Wastewater Reuse Oregon State University

GEO 300November 3, 2004

Russell HardingDepartment of Environmental QualityWater Quality Division(503) 229-5284harding.russell@deq.state.or.us

What is Treated Wastewater?

Wastewater from a municipal sewage treatment plant that has been treated (e.g. biologically or physically) to a level that allows its use for beneficial purposes (e.g. irrigation, manufacturing, construction purposes)

What is in Treated Wastewater?

waternutrients (low to moderate) pathogensorganics (biodegradable &

refractory)dissolved inorganics (Na, Ca, Mg,

B)metalsresidual chlorine

Reclaimed Water Sources

35,000 million gal/day wastewater (Solley et al. 1993)

– 925 million gal/day are reclaimed (or 3 percent)

» 650 million gal/day are irrigated

Industrial sources generate the highest volume of reclaimed water

Food processors generate most reclaimed water from industrial sources

Trend likely of increasing municipal sources, based on TMDL and temperature issues

Reclaimed Water Applied/Year in Oregon

1996 Figures

• Municipal 2727 million gal.

• Industrial 4836 million gal.

• Total 7563 million gal.

O r e g o n R e c l a i m e d W a t e r

O t h e r I n d u s t r i e s

5 %

M u n i c i p a l3 6 %

F o o d P r o c e s s o r s

5 9 %

Why Land Apply Reclaimed Water?

WQ limited streams may be adversely impacted by treated wastewater dischargesNeed the water for agriculture, pastures, plantation forestry, turf farms, golf courses, municipal projects: – Irrigation water may be seasonally limited– No other water available for a planned use

Can improve crop yield and soil productivity

Reclaimed Water Regulations

OAR Chapter 340 Division 55 (1991)

Beneficial use policy

WQ Permit - NPDES or WPCF

Reuse management plan

Oregon Water Reuse Policy

It is the policy of the Environmental Quality Commission to encourage the use of reclaimed waters for beneficial purposes using methods that assure that the health of Oregonians and the environment of the state are protected.

(OAR 340-055-0007)

Why Reuse?Of all the water on earth:

three percent is fresh water;

two percent is locked up as ice;

one percent of the world's water available for drinking. But that one percent is in trouble from:

impacts from demand versus supply (e.g. dessert communities)

pollution (e.g. historical discharges

lack of conservation (e.g. green, green lawns, pools, leaky pipes)

Land Application

• WPCF/NPDES permit required.• Except for water authorized by permit,

reuse plan required.• Health Services to approve plan.• DEQ may consider blending.• Water used on property not belonging to

treatment plant requires legally enforceable contract.

• No human consumption without EQC approval

Groundwater Protection

No water reuse authorized unless all requirementsof groundwater protection established in Division 40 are met.

Land application at rates that will not allow contaminants to leach to groundwater.

Water Reuse Plan

Reclaimed water use plan will demonstrate how a treatment plant operator will comply with these rules.

Reuse Management Plan Contents

• Facility Description (sources, flows)

• Treatment Process (disinfection)

• Effluent Characteristics (in detail)

• Storage (wintertime) and delivery system

• Contingencies (spills, upsets, start-up)

• Reporting (records)

• Intended Use Program (selecting sites)

Reuse Management Plan Contents

SITE• soils • topography • climate and micro-

climate• site limiting factors• surface and

groundwater• abutters

SITE RESTRICTIONSReclaimed water Levels 1-3

require:• Site access restrictions and

time delays prior to crop harvest

• Posted signs• Buffers around perimeter• Control of aerosol drift

Reuse Management Plan Contents

APPLICATION RATE• Key concept for agricultural

irrigation• Water balance• Nutrient needs• Salinity

IRRIGATION SYSTEM• Irrigation system Plans &

Specs (including pumping capacity & head ratings)

• Cropping system

Other Requirements

No bypassing of untreated water.Alarm devices and backup generators.Sufficient excess capacity to prevent discharge.Annual report required.Consumers required to read and understand rules.No water right conferred.

Treatment Requirements

Level I

Level II

Level III

Level IV

Biological Treatment

X X X X

Disinfection X X X

Clarification X

Coagulation X

Filtration X

Total Coliform (organisms/100 ml)

Level 1 Level II Level III Level IV

2 Consecutive Samples

N/L 240 N/L N/L

7-Day Median N/L 23 2.2 2.2

Maximum N/L N/L 23 23

Sampling Frequency

N/R 1/week 3/week 1/day

Turbidity (NTU)

Level I Level II Level III Level IV

24-Hour Mean

N/L N/L N/L 2

5% of Time in 24-hours

N/L N/L N/L 5

Sampling Frequency

Hourly

Public Access And Buffers

Level I Level II Level III Level IV

Public Access

Prevented

Controlled

Controlled No Contact during irrigation

Buffers

Surface: 10 ftSpray: Site Specific

Surface: 10 ftSpray: 70 ft

10 feet None

Allowable Uses

Level I Level II Level III Level IV

Agricultural Few Most Most All

Urban Irrigation

No Some Some Yes

Commercial/Industrial

No Yes Yes Yes

Construction No Yes Yes Yes

Impoundment

No Some Most Yes

Wastewater Reuse

Considerations

•Costs

•Land use issues

•In-Stream flow