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Rainwater harvesting & irrigation

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How to design your rainwater harvesting system to work with an irrigation system,

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Rainwater harvesting & irrigation

  1. 1. Rainwater Harvesting & Irrigation Using Rainwater as a supplemental source of water for your landscape irrigation systemBy Sean Mullarkey CID, CLIA, CIC, CGIA513.379-5780
  2. 2. What comes down goes around?• Can we catch all the rain?• Do we need all the rain?• How can we use all the rain?
  3. 3. Cincinnati Weather Jan Feb M ar A pr M ay Jun Jul A ug Sep Oct Nov DecA vg. Hi gh 38° 42° 54° 65° 75° 84° 86° 85° 78° 67° 54° 44°A vg. Low 21° 24° 34° 44° 52° 61° 66° 64° 57° 44° 35° 26°M ean 30° 34° 44° 54° 64° 72° 76° 75° 68° 56° 45° 35°A vg. P r eci p. 50 2. 2. 50 4. 30 3. 70 4. 40 3. 40 4. 10 3. 70 3. 10 2. 80 3. 30 3. 10A vg. E T 0. 62 1. 12 2. 17 3. 60 5. 27 6. 30 6. 51 5. 90 4. 20 2. 79 1. 20 0. 62 What is Effective Rainfall ver. Actual Rainfall?
  4. 4. How do we catch it?
  5. 5. Don’t Let It Get Away!• Sources of Rain Water? “I wasn’t thinking the sky!” – Roofs • Least amount of pollutants • Elevation of gutter allows directing to tank without pump • Easy to pre-filter and provide first flush • Low cost of conversion – Pavement • Dirt and pollutants are more abundant • May need pumps to move water to storage area • Can be expensive to convert for collecting Rain, more cost effective if done during construction
  6. 6. Don’t Let It Get Away!• Sources of Rain Water? – Landscape Areas • Detain or Retain? • Contour planting • Rain Gardens • Soil improvements
  7. 7. Site Comparison Area Home 1” Rain Bank 1” Rain Land SF 22700 45500 Pavement SF 900 24200 Roof SF 1200 748 gal 5800 3613 gal Landscape/turf SF 20600 91% 15500 34%Rainwater Formula ( SF x .623 = Gal. Collected for 1 inch rainfall).623 is a constant that coverts Square Feet to Gallons
  8. 8. How to figure the Sq. Ft. of a roof
  9. 9. Home PWR / AW Plant Water Requirement / Available Water1,200,000 Home Property1,000,000 800,000 Water needed for plants 600,000 Rain Total Available 400,000 200,000 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
  10. 10. Bank PWR / AW Plant Water Requirement / Available Water800,000 Bank Property700,000600,000500,000 Water needed for plants400,000 Rain Total Available300,000200,000100,000 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
  11. 11. What are we going to water• What are we going to use the water for• When will we need it.• Where will it be located
  12. 12. How much water do our plants need?• Practical methods , the kind you use every day• Management methods, depends on how much management budgets for watering• Scientific Methods, good for developing a base line to use along with your practical methods
  13. 13. Plant Water Requirement (PWR)• PWR = Landscape Coefficient X Reference ET KL = KP x Kd x Kmc • KL = landscape coefficient • KP = plant factor • Kd = vegetation density factor • Kmc = microclimate factor
  14. 14. Plant FactorPlant type Maximum Acceptable Low maintenance appearance appearanceTrees 0.90-0.95 0.70-0.75 0.45-0.50Shrubs 0.60-0.65 0.45-0.50 0.30-0.35Desert plants 0.40-0.45 0.30-0.35 0.20-0.25Ground covers 0.70-0.80 0.50-0.60 0.30-0.40Mixed planting 0.90-1.00 0.75-0.80 0.50-0.55
  15. 15. Kd = vegetation density factorKd refers to the collective leaf area of the plants covering or shadingan area of groundMore foliage equals more transpiration hence more water is needed.
  16. 16. Kmc = microclimate factorPlants growing is shade need less waterPlants growing next to a brick wall on thesouth side of a building need more water
  17. 17. Calculating PWR6.5”/month * .7 = 4.61200 SF of plantings(1200 x 4.6) = 460CF of water 12 460 x 7.48 = 3440 Gal for month7.48 gal per CU FT of water
  18. 18. Large Underground Tank
  19. 19. Rain Water Storage
  20. 20. Rain Water Storage
  21. 21. Rain Water Storage
  22. 22. Storage Tank Cost MATERIAL COST, Small System COST, Large system galvanized steel $225 for 200 gallons $950 for 2000 gallons polyethylene $160 for 165 gallons $1100 for 1800 gallons fiberglass $660 for 350 gallons $10,000 for 10,000 gallons ferro-cement Price variable upon location Price variable upon locationfiberglass/steel composite $300 for 300 gallons $10,000 for 5000 gallons aluminum Cost prohibitive for water use Cost prohibitive for water use http://www.lid-stormwater.net/raincist_cost.htm
  23. 23. Using the Rain Water• Most Rainwater Harvesting System are best utilized watering landscape plantings not turf because of the limited size of storage units• If you have a large storage area such as a lake all planted areas can be watered with the stored rainwater• Most systems will need some sort of pump to distribute the water through a pipe net work
  24. 24. Amount of water needed per 100 Sq. Ft. per month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecGal/ 27 49 95 157 230 275 284 257 183 122 52 27100SF
  25. 25. Types of irrigation for landscape Beds • Hand Watering • Pros: – Can apply varying amounts of water to specific plant – Can conserve water resources – Allows for visual inspection of plants – Equipment cost are low
  26. 26. Types of irrigation for landscape Beds• Hand Watering• Cons: – Labor cost are very high – Need skilled labor – Time consuming
  27. 27. Types of irrigation for landscape Beds• Automatic overhead irrigation• Pros: – Well designed systems eliminate waist – Very low labor needs – Large water window (application time) – Frees up labor for other task
  28. 28. Types of irrigation for landscape Beds• Automatic overhead irrigation• Cons: – High initial expense – Mostly a shotgun approach – Blocked easily by plant material – Inflexible to alterations – Wets foliage
  29. 29. Types of irrigation for landscape Beds Drip and low volume irrigation Pros:  Highest potential efficient use of water  Low labor needs  Economical to install  Largest water window  Places water at or near the roots  Keeps foliage dry  Low precipitation rates
  30. 30. Types of irrigation for landscape Beds• Drip and low volume irrigation• Cons: – Can be unsightly – Easily damaged when working in the beds – Hard to visually inspect its operation – Needs clean water
  31. 31. Best types of irrigation for landscape Beds Drip and low volume irrigationMost cost effective in the long term, utilizes the ever more precious resource of water better than any method, will get you LEED points , very flexible to change, can be unsightly if not installed properly.
  32. 32. Best types of irrigation for landscape Beds• Controlling the rate of application – Drip and low volume irrigation have very low precipitation rates. Hand watering can be controlled to eliminate run off as well. • No run off • Will not remove air from soil unless it is allowed to run for to long of an irrigation cycle – Over head irrigation generally has a very high precipitation rate , so do hose end sprinklers
  33. 33. Best types of irrigation for landscape Beds• Low volume irrigation provides the most advantages over the alternative methods – Efficient use of water – LEED qualified (GREEN) – Waters better than most rain storms as considered against uniformity and precipitation rate – Drip goes hand in hand with rain water harvesting
  34. 34. Best types of irrigation for landscape Beds• Rain water harvesting – If you are using any type of cisterns to capture rain water, drip is an Ideal way to use that water • Need to filter the water before use • If water is from pavements check for soluble salts and other contaminants
  35. 35. Down Load This Presentation• ftp.appliedwatertechnologies.com• Name: rainwater@appliedwatertechnologies.com• Password: tri_stateGIE

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