NYC Graywater irrigation feasibility study
NYC Graywater irrigation feasibility study
(OP)
I am conducting a feasibility study for the beneficial reuse of extracted urban groundwater for the irrigation of turf grass with some deciduous trees. The approximate coverage area to be irrigated is between 100,000 and 200,000 sf. Though the extracted groundwater is from inland Brooklyn, NY, it's chemistry has been altered due to saltwater infiltration that has occurred as a result of over 100 years of deepwell pumping in the area. The extracted groundwater currently flows through a main line between 3,000 and 5,200 gpm and discharges into a city stormwater sewer. The following chemistry is from water samples taken from the discharge line we would be tapping for graywater irrigation purposes:
Sodium (ug/L) – 184,000
Calcium (ug/L) – 159,000
Magnesium (ug/L) – 68,200
Hardness as Calcium Carbonate (mg/L) – 676
Specific conductance (umhos/cm) – 2,200
Chloride (mg/L) – 614
TDS (mg/L) – 1,200
TSS (mg/L) – 1.3
Salinity (mg/L) – 467.9
The approximate calculated Sodium Absorption Ratio is 3.03.
Would treatment of this groundwater be necessary or recommended for grass irrigation? If so what options would be available?
In addition to water quality goals, what would be rough estimate for the anticipated system flow to irrigate such an area?
Thank you very much!
Regards,
Robert Fields
Sodium (ug/L) – 184,000
Calcium (ug/L) – 159,000
Magnesium (ug/L) – 68,200
Hardness as Calcium Carbonate (mg/L) – 676
Specific conductance (umhos/cm) – 2,200
Chloride (mg/L) – 614
TDS (mg/L) – 1,200
TSS (mg/L) – 1.3
Salinity (mg/L) – 467.9
The approximate calculated Sodium Absorption Ratio is 3.03.
Would treatment of this groundwater be necessary or recommended for grass irrigation? If so what options would be available?
In addition to water quality goals, what would be rough estimate for the anticipated system flow to irrigate such an area?
Thank you very much!
Regards,
Robert Fields





RE: NYC Graywater irrigation feasibility study
http://www.ext.colostate.edu/pubs/crops/00506.html
The only option for treatment is desalination with RO treatment.
You probably would need a peak water supply of around 5,000 gallons per acre per day.
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RE: NYC Graywater irrigation feasibility study
RE: NYC Graywater irrigation feasibility study
RE: NYC Graywater irrigation feasibility study
RE: NYC Graywater irrigation feasibility study
This question does not have a simple answer because irrigation requirements vary with grass species, with soil type, and with environmental conditions. These factors often interact in complex ways that make decision making difficult. On average, turf will usually require from 1 to 1.5 inches of water per week for normal maintenance conditions. This can be provided by rainfall or irrigation or a combination of the two.
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Note that variations of turf grass may have vastly different watering needs. Whole books have been written on the subject.
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RE: NYC Graywater irrigation feasibility study
RE: NYC Graywater irrigation feasibility study
RE: NYC Graywater irrigation feasibility study
bimr, the documents you have provided have proven very useful.
I would like to explore the option of ion exchange. EIther cation, anion or some combination of the two to reduce the Chloride and hardness levels. Do you have any experience with such systems? From what I have seen they would cost less than RO (in the order of $100k or less for our size application). What would the ions be replaced with after treatment and what unintended consequences, if any, could one expect from these? How about specifying a system that would tailor itself to the specific ions I want to remove. Would this be possible?
RE: NYC Graywater irrigation feasibility study
RE: NYC Graywater irrigation feasibility study
RE: NYC Graywater irrigation feasibility study
Ion exchange was the only demineralization process available at one time. Ion exchange is now generally only used as a polishing step after RO because RO is more cost effective.
Call a supplier of ion exchange systems such as Siemens Water or Graver for information and costs, not a consultant.