Everything You Never Wanted to Know About

Cesspools and Onsite Wastewater

Hawaii Association of Conservation Districts

2008 Water Quality Conference

March 24-25, 2008

Hudson Slay

Hawaii Department of Health

Polluted Runoff Control Program

Overview

• Cesspools and other types of onsite wastewater disposal systems

• Water quality impacts of these systems

• Existing mechanisms to address cesspools and onsite wastewater issues

• Elements of DOH Strategy

• Next Steps

Terms/Acronymns

• Large Capacity Cesspool (LCC)

• Individual sewage disposal system (ISDS)

• Individual wastewater system (IWS)

• Onsite sewage disposal system (OSDS)

• Onsite wastewater treatment system (OWTS)

• Conventional system

• Alternative system

• Alternative/Innovative system (AI)

What is a Cesspool?

What is a Cesspool?

cover (sometimes at ground surface or buried)

Influent (waste)from building(s)

Brick, stone, concrete Block, Ring, or Precast Chamber, or other sidewall material, with Open Joints

ExcavationFluid Level

Sludge Accumulation

Leachate

water table

Backfill Material

Typical Cesspool Design

Issues with Cesspools

• Solids settle to the bottom, floating grease and scum collect at the top, and liquid seeps into the ground through the bottom and the side of the cesspool

• Provides minimal treatment of human sewage

• Impact ground and surface waters• Cesspools pose a very serious hazard due to

cave-ins or collapse

Conventional Systems

Alternative Systems

Alternative or innovative systems feature components and processes designed to promote degradation and/or treatment of wastes through biological processes, oxidation/reduction reactions, filtration,evapotranspiration, and other processes.

Some examples: sand/media filters, continuous flow-suspended growth aerobic system, fixed film processes, low-pressure drip applications, sequenced batch reactor systems, packed bed reactors

These systems are often used or required:– near nutrient-sensitive waters– high densities of existing conventional systems – highly permeable or shallow soils – shallow water tables– large rocks or confining layers – poorly drained soils

Do they work?

• When properly planned, designed, installed, operated, and maintained onsite systems can effectively remove or treat contaminants such as pathogens, biochemical oxygen demand (BOD), and nutrients in human sewage.

• Detrimental impacts from on-site systems can occur:

1. when sited in sensitive ecological areas (such as wellhead protection zones, near nitrogen/phosphorus limited waters, or near beaches or shellfish habitat) or

2. when installed at densities that exceed the hydraulic and hydrologic assimilative capacities of regional soils and aquifers.

Causes of Failure

SYSTEM BOD mg/L

TSS mg/L Total Nitrogen mg/L

Total Phosphorusmg/L

Fecal ColiformsPer 100 mL

Comments

Cesspool 100-400 100-400 15-90 5-20 106 - 108

Septic Tank w/Absorption Trenches

< 30 4 1 < 2 13

Septic Tank w/Absorption Beds

< 30 4 1 < 2 13

Septic Tank w/Elevated Mounds

< 30 < 20 < 15 < 2 13

Water Reuse < 30 mg/L < 30 mg/L No specs. No specs <23

Treatment Efficiency

Source: Onsite Wastewatear Treatment Survey and Assessment, UH WRRC

Mechanisms to Address Onsite Wastewater Issues

• Safe Drinking Water Act Underground Injection Control (UIC) ban of Large Capacity Cesspools

• Department of Health, HAR Chapter 11-62

• Hawaii’s Coastal Nonpoint Pollution Control Program

• Ocean Resources Management Plan

Ban on Large Capacity Cesspools

• SDWA Underground Injection Control (UIC)

• Federal Regulation December 7, 1999

• Bans the construction of new cesspools after April 5, 2000

• Required closures of all LCCs by April 5, 2005

What are Large Capacity Cesspools?

• ResidentialProperties-If serves multiple dwellings – Multiple Homes– Apartment Bldgs/Condos– House with an Ohana or

Cottage;

• Dwelling Definition – Sleeping area– Food preparation area– Bathroom

• Non-Residential:– Capacity to serve 20 or more

persons per day ANY time

Single family homes and individual cesspools are exempt

EPA Large Capacity Cesspools

Approximately 3,000 LCCs in Hawaii:

• ~ 25% have been closed

• ~ 25% consent agreement/final order

• ~ 25% on voluntary closure schedule

• ~ 25% unaddressed

Source: Rebecca Tuden, US EPA Region 9

Individual Wastewater System Approved Statewide1992 to 2006

0500

10001500200025003000350040004500

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

Year

No.

of I

WS

0

500

1000

1500

2000

No. o

f IW

S

Big Island Maui Kauai Oahu

IWS Approved by Islands from 4/30/05 to 4/30/06

DOH Wastewater Branch

•Hawaii Administrative Rules, Chapter 11-62

Approval Process for an Individual

Wastewater System (IWS)

IWS Report &Construction Plans

Approval to UseLetter from DOH

Approval to ConstructLetter from DOH

Construction Inspection

Cesspools Severely Restricted or Prohibited in Critical Wastewater Disposal Areas

(CWDA)No Cesspools Allowed in Oahu & Kauai

Owner’s Certification Form

‘…IWS will be inspected, operatedand maintained….’

‘…to certify upon saleor transfer…shall bindthe new owners to the operation and maintenanceprovisions…’

Hawaii’s Coastal Nonpoint Pollution Control Program

Onsite Disposal Systems Management Measures

New Onsite Disposal Systems 1. Ensure that new Onsite Disposal Systems (OSDS) are located, designed,

installed, operated, inspected, and maintained to prevent the discharge of pollutants to the surface of the ground and to the extent practicable reduce the discharge of pollutants into ground waters that are closely hydrologically connected to surface waters.

2. Direct placement of OSDS away from unsuitable areas. 3. Establish protective setbacks from surface waters, wetlands, and

floodplains for conventional as well as alternative OSDS. 4. Establish protective separation distances between OSDS system

components and groundwater which is closely hydrologicallyconnected to surface waters. The separation distances should be based on soil type, distance to ground water, hydrologic factors, and type of OSDS;

5. Where conditions indicate that nitrogen-limited surface waters may be adversely affected by excess nitrogen loadings from ground water, require the installation of OSDS that reduce total nitrogen loadings by 50 percent to ground water that is closely hydrologically connected to surface water.

Onsite Disposal Systems Management Measures

Operating Onsite Disposal Systems Management1. Establish and implement policies and systems to ensure that existing

OSDS are operated and maintained to prevent the discharge of pollutants to the surface of the ground and to the extent practicable reduce the discharge of pollutants into ground waters that are closely hydrologically connected to surface waters.

2. Inspect OSDS at a frequency adequate to ascertain whether OSDS are failing;

3. Consider replacing or upgrading OSDS to treat influent so that total nitrogen loadings in the effluent are reduced by 50 percent. This provision applies only: where conditions indicate that nitrogen-limited surface waters may be adversely affected by significant ground water nitrogen loadings from OSDS, and where nitrogen loadings from OSDS are delivered to ground water that is closely hydrologicallyconnected to surface water.

Strategy to Address OSDS Inspections

• Attempt to utilize existing program tools

• Insure that effort benefits multiple programs (TMDLs, wastewater, drinking water, polluted runoff control)

• Focus effort where there are impacts/potential impacts to drinking water sources, streams and coastal waters to maximize limited resources

Elements of Strategy

• Water quality monitoring• Scanned cesspool cards• Wastewater Inventory• Efforts by UH Water Resources Research

Center • Possible changes to HAR Chapter 11-62

Water Quality Monitoring

• DOH Monitoring data used to identify potential problems with onsite wastewater systems and trigger ‘inspection’

• If bacteria standard is exceeded a watershed survey is initiated to determine possible sources

• May result in site specific sanitary surveys to link system-water quality problem

• DOH working with USGS to expand monitoring toolbox by using different tracers

Cesspool card

Site drawing

TMK # Image File name

Wastewater Inventory

Central Sewer

Individual Wastewater Systems

Cesspools

DRAFT

DRAFT

DRAFT

DRAFT

UH Water Resources Research Center Assistance

1. Onsite wastewater treatment survey and assessment (still draft)

2. Effort to determine risk posed by OSDS on Oahu and develop inspection protocols (April 2008)

DRAFT DRAFT

Risk Posed by OSDS

Will be based upon risk to drinking water wells, streams, and near shore waters

OSDS risk shall include:• density of OSDS systems in a capture zone, watershed or within a two

(2)-year time of travel to the shoreline (based on groundwater velocity);• Depth to the water table• Groundwater recharge rate and aquifer permeability• Distance to a drinking water well, stream or nearshore water;• Rainfall rate;• Soil organic carbon, dominant particle size, taxonomy, and other soil

data;• Type and Load of existing OSDS• Position in flood zones

Inspection Protocols

• Develop and establish an inspection protocol(s) for onsite sewage disposal systems (“OSDS”)

• Initial focus will be on OSDS impact to sources of drinking water

• Establish a frequency or an event that will trigger an inspection

• Draft appropriate documentation to support the inspection program

What else is needed?

• Resources to enforce existing rules• Implementation and refinement of OSDS strategy• ‘Direct’ inspection requirement? (e.g., point of sale

inspections)• Tax incentives to upgrade individual cesspools?• Additional OSDS education regarding appropriate

operation and maintenance• Sharing inventory information for use by other

stakeholders (counties, watershed groups, etc)

Helpful Links and Contacts

• Department of Health Wastewater Branchhttp://hawaii.gov/health/environmental/water/wastewater/forms.htmlPhone: 586-4294

• Environmental Protection Agencyhttp://www.epa.gov/owm/septic/pubs/septic_guidelines.pdfhttp://www.epa.gov/owm/onsitehttp://www.epa.gov/owm/septic/pubs/onsite_handbook.pdf

Large Capacity Cesspool compliance informationhttp://epa.gov/region09/water/groundwater/uic-hicesspools.htmlToll Free: 1-866-EPAWEST

Contact Information

Hudson Slay

hudson.slay@doh.hawaii.gov

586-4309