Southern Kent Island, Maryland (SKI) Sanitary Project

Transcription

1 Southern Kent Island, Maryland (SKI) Sanitary Project National Onsite Wastewater Recycling Association

2 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

3 Southern Kent Island Sanitary Project Goal 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 3

4 Location Map Environmentally challenging area! 4

5 Southern Kent Island Sanitary Project Problem 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 5

6 Small Lot Sizes 6

7 High Groundwater Kent Island Estates 7

8 High Groundwater and Septic Trenches 8

9 Poorly Drained Soils 9

10 Public Health and Environmental Issues High groundwater Soils with poor permeability Small lot sizes 3 Strikes and You re Out! 10

11 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

12 Smart Growth Considerations 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 12

13 Avoid Holding Tanks Average House: $200 - $400 per pump out $7,200 - $8,640 per year About $600 a month 13

14 Smart Growth Considerations 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 14

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17 Lot Consolidation Map 17

18 Lot Consolidation Map 18

19 State & County Efforts - Planning 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 19

20 Best Alternative for SKI 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 20

21 Nitrogen Loads Existing EXISTING CONDITIONS Septic Systems NITROGEN LOAD - LBS/YEAR Septic Systems 940 homes - Critical Area 17, homes - near a stream 1, homes beyond the Critical Area 3,236 vacant lots 0 Non-point 1,518 homes acres 6,895 vacant lots acres 1,528 About 30,400 lbs/yr TOTAL 21

22 Nitrogen Loads Future 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 acres and 560 new homes acres 8,158 About 13,100 lbs/yr TOTAL 22

23 Reduction in Nitrogen Loads Existing septic and non-point N loads Future ENR and non-point N loads 30,400 lbs/yr - 13,100 lbs/yr Reduction in Nitrogen Loads 17,300 lbs/yr 23

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25 State Smart Growth Committee 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 25

26 Climate Change Thoroughly assess climate change impact vulnerability and outline specific strategies for enhancing resilience to the impacts of sea level rise and coastal flooding. 26

27 SLR & Coastal Vulnerability Scenarios 27

28 Scenarios and Impacts 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 28

29 Percent of Land Impacted Study Area Scenario 1 Scenario 2 Scenario % 0.8% 1.1% 2 2.5% 3.7% 5.6% % 22.8% 34.2% % 18.9% 31.9% Countywide 2.6% 4.1% 6.3% 29

30 Climate Change Protection Strategies Avoid Accommodate Protect Retreat Build adaptive capacity 30

31 Climate Change Risks Mitigated 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 31

32 Climate Change Risks Mitigated 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

33 Climate Change Risks Mitigated 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

34 Selecting the Right Sewer System System Alternatives 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 34

35 Selecting the Right Sewer System Choosing a System Type 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 35

36 Selecting the Right Sewer System Choosing a System Type 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 36

37 Selecting the Right Sewer System Choosing a System Type 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 37

38 Selecting the Right Sewer System Septic Tank Effluent Pumping (STEP) Low Pressure Sewer System 38

39 Project System STEP 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

40 Project System STEP System On-lot Component Overview 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

41 Seamless Concrete Tanks 41

42 STEP Biotube & Pump Assembly 42

43 Project System STEP System On-lot Component Overview 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

44 Project System STEP System On-lot Component Overview High-Head Effluent Pump Curve

45 Project System STEP 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 Qp Pipe Size, Head Loss, Inches ft/1000 ft /

46 Project System STEP System Advantages 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 46

47 Project System Research into Other Communities with STEP Systems 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

48 Project System Research 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, 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

49 Typical STEP Tank Install 49

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51 SKI Current Status 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 51

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53 Construction in Progress 53

54 Construction in Progress 54

55 Final STEP Tank Install 55

56 Construction in Progress HDD under US 50 56

57 Construction in Progress HDD under US 50 57

58 Construction in Progress HDD under US 50 58

59 Financial Parameters 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 59

60 Queen Anne s County Department of Public Works Todd R. Mohn, PE Director tmohn@qac.org 60

61 Julie Barown, P.E. Northeast Regional Engineer Orenco Systems, Inc. 61