SANDY POINT SEWAGE TREATMENT PLANT UPGRADE: PIEVC CLIMATE CHANGE VULNERABILITY ASSESSMENT

Transcription

1 Environment SANDY POINT SEWAGE TREATMENT PLANT UPGRADE: PIEVC CLIMATE CHANGE VULNERABILITY ASSESSMENT Municipality of the District of Shelburne, Nova Scotia

2 PIEVC Process at Pre-Design Presentation Outline: Existing System Description New Plant Design Criteria Technology and Site Selection PIEVC Process Results Project Definition Data Gathering & Sufficiency Risk Assessment Engineering Analysis Conclusions & Recommendations

3 Existing Extended Aeration STP 30,000 USgpd capacity constructed in 1969 Overloaded and out of compliance with NSE discharge limits Wet weather flows affecting plant performance

4 New Plant Design Criteria Expansion of Industrial Park (add l 29 acres) 5,000 USgpd Average Daily Flow 100,000 USgpd Maximum Daily Flow 350,000 USgpd Organic Loading Rate kg/d Solids Loading Rate kg/d

5 Design Criteria Continued Effluent Discharge Limits (MWWE open coastline) BOD 5 25 mg/l TSS 25 mg/l Fecal Coliform 200 MPN / 100 ml Secondary Level of sewage treatment Modular growth/expansion Future plan for servicing residences of Sandy Point Road (Industrial Park to Canadian Armed Forces Base) Option for receipt of septage

6 Technology Selection: Lagoon Simple to construct, operate and maintain Often only part time supervision required Preferred option for systems prone to peak (I&I) flows Reliability (effluent discharge limits) Couple with wetland? Sludge management horizon (~10 to 20 yrs) Easily accommodate septage receiving station Expandable in cells

7 Site Selection #3 #2 #1

8 Site Selection

9 Flow Diagram

10 PIEVC Process Integrated with Design Project Lifecycle Pre-Design Specification Site Selection Technology Selection PIEVC Detailed Design Tendering Construction Operation PIEVC Process Project Definition Data Gathering & Sufficiency Risk Assessment Engineering Analysis Conclusions & Recommendations

11 Project Definition - Infrastructure Infrastructure Categories: Administration Conveyance System Treatment System Maintenance Transportation End Users Administration includes engineering, operations, public works and support staff Conveyance system: Existing gravity collection system built with upgrades in 2002 Existing and proposed pumping stations Treatment system (lagoons, process building) Maintenance Transportation (septage, access to systems) End Users (residential, commercial, industrial, institutional)

12 Project Definition Climate Parameters Climate Parameters: Precipitation as rain Precipitation as snow Sea level elevation Wind Speed Frost Fog Storm surge Ice Temperature Precipitation as rain: Greater than 100mm of rain over a three (3) day period Precipitation as snow: Snow Frequency - No. of days with snowfall amounts greater than 10 cm Snow Accumulation Five (5) or more days with snow depth greater than 20cm Blizzard Eight (8) or more days with blowing snow Rain on Snow Ten (10) or more days where rain falls on snow Sea Level Elevation

13 Project Definition Climate Parameters Climate Parameters: Precipitation as rain Precipitation as snow Sea level elevation Wind Speed Frost Fog Storm surge Ice Temperature Wind Speed: Winds or Downburst greater than 80.5 km/hour Hurricane winds (increased frequency) Frost: Freeze/Thaw, Frost Penetration Depth Fog: Visibility Storm Surge Ice: Ice storm, hail storm, ice accretion, sea ice Temperature: No. of days with minimum temperature below -30.0ºC No. of days with maximum temperature exceeding 35.0ºC

14 Climate Data Temperature and Precipitation Minimum Temperature Maximum Temperature Precipitation Amount Tri-decade 2020s 2050s 2080s 2020s 2050s 2080s 2020s 2050s 2080s Units ºC ºC ºC ºC ºC ºC % % % Greenwood Kentville Shearwater Yarmouth For current climate (1961 to 1990) the greatest three (3) day total rainfall is 87mm For projected climate (2071 to 2100) the greatest three (3) day total rainfall is projected to increase to 116mm

15 Climate Data Storms, Storm Surges and Sea level Rise Ultimately, high water levels result from a combination of the specific meteorological event, geographic location of event, sea level rise, storm surge, sinking land, and wave run-up Sea Level Elevation average sea level rise globally Crustal subsidence (sinking land) Frost and Freeze/Thaw cycling predicted to decrease

16 Storm Surge (40 year return) in Atlantic Canada

17 Extreme Rainfall Statistics Atlantic Canada

18 Climate-Infrastructure Interactions Total of 45 infrastructure components identified Total of 24 Climate events identified Of 1080 possible interactions, 404 were identified as having potential consequences Performance response types considered: Structural Design Functionality Watershed, Surface Water, and Groundwater Operations, Maintenance, and Materials Performance Emergency Response Insurance Considerations Policy Considerations Social Effects

19 Risk Assessment R = P x S R: Risk P: Probability S: Severity Engineering team conducted preassessment of risk using matrix Modified workshop process to prioritize interactions discussed and to rank interactions as High/Medium/Low risk 14/404 interactions were High Risk 111/404 interactions were Medium Risk

20 Risk Assessment High Risk Interactions Infrastructure Component Admin / Operations Personnel Conveyance System Existing Gravity Collection Sanitary MH Sanitary Gravity Mains Pipe Connection & Fittings Existing Pumping Station Power Supply New Pumping Station Power Supply Power Supply Treatment System New Treatment System Ocean Outfall Process Building Structure UV Disinfection Power Supply End Users End Users (Res., Ind., Inst.) Hurricane Event Heavy (Intense) Rain Heavy (Intense) Rain Heavy (Intense) Rain Hurricane Event Ice Storm Event Hurricane Event Ice Storm Event Sea Level Elevation Hurricane Event Sea Level Elevation Hurricane Event Ice Storm Event Hurricane Event Climate Variable

21 Risk Assessment Participants identified opportunities for mitigation and adaptive capacity: The majority of interactions related to power supply, communications and access to infrastructure components during extreme climate events SCADA complete with UPS and backup power system requirements identified Shut-off for existing pumping station when seawater ingress experienced Planned increases in maintenance due to climate events Installation of weather station at the plant site

22 Engineering Analysis Much of the data required for the Engineering Analysis did not exist or was difficult to obtain Professional judgment and experience was employed where data was not available For the thirty-five (35) components for which potential vulnerabilities were identified 21 remedial engineering actions recommended 4 management actions being recommended

23 Recommendations Administration and Operations Management action required: Develop and maintain OH & S policy and/or Standard Operating Procedures (SOPs) to address safety of personnel during extreme climatic events Maintenance Management action required: Develop and maintain OH & S policy and/or Standard Operating Procedures (SOPs) to address and prioritize equipment rehabilitation/repairs during extreme climatic events

24 Recommendations Collection System Additional study or data required: CCTV inspection of existing collection system to identify possible I & I sources Remedial engineering or operation actions required: Develop program for the reduction of I & I Develop standards or adopt Standard Specifications for Municipal Services for all repairs and/or replacement of existing collection system

25 Recommendations Existing / New Pumping Stations Remedial engineering or operation actions required: Provide permanent back-up power at the new pumping station Provide temporary back-up (portable genset receptacle) power at the existing pumping station Provide salinity sensor and/or high-high level float to disable pump stations in the event of saltwater intrusion or storm surge Provide radio based SCADA / telemetry system to communication disruptions during extreme events (locate mast to avoid tree fall damage)

26 Recommendations Sewage Treatment Plant Remedial engineering or operation actions required: Ensure adequate separation (c/w factor of safety) between high water tidal level and elevation of serpentine weir for UV disinfection equipment (coordinate sizing of ocean outfall as required) Provide magnetic type flow meter at STP to ensure continuous high resolution flow monitoring (can be used to evaluate effectiveness of I & I program) Provide weather station at STP for collection of site specific climate data and NSE reporting purposes Ensure STP super structure meets/exceeds code for hurricane resistance Provide radio based SCADA / telemetry system to communication disruptions during extreme events (locate mast to avoid tree fall damage)

27 Recommendations Transportation Management action required: Develop and maintain OH & S policy and/or Standard Operating Procedures (SOPs) to cease operation of non-essential elements (septage receiving station, etc.) of the treatment plant during extreme climatic events. Restrict access to the treatment plant to essential personnel.

28 PIEVC at the Design Stage This project is small, and PIEVC was implemented at the pre-design stage: The Protocol as presented was a useful complement to the pre-design process and assisted in site selection, technology selection and design of components. It was difficult to assess the detailed system components at such an early stage in the design process. The Protocol is currently one-size-fits-all but if was flexible enough to adapt it to fit our purpose

29 Questions?