PNS/BAFS/PAES 232:2017

PNS/BAFS/PAES 232:2017

Wastewater Re-use for Irrigation

Bicarbonates

Less than 500 mg/L

Biochemical Oxygen Demand (BOD₅)

Less than 150 mg/L

Electrical conductivity – restricted/access landscape

Less than 2,000 μS/cm

Electrical conductivity – food crops eaten raw / commercially processed

Less than 1,000 μS/cm

Electrical conductivity – non-food crops

Less than 2,000 μS/cm

Free residual chlorine

Less than 1 mg/L

pH

6.5–8.0

Sodium Adsorption Ratio (SAR)

Less than 18

Sodium (Na)

Less than 3 meq/L

Total nitrogen (TN)

Less than 30 mg/L

Total phosphorus (TP)

Less than 30 mg/L

Total suspended solids (TSS)

Less than 140 mg/L

Fecal coliform

Less than 200 MPN/100 mL

Aluminum

5

Arsenic

0.1

Silver

0.1

Beryllium

0.1

Boron

0.75

Cadmium

0.01

Chromium

0.1

Cobalt

0.05

Copper

0.2

Fluoride

1

Iron

1

Lead

0.2

Lithium

2.5

Manganese

0.2

Mercury

0.002

Molybdenum

0.01

Nickel

0.2

Selenium

0.02

Vanadium

0.1

Zinc

2

Aluminum

High toxicity in acid soils; not a concern if soil pH is greater than 6.5.

Cadmium

Higher toxicity in acid soils.

Lithium

Citrus limit: 0.075 mg/L.

Zinc

1 mg/L recommended for sandy soil with pH below 6.

Highly permeable soils

Avoid sandy and gravelly soils.

Extremely permeable soils

Avoid heavy clay, as stated in the standard.

Highly acidic soil

Avoid pH below 4.

Highly alkaline soil

Avoid pH above 8.5.

Preferred soil pH

5.5

Soil depth

Greater than 1.0 m

Direct contact

Must be avoided.

Sprinkler irrigation

Avoid fine mist to minimize aerosol dispersion by wind drift.

Water pipelines

Potable water and wastewater lines must not cross-connect.

Storage facilities

Must prevent seepage and have adequate freeboard.

Algal bloom

Immediately stop wastewater irrigation when algal bloom occurs.

Setback distance of Landscape – restricted area

30 m

Setback distance of Food crops commercially processed

30 m

Setback distance of Non-food crops

30 m

Setback from potable water supply wells for Landscape – restricted area (Sprinkler and drip)

90 m

Setback from potable water supply wells for Landscape – access area (Sprinkler and drip)

25 m

Setback from potable water supply wells for Food eaten raw and not commercially processed (Surface and drip)

25 m

Setback from potable water supply wells for Food crops commercially processed (Surface and sprinkler)

90 m

Setback from potable water supply wells for Non-food crops (Surface and sprinkler)

90 m

Soil intake rate for Clay

0.01–0.8 (Very slow–slow)

Soil intake rate for Silty clay

0.8–2.0 (Moderately slow)

Soil intake rate for Clay loam

2.0–6.0 (Moderately)

Soil intake rate for Loam

6.0–12.0 (Moderately rapid)

Soil intake rate for Sandy loam

12.5–25.0 (Rapid)

Soil intake rate for Sand

Greater than 25.0 (Very rapid)

Hydraulic conductivity (cm/h) for Clay

Less than 0.125–0.5

Hydraulic conductivity (cm/h) for Silty clay

0.5–2.0

Hydraulic conductivity (cm/h) for Clay loam

2.0–6.25

Hydraulic conductivity (cm/h) for Loam

6.25–12.5

Hydraulic conductivity (cm/h) for Sandy loam

12.5–25.0

Hydraulic conductivity (cm/h) for Sand

Greater than 25.0