallons = 654 lbs.
    • Weight of Water & Barrel/barrel = 654 lbs. + Barrel weight
    • Total weight: 10 barrels x 654 lbs. = 6,540 lbs.
    • Weight per 4x4 column: 6,540 lbs. /13 = 503 lbs.
  • Garden Distance
    • 135' to water cans
    • 170' to closest fence post

WaterCatchment

Needs:

  • Barrels: 10 (R = 1', L = 3.33') 78.5 gal.
  • Treated Lumber
    • 6 (4" x 4" x 5') if can use existing shed posts
    • 3 (4" x 4" x 4.75')
    • 2 (2" x 6" x 3.75')
    • 1 (2" x 6" x 4.8')
    • 1 (2" x 10' x 4.2')
    • 1 (2" x 10' x 4.7')
    • 4 (2" x 6" x 4.7')
    • 9 (2" x 6" x 6.3')
    • 6 (2" x 10' x 6.3') or 6 (2" x 4' x 6.3')

Water PressureEdit

Water gains 1 psi of pressure for every 2.31 feet of vertical rise. At the MLK site, with barrels raised to below the height of gutters on the roof of the shed we can achieve:

5ft. * 1 psi/2.31 feet = 2 psi

  • 2 psi is sufficient for irrigation using blue lined drip tape.

ResourcesEdit

Ad blocker interference detected!


Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers

Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.