southern kent island, maryland (ski) sanitary project annual...southern kent island, maryland (ski)...

Southern Kent Island, Maryland (SKI)Sanitary Project

National Onsite Wastewater Recycling Association

2017

www.skisewer.com1

Southern Kent Island Sanitary Project

• Project overview

• Problems & challenges faced

• Smart growth considerations

• Climate change & rising sea level “risks”

• Project system

• Phasing & construction status

2

Correct a long-standing public health problem within existing 1950’s

& 60’s-era communities that were developed before modern public

health and land use regulations.

• Affordably

• Growth limits

• Permanent

• Robust

Southern Kent Island Sanitary Project Goal

3

Location Map

Environmentally challenging area!4

Failing onsite septic systems

• 1,518 existing homes

• 1,600 vacant lots of record

80% of existing homes discharging directly into groundwater

Communities situated miles away from public sewer service area

Environmentally sensitive region – 70% of project within

Chesapeake Bay Critical Area

Public concerns about growth from a sewer line extension

Southern Kent Island Sanitary Project Problem

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Small Lot Sizes

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Kent Island Estates

High Groundwater

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High Groundwater and Septic Trenches

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Poorly Drained Soils

9

Public Health and Environmental Issues

• High groundwater

• Soils with poor permeability

• Small lot sizes

3 Strikes and You’re Out!

10

Historical County Efforts

2008 – Retained engineering/planning firm (JMT) to evaluate

options for a public sewer system to serve South Kent Island

2010 – Comprehensive plan adopted reflecting future public

sewer service to SKI communities

2011 – Local Advisory Board concludes that “public sewer

collection and treatment is warranted”

• Limit infill

• Establish an Economic Benefit Premium (EBP)

• Obtain state grants

11

Began regular meetings with MDE & MDP to craft a plan to balance

infill development with project financing and costs to residents

• Bay Restoration Fund

• State revolving loans

Local health department adopts “holding tank policy” for failed septic

system areas

• 7 homes and 2 businesses currently on holding tanks

• 500+ additional homes identified for holding tanks

Smart Growth Considerations

12

Avoid Holding Tanks

Average House:

$200 - $400 per pump out

$7,200 - $8,640 per year

About $600 a month

13

Introduced Lot Consolidation Ordinance #13-24

• Merged adjacent lots under common ownership

• Must conform with existing zoning district NC-20

Final project service area boundaries established

• Denied access force main

• Only offer service to vacant interspersed lots / avoiding

undeveloped blocks of lots from service area

• Vacant lot inventory reduced – from 1,600 down to 632

Appraisal to set EBP range and introduced Special Benefit Resolution

#14-07 to levy project cost

Smart Growth Considerations

14

Lot Consolidation Map

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Lot Consolidation Map

18

Researched and developed public sewer system design concept using Septic

Tank Effluent Pumping (“STEP”)

• Best suited for areas with limited topography

• Simple and efficient design technology

• Low-pressure system

• Easy to retrofill

MDE sponsored legislation HB 11 to change state law, which made BRF funds

eligible for the project

State & County Efforts - Planning

19

Serving the 9 communities at SKI with the sanitary project

will:

• Help prevent future growth

• Provide a cost-effective solution

• Eliminate pathogens

• Provide superior reduction in nitrogen loads

Best Alternative for SKI

20

EXISTING CONDITIONS – Septic Systems NITROGEN LOAD - LBS/YEAR

Septic Systems

940 homes - Critical Area 17,446

113 homes - near a stream 1,311

465 homes beyond the Critical Area 3,236

vacant lots 0

Non-point

1,518 homes - 878 acres 6,895

vacant lots - 327 acres 1,528

About 30,400 lbs/yr TOTAL

Nitrogen Loads – Existing

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FUTURE CONDITIONS – Connect to WWTP NITROGEN LOAD - LBS/YEAR

ENR

1,518 existing homes on ENR and

560 new homes on ENR 4,987

Non-point

1,518 existing homes - 878 acres and

560 new homes - 327 acres 8,158

About 13,100 lbs/yr TOTAL

Nitrogen Loads – Future

22

Existing septic and non-point N loads 30,400 lbs/yr

Future ENR and non-point N loads - 13,100 lbs/yr

Reduction in Nitrogen Loads 17,300 lbs/yr

Reduction in Nitrogen Loads

23

Approval of SKI sewer extension and eligibility for use of BRF funds

and SRL grants

1. Limited to 1518 existing homes and max of 632 infill vacant lots

2. Report new connections annually to MDP

3. Limit treatment capacity to 500,000 gpd

4. No increased capacity for existing non-residential uses

5. Denial of service for any future connection outside of SKI

service area

6. Adopt MD model floodplain ordinance with a 2-foot freeboard

requirement

7. Evaluate climate change vulnerability and outline strategies to

enhance resilience

State Smart Growth Committee

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“Thoroughly assess climate change impact vulnerability

and outline specific strategies for enhancing resilience to

the impacts of sea level rise and coastal flooding.”

Climate Change

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SLR & Coastal Vulnerability Scenarios

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• Infrastructure impacts

– EMS

– Evacuation routes

– Roads

– Schools

– Wastewater facilities

– Water supply

– Residential property/structures

– Commercial property/structures

• Natural resource impacts

– Wetlands

– Critical area

– Agricultural land

Scenarios and Impacts

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Study Area Scenario 1 Scenario 2 Scenario 3

1 0.5% 0.8% 1.1%

2 2.5% 3.7% 5.6%

3 13.7% 22.8% 34.2%

4 11.1% 18.9% 31.9%

Countywide 2.6% 4.1% 6.3%

Percent of Land Impacted

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• Avoid

• Accommodate

• Protect

• Retreat

• Build adaptive capacity

Climate Change Protection Strategies

30

• Identify areas of high vulnerability

• 2014 FEMA flood insurance rate maps have reduced flood

zone compared to prior maps by 313 acres or 70% in SKI

communities

• County floodplain ordinance proposed to increase freeboard

requirement from 1 to 2 feet

• Evaluate changes to zoning

• Application of building code will mitigate future property

damage from flooding

Climate Change Risks Mitigated

31

• Environmental degradation from effluent backwash much greater

with storm surge over individual failing septic systems than over

proposed closed STEP sewer system

• Participate in FEMA’s Community Rating System

• Employ CRS activities

• Evaluate feasibility of land acquisition of vulnerable properties


32

• Plan for mobilizations of EMS services

• Kent Island can be evacuated within 24 hours

• DES will begin advanced notifications 7 days prior to a potential

threat that may result in an evacuation

• Reverse notification system “Everbridge” and other media

sources will be used to notify and provide frequent updates

• EOC will be activated and a decision to evacuate will be made at

least 2 to 3 days prior to a potential threat


33

System Alternatives

Selecting the Right Sewer System

34

• Vacuum Sewers (majority of connections in SKI are vacuum

sewers)

• Gravity Sewers

• Grinder Pump Low Pressure Sewers

• Septic Tank Effluent Pumping (STEP) Low Pressure Sewers

Choosing a System Type


35

Vacuum Sewers

• Vacuum Pit at each house

• Solids handling vacuum sewer mains, laid below frost line in saw-tooth pattern

• Wastewater collected at Central Vacuum Pump Stations

• Sewage is then pumped to WWTP

• Little to no storage in Vacuum Pit –problems in pit are an emergency

• Vacuum Pump Stations are expensive to build, require property purchase and regular maintenance



36

Gravity Sewers

• 4” or 6” lateral pipe from home to gravity sewer

collection main

• Gravity sewer collection main is minimum 8”

diameter, typically 8’ to 15’ or deeper below

grade, laid at a constant downslope

• Manholes required throughout collection system

• Large Main Pumping Stations required

• Gravity sewers are not water tight (subject to

infiltration and inflow (I/I))

• Construction is very expensive and highly

disruptive

• Regular maintenance required at Main

Pumping Stations and to control I/I



37

Grinder Low Pressure Sewers

• Grinder Pump Basins at each house

• Grinder Pump grinds solids, fats, oils and greases into a slurry

• Grinder pump then pumps slurry through small diameter low pressure sewer mains to WWTP

• Must maintain minimum scour velocity to keep main unclogged and free flowing

• Little to no storage in Grinder Pump Station – problems in pump station are an emergency

• Grinder pumps and cutters require maintenance

Septic Tank Effluent Pumping (STEP) Low Pressure Sewer System


38

Project SystemSTEP System On-lot Component Overview

• Solids are retained on site

• Minimum of 24-hours of storage

in the interceptor tank

• Only clear septic tank effluent is

pumped to the treatment plant

• Low installation costs

• Low energy use

• Simple to operate and maintain


• Watertight, 1,000 or 1,500 Gallon Septic

Tank

• Effluent Pumping package

– Pump vault

– High-head effluent pump

– filter cartridge

– Float assembly

– Discharge assembly

– Splice box

• Control Panel

Seamless Concrete Tanks

41

STEP Biotube & Pump Assembly

42


High-Head Effluent Pump

• Non-corroding stainless steel

• Typically 115V

• Lightweight; under 30 pounds

• Long life; 20 to 30 years

• Easy to maintain

• 10-year warranty


High-Head Effluent Pump Curve

Project SystemSTEP System Low Pressure Sewer Component Overview

• Shallow burial depth

• Laid to contour of land

• Low minimum velocities

• No oversized designs (due to little I/I)

• Low operation and maintenance costs

EDUs QpPipe Size,

Inches

Head Loss,

ft/1000 ft

10 20 1 1/4 35 +

100 65 2 54 +

500 265 4 32 +

1000 515 6 16 +

• Uses directional drill technology (HDD)

• Closed system minimizes I & I

• Eliminates need for intermediate pump stations

• Provides emergency storage during power outages

• Service call issues are minor (isolated to individual home vs. hundreds of

homes)

• Easy to pinpoint and correct problems

• Pumps are economical, yet robust

• Use of seamless concrete tanks

• Adaptable to varying site conditions

• Can be integrated into existing sewer infrastructure

• Abuses stay in septic tank

Project SystemSTEP System Advantages

46

• Thousands of Orenco

Effluent Sewers have

been installed for

Municipal and

Commercial projects in

virtually every U.S. state

and Canadian province.

• Systems with up to ~

4,000 connections

Project SystemResearch into Other Communities with STEP Systems

Project SystemResearch into Other Communities with STEP Systems

• 35+ years of documented system performance

– Glide, OR, 1,100+ connections, installed in 1980

• Officials at Queen Anne’s County visited similarly sized systems

– Yelm, WA, 1,100; Lacey, WA, 4,000+; Montesanto, WA, 2,000; Coborg, OR, 400

• Other Regional examples and number of connections

– Northern: Southwest Barry County, MI, 1000+

– Mountain: Missoula, MT, 2000

– Central: Bucyrus, KS, 80

– Southwest: Penn Valley, CA, 240

– Southeast: Ariton, AL, 340

– Northeast: Hillsdale, NY, 130

– Northwest: Camas, WA, 2,900

Typical STEP Tank Install

49

Phase 1 - Kent Island Estates & Romancoke

Construction contracts awarded August 2016

Construction is now underway!

• STEP systems contract #16-01

• Transmission main contract #16-02

• Community mains contract #16-03

Community public outreach continuing

SKI Current Status

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Construction in Progress

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Final STEP Tank Install

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HDD under US 50


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HDD under US 50


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HDD under US 50


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• Estimated total cost of infrastructure: $50 million

• Phase 1 cost: $32 million

• State Revolving Loan with 30-year term

• Assessments will be levied as work is completed

• BRF offsets expense to existing homes: $10,000 per home

• Vacant lots pay EBP charge: $25,600

• Final cost to homeowners: $100/month

• Final cost to vacant lot owners: $159/month + allocation fee with an

option to defer for up to 10 years

Financial Parameters

59

Queen Anne’s County Department of Public Works

Todd R. Mohn, PE

Director

[email protected]

www.skisewer.com

60

Julie Barown, P.E.

Northeast Regional Engineer

Orenco Systems, Inc.

[email protected]

www.orenco.com

61

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