DECENTRALIZED TREATMENT: Moving toward Sustainability. Jim Kreissl USEPA ORD, retired

Size: px

Start display at page:

Download "DECENTRALIZED TREATMENT: Moving toward Sustainability. Jim Kreissl USEPA ORD, retired"

Derick Charles
6 years ago
Views:

1 DECENTRALIZED TREATMENT: Moving toward Sustainability Jim Kreissl USEPA ORD, retired

2 WHAT IS SUSTAINABILITY? Most accept the Brundtland Commission s definition: development that meets the needs of the present without comprimising the ability of future generations to meet their own needs. Another definition is meeting the needs of humans and nature for the long term

3 DEPICTION OF SUSTAINABLE DEVELOPMENT DECISION-MAKING Social Equity Economy Environment

4 TYPICAL ONCE-THROUGH URBAN WATER MANAGEMENT SYSTEM Precipitation Water supply Urban area Water returned directly (storm sewers) and indirectly (sanitary sewers) to surface waters often several drainage basins downriver from water supply source

5 HOW DOES SUSTAINABILITY APPLY TO WATER QUANTITY ISSUES? The urban (once-through) approach with conventional centralized technology has proven to worsen soil drying by lowering ground water tables due to infiltration into leaky, deeply-buried (typically 25 ft or more) sewers, while reducing sewer capacity to carry sewage (eg, Boston and Long Island)

6 HOW BAD ARE THESE LOSSES? In the Boston area, 60% of the sewer capacity is used for carrying clear water from infiltration USEPA s own standards for acceptance of newly constructed sewers could result in clear water using 40% of pipe capacity when the sewer is below the water table

7 WHAT ARE THE IMPACTS? Residential, agricultural, industrial, and community wells needs to be extended deeper to retain capacity, increasing costs and energy required to operate. Cities are asking huge rate-hikes to upgrade existing leaky sewers that mostly carry infiltrated water and to expand treatment facilities that are treating mostly clear water.

8 ANY OTHER WATER QUANTITY ISSUES? Lots!! Starting with stream flow issues Because storm-sewer based development quickly misdirects surface runoff that would normally infiltrate the soil directly to ground water, resulting in local stream overflows during these wet periods and abnormally low flows during dry ones The overall effects include depleted aquifers and reduced evapotranspiration which can cause heating and drying of the land

9 STORMWATER FATE vs DEVELOPMENT

10 HOW DOES THIS RELATE TO WATER QUALITY? The biggest source of surface water contamination in the US is storm runoff from agricultural fields and urban areas Excessive, first-flush, runoff leads to flashy streams that erode stream banks and become polluted with sediment, pathogens, and nutrients Ground water quality degrades faster without dilution from percolation of precipitation that forests, prairies, and other pervious areas provide

11 TYPICAL RURAL WATER MANAGEMENT Water from private/public wells Precipitation Rural community or single dwelling Indoor usage returned to local ground water after soil treatment Most precipitation and outdoor usage returned to local ground water

12 TRADITIONAL SEPTIC SYSTEMS

13 HOW ABOUT NUTRIENTS FROM ONSITE WASTEWATER SYSTEMS? Modeling data imply onsites can make a major nutrient contribution to nearby surface waters based on their presence in the area TMDLs must be performed on local watersheds to show the relative amount of total pollutant contributions that are from septic systems. Onsite systems located in riparian zones (especially in karst, fine soils, and steep slopes) can contribute significant levels of nitrogen to receiving waters, so that more complex onsite designs are needed in those areas.

15 PHOSPHORUS Phosphorus is generally removed from the effluent as it passes through the soil after infiltration Since P-removal is dependent on soil surface area and reactivity, it generally reduces with time Uniform dosing/resting high in the soil profile maximizes the capability to remove P from the effluent. If reuse for irrigation is planned, P-removal would be counterproductive

16 ONSITE SYSTEM MAJOR CONTAMINANTS The primary contaminants from poorly-sited or poorly-performing onsite systems are pathogens, which is the #1 stream contaminant that comes from human wastes and runoff In most cases, wastewater nitrogen travels to ground water and then to nearby surface waters fed by those aquifers (controlled by soil characteristics, hydrogeology, and technology) Phosphorus is generally removed by local soils EDCs and other unregulated chemicals are likely better removed in the soil than by treatment plants

17 WHAT IS THE DECENTRALIZED APPROACH? It is a holistic, cost-efficient method of solving water quality and quantity problems. It requires an effective and sustainable management program. It targets the biggest problem areas and minimizes infrastructure investment. It employs simple technologies and maximizes soil dispersal and reuse opportunities.

18 TYPICAL CHARACTERISTICS CENTRALIZED Conventional gravity sewers Single treatment facility Discharge to surface water DECENTRALIZED Onsite or alternative collection system Multiple treatment facilities Discharge to ground water or reuse

19 A VISUAL DESCRIPTION Centralized wastewater treatment Decentralized approach

20 DECENTRALIZED/DISTRIBUTED PLANNING/DESIGN STRATEGY Use the most passive technologies that can meet performance requirements Reuse and aquifer recharge preferred over conventional receiving water discharge Minimize inter-basin transfer of water Management program is appropriate to technologies chosen Maximize use of viable existing systems

Minimal initial investment, satisfy the need.

21 WHY IS THIS A GOOD THING? Existing Communities Can solve wastewater and other water-related problems. Minimal initial investment, satisfy the need. Developers Allows more lots and greater open space. Open and common areas can serve as soil dispersal and/or reuse facility locations and social amenities. Increased developer profits and resident aesthetics.

22 SO HOW CAN SUSTAINABILITY APPLY TO ONSITE AND DECENTRALIZED SYSTEMS? Local area and watershed management decisions need to be based on sustainable life-cycle costs and energy requirements of system components, as well as on community protection, vision, and aesthetics Distributed wastewater management must be made an integral part of the land-use planning processes, local ordinance upgrades, and state regulations in order to approach sustainability Onsite/decentralized systems can minimize energy demands required to maintain performance, promote reuse of wastewater and stormwater, and can be aesthetically pleasing and compatible with any community vision

23 SO HOW CAN ONSITE AND DECENTRALIZED SYSTEMS IMPROVE SUSTAINABILITY? Compared to conventional sewer systems these technologies minimize the energy required to fabricate, transport, and construct through use of lightweight/recycled components, minimal transport costs/energy, and low-energy, lesstime-consuming construction techniques Decentralized wastewater and stormwater management approaches minimize impacts on local hydrology and enhance local community aesthetics, health, and economy while assuring needed quantity and quality of water resources to support long-term community goals

24 CONVENTIONAL SEWERS

25 THE CONVENTIONAL SEWER SOLUTION Collection Pipe System Deep (8 to 25 feet) pipes, with frequent (every feet) manholes, and lift stations to maintain gravity flow at minimum velocity (75 to 85% of total facilities cost) Treatment System A single large treatment facility, usually some form of activated sludge, with additional processes as necessary to meet discharge standards Discharge - Usually, direct surface water discharge; in some cases soil discharge is required, but in all cases extracted waters from several upstream basins are transferred to one downstream location

26 COMPARISONS CENTRALIZED Old and taught High capital cost Transfers water away from source Long, disruptive construction Skilled operator need DECENTRALIZED New and not taught Lower capital costs Keeps water close Short, less-disruptive construction Basic operations skills required

27 WHICH DECENTRALIZEDTECHNOLOGIES ARE MOST OFTEN USED? Septic Systems Most passive and effective system where local conditions permit. Better Pretreatment Fixed-film and filter alternatives are more robust, perform more reliably, and need less O/M than activated sludge types. For special locations, membranes replace settling and attain reuse quality Better Soil Dispersal The larger the system capacity, the greater the need for pressurized or drip distribution and resting to maximize soil contact time and treatment potential. Low-Cost Collection Minimizes capital and O/M costs, infiltration/inflow, and construction duration and community disruption.

inflow (I/I) owing to shallow burial, fewer and tighter joints, and lack

28 LOW-COST COLLECTION SYSTEMS Alternative collection systems (ACS) almost always have significantly lower capital costs ACS reduces infiltration and inflow (I/I) owing to shallow burial, fewer and tighter joints, and lack of manholes Require less community disruption and construction period duration

29 LOW-COST COLLECTION SYSTEMS Effluent Sewers (STEG and STEP) Effluent Sewer (STEG) Composed of: interceptor tanks (& pumps for STEP) Shallow, small dia. mains w. fewer pipe joi and cleanouts

30 LOW-COST COLLECTION SYSTEMS Grinder Pump System Grinder Pump System Grinder Pump To Treatment Composed of: small-diameter pressurized collection system Grinder/pump with controls Like vacuum, leaves no residuals on lot

31 LOW-COST COLLECTION SYSTEMS Vacuum Sewers Vacuum System Vacuum System is composed of: holding tanks with vacuum valves Small diameter collection pipes Central vacuum collection station/no electric connection on lot

33 SINGLE-PASS MEDIA FILTERS Inspection Riser Service Manhole Inlet Watertight Tank Outlet Pipe to Dispersal System

34 VEGETATED SUBMERGED BED AKA: SUBSURFACE FLOW WETLAND

35 FLEXIBILITY TO MEET PERFORMANCE DEMANDS

36 SOIL DISTRIBUTION Better distribution and shallow placement allows the entire soil infiltration area to be used: provides better oxygen diffusion for aerobic treatment by microbes increases the contact time between the wastewater and soil, and enhances nitrogen removal

37 PRESSURE DISTRIBUTION

38 Drip Dispersal Filtration Unit House Treatment Tank Well Pump Tank Drip Tubing (2 Feet On Center) Shed Property Line

39 MANAGEMENT PROGRAM Distributed/decentralized solutions require a responsible management program Most surveys show that homeowners are willing to pay about $30 to $40 per month for efficient wastewater services (most do) The challenge is to develop an effective and sustainable WATER management program at the least cost to the community

40 MORE BASIC MANAGEMENT PRINCIPLES The management entity does not need to perform every functional element of their management program. They can contract with trained and certified service providers to perform field work, or require citizens to enter into contracts with those service providers, overseen by the management program Keep the community involved on review boards and advisory councils to reinforce their program ownership Make compliance rules as friendly as possible, with transparent enforcement and monetary incentives Involve the regulators in the process to avoid misinterpretations and build trust.

41 WHAT ARE SOME TOWNS DOING? Converting sludge digesters to co-digestion energy generators by accepting local industrial/commercial organic wastes and producing reusable methane gas Reusing stormwater and treated wastewater for irrigation of golf courses and municipal parks and toilet flushing Limiting impervious surfaces and storm sewers and maximizing reuse opportunities in new developments with cisterns and rain gardens Using just in time infrastructure investments Preserving the most ecologically valuable lands that sequester carbon and promote ecological processes Providing economic incentives to reward homeowners and others for incorporating green concepts

42 WHERE ARE DECENTRALIZED APPROACHES BEING USED? There are scores of such distributed management and decentralized technology solutions employing decentralized technologies across the US The following examples are categorized by the types of problems being addressed by them, but many more exist than these.

43 PROTECTION /RESTORATION OF SURFACE WATERS Lake Panarama, Iowa Otter Tail Lake, Minnesota Keuka Lake, New York Georgetown Divide PUD, California Stinson Beach, California Charlotte County, Florida Nags Head, North Carolina

44 GROUNDWATER QUALITY PROTECTION Block Island, Rhode Island Westbrook, Connecticut Tisbury, Massachusetts La Pine, Oregon Willard, New Mexico

45 MULTIPLE PROBLEMS Paradise, California surface/ground water quality Sea Ranch, California surface water quality and hydraulic failures of septics Pena Blanca, New Mexico ground water quality and hydraulic failures of septics Cuyler, New York surface water quality and hydraulic failures of septics

46 THANKS FOR YOUR ATTENTION Any Questions?

Decentralized Wastewater Systems

Decentralized Wastewater Systems Decentralized and Traditional Wastewater Treatment Systems Mark Gross, Ph.D., P.E. Training Manager Orenco Systems, Inc. Decentralized Overview 3/3/2010 #1 Some Aspects