Wastewater Systems Wastewater Systems Wastewater Systems Dave - - PowerPoint PPT Presentation

Wastewater Systems Wastewater Systems Wastewater Systems

Dave Lenning Washington Dept. of Health Dave Lenning Dave Lenning Washington Dept. of Health Washington Dept. of Health

2

Our Focus: Our Focus:

Wastewater issues & options for small communities

Decentralized and centralized Relationship to land use planning

Wastewater in Washington State Briefly, general issues on technology Wastewater issues & options for small communities

Decentralized and centralized Relationship to land use planning

Wastewater in Washington State Briefly, general issues on technology

3

Wastewater System Continuum Wastewater System Continuum

Centralized Centralized Centralized

Treatment Plant Treatment Treatment Plant Plant

Individual Individual Individual

Decentralized Decentralized Decentralized

Scale of Service Scale of Scale of Service Service

Cluster Cluster Cluster Central Central Central Regional Regional Regional Individual Building

• r

Property Individual Individual Building Building

• r
• r

Property Property Part of a community

• r

subdivision Part of a Part of a community community

• r
• r

subdivision subdivision Entire town, city, village,

• r

community Entire town, Entire town, city, village, city, village,

• r
• r

community community Two or more towns, cities, villages, or communities Two or more Two or more towns, cities, towns, cities, villages, or villages, or communities communities

Level of Centralization Level of Centralization Level of Centralization

4

Example 1: Typical arrangement for 10 lots – Individual Systems Example 1: Typical arrangement for 10 lots – Individual Systems

1 2 3 4 5 6 7 8 9 10

5

Example 2: Possible arrangement for clustering 10 lots Example 2: Possible arrangement for clustering 10 lots

1 2 3 4 5 6 7 8 9 10 Greenbelt Community Area DF DF DF DF

6

Example 3: Another possible arrangement for clustering 10 lots Example 3: Another possible arrangement for clustering 10 lots

Greenbelt or Community Area DF DF 1 2 3 4 5 6 7 8 9 10

7

Wastewater Systems Wastewater Systems

Both centralized and decentralized:

Collect wastewater from each home or

business

Treat wastewater to reduce contaminant

levels

Discharge/Disperse treated wastewater in

way that won’t adversely affect public health or the environment

Both centralized and decentralized:

Collect wastewater from each home or

business

Treat wastewater to reduce contaminant

levels

Discharge/Disperse treated wastewater in

way that won’t adversely affect public health or the environment

8

Decentralized vs. Centralized Questions: Decentralized vs. Centralized Questions:

Which does the public like best? Which is best for the environmental protection? Which is most cost-effective? How does an existing small community decide? Which does the public like best? Which is best for the environmental protection? Which is most cost-effective? How does an existing small community decide?

9

It’s a fact: It’s a fact:

We have experts in centralized systems and experts in decentralized systems Very few are expert in both Some potential for bias when planning the wastewater infrastructure of an area We have experts in centralized systems and experts in decentralized systems Very few are expert in both Some potential for bias when planning the wastewater infrastructure of an area

10

Reality to be recognized: Reality to be recognized:

Most wastewater infrastructure planning - done by experts in centralized systems Makes getting decentralized systems to be considered more difficult Many engineers, public/private utilities, politicians are convinced - the only good, long-term system is a centralized system Most wastewater infrastructure planning - done by experts in centralized systems Makes getting decentralized systems to be considered more difficult Many engineers, public/private utilities, politicians are convinced - the only good, long-term system is a centralized system

11

Decentralized Systems Decentralized Systems

Use same science as centralized systems Can produce high effluent quality But:

Not the best reputation Poor history of proper use and care Quality and quantity are variable

Is it worth the effort to try and overcome the problems? Use same science as centralized systems Can produce high effluent quality But:

Not the best reputation Poor history of proper use and care Quality and quantity are variable

Is it worth the effort to try and overcome the problems?

12

In 1997 USEPA said “YES” In 1997 USEPA said “YES”

“Adequately managed decentralized wastewater treatment systems can be a cost-effective and long- term option for meeting public health and water quality goals, particularly for small, suburban and rural areas.”

13

Decentralized Wastewater Systems Decentralized Wastewater Systems

1997 Response to Congress lists potential benefits:

Protection of public health & environment Provides flexibility – can target technologies

Varying site conditions Varying sensitivities of receiving environments

Smaller problem areas Longer service lives for managed systems More cost effective, except in densely

populated areas

1997 Response to Congress lists potential benefits:

Protection of public health & environment Provides flexibility – can target technologies

Varying site conditions Varying sensitivities of receiving environments

Smaller problem areas Longer service lives for managed systems More cost effective, except in densely

populated areas

14

Wastewater Systems Wastewater Systems

Need to better understand pros/cons of both centralized and decentralized systems Need to better understand pros/cons of both centralized and decentralized systems

15

Wastewater Systems Wastewater Systems

Centralized Centralized Decentralized Decentralized Characteristic or Characteristic or Attribute Attribute

Relatively large Relatively large amounts amounts Relatively small Relatively small amounts amounts

Sewage Volume Sewage Volume

Gravity sewer + Gravity sewer + alternatives alternatives Gravity effluent + Gravity effluent + alternatives alternatives

Type of Collection Type of Collection

Typically activated Typically activated sludge + alternatives sludge + alternatives Septic tank + Septic tank + alternatives alternatives

Treatment Type Treatment Type

Typically, into surface Typically, into surface water or onto land water or onto land surface surface Typically, into the soil Typically, into the soil

Dispersal or Dispersal or Discharge Discharge

16

Wastewater Systems Wastewater Systems

Centralized Centralized Decentralized Decentralized Characteristic or Characteristic or Attribute Attribute

Some variance from Some variance from state to state, but state to state, but more consistency more consistency Vary considerably Vary considerably from state to state & from state to state & county to county county to county

Applicable Rules Applicable Rules

Performance based Performance based Historically, very Historically, very prescriptive prescriptive

Requirements & Requirements & Standards Standards

Can flush & forget Can flush & forget Can’t flush & forget Can’t flush & forget

Convenience for Convenience for system users system users

Usually, a concern, Usually, a concern, especially with especially with conventional gravity conventional gravity Usually, little concern Usually, little concern

I & I I & I

17

Wastewater Systems Wastewater Systems

Centralized Centralized Decentralized Decentralized Characteristic or Characteristic or Attribute Attribute

Public (POTW) Public (POTW) Individual or private Individual or private

Ownership Ownership

Historically, more Historically, more readily available and readily available and easier to obtain easier to obtain Historically, more Historically, more limited and difficult to limited and difficult to find find – – this is changing this is changing

Availability of Availability of funding funding

Preferred option, Preferred option, most convenient most convenient Bad reputation, lack of Bad reputation, lack of maintenance has hurt maintenance has hurt

Public Public acceptance acceptance

Will be needed Will be needed If individual tanks If individual tanks – – no no easements; if cluster easements; if cluster – – some needed some needed

Need for Need for easements easements

18

Wastewater Systems Wastewater Systems

Centralized Centralized Decentralized Decentralized Characteristic or Characteristic or Attribute Attribute

Can be disruptive to Can be disruptive to large neighborhood large neighborhood Limited to single Limited to single home or cluster home or cluster

Consequences of Consequences of failure failure

Many options Many options – – costly costly to modify/inflexible to modify/inflexible

• nce installed
• nce installed

Considerable and Considerable and growing fast growing fast – – can be can be very flexible very flexible

Flexibility of Flexibility of technical options technical options

Tends to promote Tends to promote growth, more homes growth, more homes = greater return = greater return Doesn’t promote, but Doesn’t promote, but can accommodate, can accommodate, some fit on small lots some fit on small lots

Impacts on growth Impacts on growth

Critical Critical Critical Critical

Need for Need for management management

Sufficient samples to Sufficient samples to meet “averages” meet “averages” Historically, not 7 or Historically, not 7 or 30 day averages 30 day averages

Sampling Sampling frequency frequency

19

Decentralized Considerations: Decentralized Considerations:

Can achieve high pollutant removal rates

95%+ removal BOD/TSS 99%+ removal of FC Can add components for other parameters

Often much more affordable for small communities Homeowners/Communities concerned with failure rate Can achieve high pollutant removal rates

95%+ removal BOD/TSS 99%+ removal of FC Can add components for other parameters

Often much more affordable for small communities Homeowners/Communities concerned with failure rate

20

Decentralized Considerations: Decentralized Considerations:

Not as convenient as centralized – can’t “flush and forget” Just like centralized systems, requires:

Proper siting and design Proper installation On-going proper use and care – O&M

Many benefits and considerations in Rocky Mountain Institute publication Not as convenient as centralized – can’t “flush and forget” Just like centralized systems, requires:

Proper siting and design Proper installation On-going proper use and care – O&M

Many benefits and considerations in Rocky Mountain Institute publication

21

Centralized Considerations Centralized Considerations

Unaffordable for many small communities Shellfish harvesting prohibited near

• utfalls

Need dense development and population to pay for it – affects growth planning Can provide high levels of treatment Management typically is easier Unaffordable for many small communities Shellfish harvesting prohibited near

• utfalls

Need dense development and population to pay for it – affects growth planning Can provide high levels of treatment Management typically is easier

22

EPA Guidelines: Models EPA Guidelines: Models EPA Guidelines: Models

Management Through:

Model 1 - System Inventory & Maintenance Awareness Model 2 - Maintenance Contracts Model 3 - Operating Permits Model 4 - Utility Operation and Maintenance

• Model 5 - Utility Ownership and

Management

Management Through:

Model 1 Model 1 - System Inventory & Maintenance Awareness Model 2 Model 2 - Maintenance Contracts Model 3 Model 3 - Operating Permits Model 4 Model 4 - Utility Operation and Maintenance

• Model 5

Model 5 - Utility Ownership and Management

Lower Level Management Higher Level Management

23

Management of Wastewater is a Major Challenge in the Puget Sound Basin

Both meet or exceed secondary treatment standards Both are capable of higher treatment Both create water quality challenges

SUMMARY

< 2,000 acres (where only source) Small, localized areas (1-2 acres) Variable depending on location 10 long-term (2005 – 2006) ≈28,000 (excluding urban bays) Large areas (100s – 1,000s acres) >1.3 billion gallons/year3 57 Short-term (2005 – 2006)

Water Quality Impacts

– Shellfish Acres Permanently Closed – Shellfish Area Closed/Outfall or Failure – Pipe breaks, Sewer Overflows, Failures – Public Swimming Beach Closures 175 Million GPD 400 Million GPD

Total Volume

High

(but greater risk if failure)

Limited

(reclaimed water; upland spray)

Groundwater Recharge

10-40% Basic System2

(Much more with nitrogen removal)

10-40%1

(much more with tertiary treatment)

Nitrogen Reduction

Limited Daily

Operation and Maintenance

1.15 Million (29%) 2.85 Million (71%)

Population Served

(projected increase of 35% by 2025)

Sewers

(discharge to surface water)

Septic Systems

(discharge into soils)

Issue

2Onsite Wastewater Systems Manual, EPA/625/R-00/008, Table 3-17, February 2002

1LOTT: ≈5% of 400 million GPD 32002 Ecology CSO Focus Sheet

Data source: DOH Office of Shellfish and Water Protection 11/2006

24

Consider: Wastewater Systems Consider: Wastewater Systems

Stop using labels… Stop using labels…

All systems part of wastewater infrastructure All systems need adequate management Why are labels then needed?

25

Wastewater Infrastructure Planning Wastewater Infrastructure Planning

Using land use plan - consider all

• ptions

USEPA Response to Congress:

Combination of individual, cluster, and centralized may be best choice for many communities

Rocky Mountain Institute: “Optimal

architecture” for wastewater systems should be much more a mixture of centralized and decentralized than commonly encountered today

Using land use plan - consider all

• ptions

USEPA Response to Congress:

Combination of individual, cluster, and centralized may be best choice for many communities

Rocky Mountain Institute: “Optimal

architecture” for wastewater systems should be much more a mixture of centralized and decentralized than commonly encountered today

26

Consider: Wastewater Systems Consider: Wastewater Systems

Population Density Population Density LOW LOW HIGH HIGH Soils GOOD GOOD POOR Soils POOR Individual Individual Cluster Cluster Sewer/TP Sewer/TP Wastewater Systems Wastewater Systems

27

Wastewater Infrastructure Planning Wastewater Infrastructure Planning

All systems in jurisdiction – part of jurisdiction’s wastewater infrastructure All systems in jurisdiction – part of jurisdiction’s wastewater infrastructure

28

Wastewater Infrastructure Planning Wastewater Infrastructure Planning

▲Different Approaches ▲Different Approaches

29

Wastewater Infrastructure Planning Wastewater Infrastructure Planning

BUT community must first plan its future

• how it will grow/sustain itself

Then, wastewater infrastructure plan - dependent on land use/growth management plan BUT BUT community must first plan its future

• how it will grow/sustain itself

Then, wastewater infrastructure plan - dependent on land use/growth management plan

30

Pacific Northwest Differences Pacific Northwest Differences

31

On-site Sewage Regulatory Framework On Washington On-

• site Sewage Regulatory Framework

site Sewage Regulatory Framework Washington Washington

Systems >100,000 All: > 14,500 Mechanical: > 3,500

• Dept. of Ecology

All: 3,500– 100,000 3,500–14,500 (Non-mechanical)

• Dept. of Health

≥ 3,500 ≥ 3,500 Local Health Proposed Proposed (Gallons/Day) (Gallons/Day) Current Current (Gallons/Day) (Gallons/Day) Regulatory Regulatory Authority Authority

Approximate equivalencies: 3,500 gpd ≈ 10 houses or a small strip mall ≤14,500 gpd ≈ large restaurant or grocery store, 45 houses 100,000 gpd ≈ 300 houses

32

Washington Agencies Washington Agencies

Reclaimed Water Use – shared review responsibility

Health – greywater, industrial Ecology – Other projects with assistance

from Health

Reclaimed Water Use – shared review responsibility

Health – greywater, industrial Ecology – Other projects with assistance

from Health

33

Philosophy - Rules Philosophy - Rules

SBOH

Applies to both local and state health State rules are minimum rules for local

health

Washington – local government is where the

action is, where final decisions made

DOH – review and approve local rules

Ecology – promulgates its own rules SBOH

Applies to both local and state health State rules are minimum rules for local

health

Washington – local government is where the

action is, where final decisions made

DOH – review and approve local rules

Ecology – promulgates its own rules

34

Philosophy - Permitting Philosophy - Permitting

Ecology

Discharge permits – 5 years, conditions can be

changed, extensive sampling, PH & environment

Performance standards Little technical detail in rules

Health

System Approvals, construction permits Want on-going observations & measurements Conditions typically not changed Historically, prescriptive standards – a lot of

technical detail in rules

Ecology

Discharge permits – 5 years, conditions can be

changed, extensive sampling, PH & environment

Performance standards Little technical detail in rules

Health

System Approvals, construction permits Want on-going observations & measurements Conditions typically not changed Historically, prescriptive standards – a lot of

technical detail in rules

35

Philosophy – Technology Review Philosophy – Technology Review

Ecology

No real up-front verification of technology Depend on intensive monitoring/sampling

Health

Centralized review Level playing field For smaller flows - up-front verification Specific testing protocol Must be on state list

Ecology

No real up-front verification of technology Depend on intensive monitoring/sampling

Health

Centralized review Level playing field For smaller flows - up-front verification Specific testing protocol Must be on state list

36

SBOH rules - 2005 SBOH rules - 2005

Technology reviews Assure good designs

State license Assure good site evaluation Match site’s sensitivity with appropriate levels of

treatment – Treatment Levels (show table)

Design to simplify monitoring/maintenance

Proper repairs of failures Minimum lot sizes – area for installation, nitrogen LHJs – management plans & rules Consistent with land use planning Technology reviews Assure good designs

State license Assure good site evaluation Match site’s sensitivity with appropriate levels of

treatment – Treatment Levels (show table)

Design to simplify monitoring/maintenance

Proper repairs of failures Minimum lot sizes – area for installation, nitrogen LHJs – management plans & rules Consistent with land use planning

37

CTED CTED

Growth management Assumptions – OSS not desirable, not long-term No OSS within GMAs No sewers outside GMAs Version of land use planning by utilities – opposite of way it should be Takes options away from communities Growth management Assumptions – OSS not desirable, not long-term No OSS within GMAs No sewers outside GMAs Version of land use planning by utilities – opposite of way it should be Takes options away from communities

38

Decentralized Technologies Decentralized Technologies

Collection/Transmission Application/Distribution Pretreatment Final Treatment/Dispersal

39

Core Concept Core Concept

P = S + Tns + Ts

Where: P = Pollutant load to be removed by system S = Pollutant removed at the source Tns = Treatment by non-soil components Ts = Treatment by soil

P = S + Tns + Ts

Where: P = Pollutant load to be removed by system S = Pollutant removed at the source Tns = Treatment by non-soil components Ts = Treatment by soil

40

Core Concept Core Concept

We normally depend on the soil to provide the bulk of treatment to sewage We normally depend on the soil to provide the bulk of treatment to sewage

Tns + Ts Pollutant load

(CBOD, TSS, FC, TN)

41

Core Concept Core Concept

As site’s treatment capacity decreases, pretreatment levels must increase. As site’s treatment capacity decreases, pretreatment levels must increase.

Pollutant load

(CBOD, TSS, FC, TN)

Tns + Ts

42

System Selection Strategies System Selection Strategies

Restrictive layer Soil depth

43

System Selection Strategies System Selection Strategies

Adsorption in soil, physical-chemical Phosphorous Nitrification-denitrification, ion-exchange Nitrogen Filtration, predation, inactivation, disinfection Pathogens Aerobic processes Organic material (BOD5) Sedimentation, filtration Suspended solids

Removal Processes Parameter

Adapted from USEPA, 2002

44

In conclusion: In conclusion:

We have huge responsibility to assist small communities We do not do them a favor when we limit the wastewater choices Individual and cluster systems can be viable, long-term alternatives Just like a centralized sewerage system, decentralized systems need on-going O&M We need to understand the technologies to make good choices We have huge responsibility to assist small communities We do not do them a favor when we limit the wastewater choices Individual and cluster systems can be viable, long-term alternatives Just like a centralized sewerage system, decentralized systems need on-going O&M We need to understand the technologies to make good choices

45

Thank You! Thank You! Thank You!