sandy point sewage treatment plant upgrade: pievc … · vulnerabilty assessement david trudel,...

SANDY POINT SEWAGE TREATMENT PLANT UPGRADE: PIEVC CLIMATE CHANGE VULNERABILTY ASSESSEMENT

David Trudel, P.Eng. CBCL Limited

Climate Change Adaptation and Infrastructure 2016 – Moncton, NB

Environment

http://www.engineerscanada.ca/

PIEVC IN A SMALL COMMUNITY: PRE-DESIGN

Presentation Outline:

• Community Profile

• Description of Existing System

• Design Criteria

• PIEVC

• PIEVC at Pre-Design Stage

• Recommendations for PIEVC in Small Communities

• Ideas for Implementation


MUNICIPALITY OF THE DISTRICT OF SHELBURNE, NS

Community Profile:

• Population – 4,408

• Rural, coastal community in southwest NS (1,808.5 km2)

• Declining population, low population density dispersed along coast

• Established in 1885, one of five municipal units in Shelburne County


MUNICIPALITY OF THE DISTRICT OF SHELBURNE, NS


DESCRIPTION OF EXISTING SYSTEM

Extended Aeration STP:

• Constructed in 1969

• 30,000 USgpd Capacity

• Overloaded, not in compliance with NSE discharge criteria

• Wet weather flows affecting plant performance


DESIGN CRITERIA

Sewage Treatment Plant Upgrade:

• Expansion of Industrial Park (add’l 29 acres)

• 5,000 Usgpd

• Average Daily Flow – 100,000 USgpd

• Maximum Daily Flow – 350,000 USgpd

• Secondary Treatment

• Modular Growth

• Industrial Park / Sandy Point Road

• Option of Receipt of Septage


PIEVC

Public Infrastructure Engineering

Vulnerability Committee (PIEVC):

• Created August 2005

• Co-funded by NRCan & Engineers Canada

• Committee developed the PIEVC Protocol, a formalized process to assess climate risks to infrastructure

• Goal - ensure that decision makers always consider climate change as an integral part of planning, designing, constructing, operating, maintaining and rehabilitating infrastructure


PIEVC

Project Lifecycle:

• Pre-Design

• Design Criteria

• Site Selection

• Technology Selection

• PIEVC

• Detailed Design

• Tendering

• Construction

• Operations


• PIEVC

• Project Definition

• Data Gathering & Sufficiency

• Risk Assessment

• Engineering Analysis

• Conclusions & Recommendations

DATA GATHERING & SUFFICIENCY

Temperature and Precipitation:

• 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



Storms, Storm Surges & Sea Level Rise:

• Ultimately, high water levels result from a combination high tides, sea level rise, storm surge, sinking land, and possibly wave run-up

• Sea Level Elevation:

• 40 – 132 cm average sea level rise globally

• Crustal subsidence (sinking land) 10 – 15 cm in 100 years

• Frost and Freeze/Thaw cycling predicted to decrease



Storm Surge (40 year return) - Atlantic Canada



Extreme Rainfall Statistics – Atlantic Canada


VULNERABILITY (RISK) ASSESSMENT

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



Methodology:

• Engineering team conducted pre-assessment of risk using matrix

• Limited resources for workshop:

• 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


R = P x S

R: Risk

P: Probability

S: Severity


Workshop:

• Participants identified opportunities for mitigation & adaptive capacity for high risk interactions: • The majority of interactions related to power supply,

communications & access to infrastructure 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


ENGINEERING (INDICATOR) ANALYSIS

Methodology:

• Calculate the projected total load/capacity of the infrastructure:

• Definitions

• Direct Measurements

• Engineering Calculations

• Assumptions based on Professional Judgement


ENGINEERING (INDICATOR) ANALYSIS

• Much of the data required for the Engineering Analysis did not exist or was difficult to obtain

• Pre-design stage

• Limited climate data available

• Professional judgment and experience were used 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


RECOMMENDATIONS

Summary:

• Reduce I&I into the collection system

• Install stand-by power at pumping stations

• Ensure process building meets code for hurricane resistance

• Install radio communications system at the pumping stations and process building

• Install high level pump shutoffs at the existing pumping station


RECOMMENDATIONS

Summary:

• Install a bypass on the grit removal system

• Implement a policy to protect staff from hurricanes, storm surges and ice storms

• Discuss safe conditions for deliveries from septage hauling companies

• Adjust scheduling to accommodate required maintenance


CONSTRUCTION

New STP Constructed 2011-12


CONSTRUCTION

Elevation Above Chart Datum


PIEVC PROCESS AT PRE-DESIGN STAGE

Summary:

• Project was small - PIEVC implemented at the Pre-Design stage:

• Protocol as presented was a useful complement to the Pre-Design process and assisted in site selection, technology selection and design of components

• Difficult to assess the detailed system components at such an early stage in the design process

• Protocol is currently ‘one-size-fits-all’ but it was flexible enough to adapt to fit project


PROJECT UPDATE

• Implemented stand-by power & dialer system for high level alarms at PS’

• Inspected collection system - identified I&I issues to be addressed

• Industrial Park servicing completed 2013-14

• New 80-unit seniors housing complex connected to STP

• SRS installed & commissioned in August 2013 (Volumes < 1% of plant throughput)

• New STP is much more resilient to heavy precipitation events and power outages

• PIEVC results used to supplement MCCAP


QUESTIONS?


sandy point sewage treatment plant upgrade: pievc … · vulnerabilty assessement david trudel,...

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