Volume Reduction in the Regional District of Nanaimo s Sanitary Sewers

Transcription

1 Volume Reduction in the Regional District of Nanaimo s Sanitary Sewers Andy Bell Infrastructure Engineer AECOM Canada Inc Vancouver, CANADA Andrew.Bell@aecom.com

2 Introduction The Ministry of Environment s (MoE) long term goal is to achieve zero pollution To reduce pollution from liquid wastes, the MoE requires discharging communities to prepare Liquid Waste Management Plans Volume reduction in sewers is one aspect of this plan Specifically, the MoE requires consideration of reducing inflow and infiltration flows/volumes in sanitary sewers, which can upset wastewater treatment process and cause sewage spills to the environment As the RDN is responsible for sewage disposal in the District it has chosen to follow MoE guidelines on developing a LWMP

3 Presentation Outline RDN sanitary infrastructure Understanding sanitary sewer flows problems and costs Practices for reducing sanitary sewer flows I&I in RDN and municipal sanitary systems Reducing sanitary sewer flows in the RDN Funding opportunities to reduce sanitary sewer flows Discussion

4 RDN Sanitary Infrastructure

5 RDN Infrastructure 4 Pollution Control Centers 4 Trunk Sewer Networks 19 Pump Stations 5 small sanitary collection systems Several flow measurement stations

6 Summary of PCCs and Service Areas Pollution Control Centre Greater Nanaimo (GNPCC) French Creek (FCPCC) Nanoose (NPCC) Duke Point (DPPCC) Community Served The Greater Nanaimo Service Area* The District of Lantzville** The Town of Qualicum Beach The City of Parksville The Surfside Sanitary Sewer Service Area*** French Creek Sewer Service Area*** The Barclay Crescent Sewer Service Area*** The Pacific Shores Sanitary Sewer Service Area*** The Fairwinds Sanitary Sewer Service Area*** Duke Point Service area* *Collection system operated by the City of Nanaimo **Only a small area of Lantzville has recently received sewer services *** Collection system operated by the RDN

7 Understanding Sanitary Sewer Flows Problems and Costs

8 Sanitary sewer flows Sewage flow comprises 3 parts: 1. Wastewater 2. Inflow 3. Infiltration High volume can cause pollution

9 Common Sources of I&I It is recognized that up to 50% of I&I can come from private properties The property line is typically the boundary between owner and sewer operator responsibilities

10 Inflow & Infiltration (I&I) Problems and Costs Pollution pollution control centre hydraulically overloaded - sludge washouts or raw sewage overflow sewer hydraulically - overloaded overflows Pollution events cost money to clean up and can have far reaching social and environmental consequences High volumes equal unnecessary power, chemical and labour costs to the RDN, which are passed back to municipalities Additional risks Infiltrating pipes more likely to have operational problems In certain soil conditions, infiltration can lead to the loss of soil particles and the formation of voids or sinkholes with sometimes disastrous consequences

11 A watermain break washes soil into an infiltrating sewer resulting in a sink hole (Ontario)

12 Identifying I&I Measure flows in sewers -Correlate rainfall and high sewer flow -Look for high nightime flows -Estimate flows based on connections and property use

13 Identifying Inflow Sources 1. Vapour (smoke) tests 2. Dye tests

14 Identifying Infiltration Sources 3. CCTV

15 Identifying Iinfiltration Sources 4. Manhole Inspection

16 Inflow and Infiltration Economics

17 BC s Municipal Sewage Regulation state The discharger must ensure that no person allows I&I so that the maximum average daily flow exceeds 2.0 times ADWF to occur during storm or snowmelt events with less than a 5-year return period. 2.0 x ADWF ADWF

18 Practices for reducing sanitary sewer flows

19 Reducing Inflow

20 Examples of Reducing Inflow

21 Examples of soak-away and absorbent landscapes Rainwater management to be covered in a December Discussion Paper

22 Examples of Reducing Infiltration

23 Reducing Wastewater Flow (inside buildings) Installation of water efficient toilets, washing machines, faucets & showerheads Fixing leaks (toilet flappers) Water audit kits (include cistern bags for toilets, dye tablets, plumbing fixtures) The RDN s Watersmart initiative actively promotes such activities

24 I&I in RDN and Municipal Sanitary Systems

25 RDN Trunk Systems No significant I&I issues in RDN infrastructure have been identified CCTV inspections show insignificant I&I Manholes leaks fixed and lids sealed Other known problems fixed However, I&I from the Greater Nanaimo area has been seen to overwhelm Departure Bay Pump Station during extreme weather events RDN landfill site has the potential to significantly increase I&I, exacerbating the Departure Bay Pump Station issue I&I from the French Creek area has been seen to overwhelm Lee Road Pump Station during extreme weather events

26 RDN Collection Systems (Surfside, French Creek, Barclay Crescent, Pacific Shores, Fairwinds) I&I issues partially investigated Not much flow monitoring No or little I&I specific CCTV inspection performed However, vapour (smoke) testing has been done in most areas; the Morningstar area of French Creek being the notable exception Some storm cross connections have been fixed, as have minor leaks in manhole structure

27 City of Nanaimo Extensive flow monitoring, quality of data is improving CCTV cameras purchased and inspection programs planned (15km per year) Remediation being implemented $450k of relining work (650m) planned for 2010 Some manhole remediation completed Investigating / remediating known high flow areas

28 District of Lantzville New sewers should minimize I&I flow from a systems operations perspective Assuming that only permitted connections using new laterals are made to new sewers, I&I from private properties should be minimal RDN will monitor flows in the future

29 Town of Qualicum Beach Smoke testing is performed in the fall to identify inflow sources Manhole lids have been bolted Manhole barrels are now being power grouted (equipment purchased) 1.8km of CCTV inspection completed this year. Services with suspected I&I problems are being located No relining has been performed (pipes > 33 years old). Cross connections have been found and disconnected

30 City of Parksville A flow meter and weather station has been installed to report on I&I flows. Based on a 5 year return period, current I&I is estimated at 11,300 l/ha/d (Metro Vancouver allows 11,200 l/ha/d) Manhole lids have been bolted Leaking manholes are being injected with epoxy $90k of CCTV inspection completed on critical sewers last year which didn t indicate any significant problems Smoke testing has been completed in two of the City s older catchments The Foreshore area that is subject to tidal influence and high groundwater is known to have I&I problems Rathtrevor Park, the responsibility of BC Parks, is believed to have stormwater sewers that connect into Parksville s collection system

31 Example of flows observed during a 1 in 100 year storm event, December 2007 Pollution Control Centre ADWF (m 3 ) Dec 3 rd Flow (m 3 ) Flow ratio Greater Nanaimo (GNPCC) French Creek (FCPCC) , Nanoose (NPCC) 257 NA* NA Duke Point (DPPCC) ** 17.0 *NPCC is a small plant permitted to accept 2270 m 3 /d **DPPCC is a small plant permitted to accept 910m 3 /d

32 Reducing Sanitary Sewer Flows in the RDN

33 Collaboration is essential There are many sources of wastewater, therefore many solutions are needed, by many people Much has already been done Flow monitoring Investigation Remediation Sustainable development practices Community education and outreach RDN wastewater operatives see that flows are reducing What else can be done?

34 Understand Issues to find cost effective solutions Identify flow related issues and calculate the cost to accommodate the issue pollution spills, infrastructure upgrades - would it be cheaper to mitigate the source?

35 An example of an issue Environmental Spill Is it cheaper to: Add storage Increasing pumping capacity Increase treatment capacity OR Reduce I&I?

36 What can we do Improve overflow monitoring how much sewage spills during a given storm event, how acceptable is that to the community? Municipal workshops Define RDN objectives and agree common goals Set targets and how their attainment will be measured Compare I&I reduction programs/completed work Compare wastewater (water use) education/outreach programs Find out what is working and what is not Identify additional resources that can contribute to flow reduction (e.g. BC Parks, Ministry of Transportation) Agree action plans, with timelines, to reduce sewage flows

37 Funding opportunities to reduce sanitary sewer flows

38 Funding recently offered Federation of Canadian Municipalities The Green Municipal Fund Waterways Projects Ministry of Community & Rural Development Infrastructure Planning Grant Program BC s Community Water Improvement Program Building Canada Fund Canada/BC Infrastructure Program Canada/BC Municipal Rural Infrastructure Fund

39 Discussion