The Corporation of Delta COUNCIL REPORT Regular Meeting. South Delta Sanitary Sewer Capacity

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1 The Corporation of Delta COUNCIL REPORT Regular Meeting F.02 To: Mayor and Council File No.: /SD From: Engineering Department Date: July 6, 2012 South Delta Sanitary Sewer Capacity The following report has been reviewed and endorsed by the Chief Administrative Officer. RECOMMENDATION: THAT copies of this report be provided to Tsawwassen First Nation and the Greater Vancouver Sewerage & Drainage District. PURPOSE:. The intent of this report is to advise Council of municipal sewer capacity for South Delta. BACKGROUND: The community of Delta has been proactively planning its development and growth based on the 1986 Official Community Plan, as amended. This plan has allowed for moderate growth in Tsawwassen and Ladner, assuming both infill development and some new developments. In light of the recent discussions with Tsawwassen First Nation regarding the provision of sanitary sewer servicing, staff have undertaken a capacity analysis of Delta's existing sanitary sewer forcemain system. This report provides the estimated peak flows based on the current Official Community Plan and capacity of the existing sanitary forcemain system serving Tsawwassen, Ladner and the Tilbury industrial areas. DISCUSSION: The population in the communities of Ladner and Tsawwassen has remained relatively stable over the past decade. In the 2001 census, the population in Ladner was 21,367, and 21,084 in Tsawwassen. The most recent census data, 2011, indicates a population of 22,204 in Ladner and 21,181 in Tsawwassen. The population data for current and estimated future build out for the Ladner and Tsawwassen areas are summarized as follows based on the population growth projection of the Metro Vancouver 2040 Regional Strategy:

2 South Delta Sanitary Sewer Capacity /SD Page 2 of 3 July 6,2012 Corporation 2011 Area Ladner 22,204 Tsawwassen 21,181 North Delta not shown ,165 23, Population Increase 2011 to ,247 25,895 3,691 24,127 24,315 3,134 Sanitary Sewer System Capacity The sewage from Tsawwassen and Ladner is pumped through a series of forcemains and pump stations to the Annacis Island Sewage Treatment Plant (Attachment A). The trunk forcemain system is approximately 20 km in length and terminates at the South Surrey Interceptor. The majority of the sewage flow in Tsawwassen is pumped by the Gillespie. Pump Station, and then depending on the flow condition, boosted by the Ladner Trunk Pump Station. The sewage flows in Ladner are primarily pumped by the Manor North Pump Station, and then boosted during higher flow periods by the Ladner Trunk Pump Station. Marina Gardens development, which has,a separate pump station, discharges into the trunk forcemain downstream of the Ladner Trunk Pump Station, at 60 Avenue. That system has been designed to accommodate the anticipated growth of build out. Due to-several breaks and sewage leaks that have occurred over a number of years, the sewage system between Tsawwassen and Ladner has been provided with parallel forcemains. They provide some level of redundancy so that in the event of a failure, the system will function at a reduced capacity for an interim period. The implications of a forcemain break affecting populations the size of Ladner and Tsawwassen are significant. Further system improvements, particularly north of the Ladner Trunk Pump Station, are planned to improve the long-term system reliability should there be a forcemain break or maintenance requirement in the future. Several recent upgrades have been under taken, namely the twining of approximately 5 km of forcemain from Ladner Trunk Pump Station to 72 Street. The 2012 sewer system analysis concluded the existing peak sewer flows from South Delta and Tilbury industrial areas to the Greater Vancouver Sewerage & Drainage District's Annacis Island Waste Water Treatment Plant are 1,050 liters per second. The break-down of the respective contributors is summarized in Omni Engineering's report, included as Attachment B. The current Official Community Plan flow is estimated at 1,150 liters per second based on Delta's design criteria. The peak capacity of the existing system has been estimated at approximately 1,200 liters per second.

3 South Delta Sanitary Sewer Capacity /SD CONCLUSION: Page 3 of 3 July 6,2012 In summary, Delta's Official Community Plan predicts some population increases in the communities of Ladner and Tsawwassen. These changes would likely have limited impact on the existing sewage infrastructure, and therefore the existing sewage infrastructure appears to be able to accommodate Delta's needs as projected in the Official Community Plan. A modest reserve capacity of approximately 50 liters per second appears to be available, however, should not be fully considered as spare capacity. The analysis clearly indicates that there is no reserve capacity available for Tsawwassen First Nation's long term sewage needs. Steven Lan, P.Eng. Director of Engineering Department submission prepared by: John Lee, Utilities Engineer & Harald Fograscher, Manager of Utilities jhl/sdr ATTAC.HMENTS: A. System Configuration B. System Flows - Consultant's Memorandum

4 SYSTEM CONFIGURATION TILBURY PUMP STATION ANNACIS ISLAND WASTEWATER TREATMENT PLANT 'c,.. -.:"- ~ MANOR NORTH PUMP STATION 60TH AVE CONNECTION, w., 'H~"";' j j i!=-==.. ~./ LEGEM:;:',',;.'C"'~'W '0 "... '''(MF ~ -'-!J~~, GILLESPIE PUMP STATION... 'c,... ~,~ "_C'''-'~C<'~~!,-'::'''''''~-'=''''''~ e;>=~ "'~_"' h "'1 "';"C:~"'''J~ -,:;o,~<",~,~ '"""",,,;. <>_~...,,~ DELTA SI\NITARV FORCE MAINS AND PUMF STATIONS»-j ii "'0(') Dl:::r: com COs:... 2 o -j ::>

5 Omni Engineering Inc. Delta Forcemains # fWelch Street North Vancouver, B. C. V7P 1 B7 Fax: Phone: Date: July 9,2012 ATTACHMENT B Page 1 of 4 TO: Corporation of Delta ATTENTION: Hugh Fraser FROM: Peter Mickelson 1. INTRODUCTION This memorandum reviews the approximate peak loading and capacity of the primary sanitary sewer pumping and forcemain systems serving Tsawwassen, Ladner, the Tilbury industrial site and other downstream areas. Peak loadings for 2012 and for the future build out development of the Corporations OCP are estimated for comparison to the system capacity. As noted in previous reports the Corporation's regional pumping and forcemain system has little storage capacity. As a consequence major system components are required to handle peak inflows. The peak capacity of the existing system has been estimated using computer models while the peak loading has been based on previous values as well as selected operational flow data supplied by the Corporation. Previous computer models have been upgraded to reflect known system changes including all forcemain twinning's downstream of the Ladner Trunk pump station to nnd Street. Key system-pumping components include the: BC Ferries Pump Station(s); Gillespie Pump Station; Manor North Pump Station; Ladner Trunk Pump Station; City of Vancouver's Leachate Pump Station; Tilbury Pump Station;,. Flow monitoring station at the downstream end of the forcemain, Key system forcemains include those which connect the key pump stations and extend to the South Surrey Interceptor at the downstream end, Smaller local lift stations, forcemains and gravity collectors provide the local inflows to the key facilities and components noted but are not considered herein. 2, Estimated 2012 Peak Wet Weather Flow Ii OCP Build out The inflow loadings used in this review are based on peak wet weather flows developed in 1990 and updated in 2010 and appear to reasonably represent recorded flows. Estimated future increases to calculate OCP build outs are shown below, Page 1014

6 Omni Engineering Inc. Delta Forcemains ATTACHMENT B Page 2 of Population Data Population data for current and estimated build out populations for the Ladner and Tsawwassen areas have been provided by the Corporation of Delta as foilows:. Table Population Data Corporation Population Area* Increase 2011 to 2041 Ladner 22,204 24,165 25,247 25,895 3,691 Tsawwassen 21,181 23,812 24,127 24,315 3,134 'North Delta not shown Delta design criteria have been used to estimate the additional demand on system capacity required by the population increase. 2.2 Population Distribution Table Population Distribution Density Parameters Category Value Unit Persons per hectare Single Family Residential (SF) 66 (ha) Multi Family Residential Persons per hecta re (MFL (ha) % of Land Area Assigned to SF 40% Percent of total % of Land Area Assigned to MF 60% Percent of total 2.3 Additional OCP Sanitary Flows Using Delta sanitary design criteria and the assumed density the following additional peak sanitary flows are estimated: Table Additional Sanitary Flow Estimate Peak Municipality SF Area MF Area adwf Factor 18:1 PWWF Area (ha) (ha) (L/day/cap) (Llha/day) (L/s) 33.8 Ladner ,200 (use 34) 28.7 (use 29) Tsawwassen ,200 Total Use 63 Page 2 014

7 Omni Engineering Inc. Delta Forcemains ATTACHMENT B Page 3 of Required OCP Capacity Table Estimated 2012 Peak Flow & Calculated OCP Build out Flow AREA Flows (lis) Comments 2012 OCP Build Increase I PWWF Out Tsawwassen Gillespie Lowlands Tsawwassen Gravity Bypass or Gillespie Highlands Imperial Gravity Bypass or Gillespie Village TGCC (Phase Gravity Bypass or Gillespie 8: 2) BC Ferries BCF 300 forcemain Total Tsawwassen Holly Park Manor North Total Ladner Total to Ladner Pumped at Ladner Trunk Trunk P Stn PS City of Vancouver 60 m Avenue Marina Garden Development' Tilbury Allowance' River Road Allowance' input Total to GVS8:DD.. Manna Gardens, TIlbury IndustnaL area and RIver Road are allowances In addition to OCP estimates TabLe 2.4 estimated the 2012 peak flow demand at 1050 LIs. Adding the combined additional 63 lis (TabLe 2.3) for the Ladner and Tsawwassen areas plus allowances for Marina Gardens (15 LIs), Tilbury (20 LIs) and River Road (2 l/s)increases the estimated OCP demand to 1150 lis. The total system capacity has been estimated at 1200 LIs (shown below) which indicate some 50 lis of capacity remaining in the DeLta sanitary forcemain system. Upstream Ladner Truck Downstream Total Capacity Comment Capacity (l/sec) Capacity (ll sec) Capacity (L/sec) (L/sec) Approximate Only In view of the assumptions made in estimating system capacity it is considered that the DeLta sanitary forcemain system does not have adequate capacity to support flows greater than the current estimated OCP demand level. Page 3 of4

8 Omni Engineering Inc. Delta Forcemains ATTACHMENT B Page 4 of PRELIMINARY FINDINGS 3.1 Findings Analysis of the system indicates that: 1. The 2012 peak flow demand in the Delta sewer forcemain system is estimated to be 1050 lis based on current flow records. 2. The peak flow is estimate to increase to 1150 lis in 2041 and is considered the demand at build out under the current OCP with increased flow coming primarily from the Ladner and Tsawwassen areas. 3. The pumping and forcemain capacity of the Delta forcemain system is estimated to be 1200 lis. 4. The capacity of the system is considered able to meet current OCP requirements but with no spare capacity (1200 lis capacity less 1150 lis OCP = 50 lis excess). In view of the assumptions made in the analysis the excess 50 lis should not be considered as spare capacity. 5. Additional flow demands in excess of OCP would require system modifications to increase force main and pumping capacity. Page 4 of4