ADMINISTRATIVE REPORT

Date: November 28, 1997

Author/Local: SMcTaggart/7356

CC File No. 5809

TO:	Vancouver City Council
FROM:	General Manager of Engineering Services
SUBJECT:	Storm Flooding Update and Proposed Assistance Program

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RECOMMENDATION

A.THAT the General Manager of Community Services and the General Manager of Engineering Services review and report back to Council on the expansion of private property impermeability controls to further address aesthetic and infrastructure issues.

B.THAT one Sewer Operations position and one Plumbing Inspector position, subject to position evaluation by Human Resource Services, be added for a one year term at an estimated cost of $130,000 with funding from the 1997 surpluses in the Sewer Connection Permits Account .

C.THAT approval be given for the lease of a vehicle, supplies, equipment and operating expenses for a one year period at a cost of $20,000 with funding from the 1997 surpluses in the Sewer Connection Permits Account.

D.THAT $40,000 be approved from Contingency Reserve, with an ongoing annual cost of $15,000, to establish office space at 456 West Broadway to relocate sewer and plumbing staff involved in the sewer separation, connection inspection and flood assistance programs.

E.THAT $50,000 be reallocated from the special structure inspection program to the precautionary rodding program, in the Sewer Maintenance account of the 1998 Operating Budget, to allow for additional sewer connection rodding.

MANAGER'S COMMENTS

The General Manager of Engineering Services RECOMMENDS approval of A through E, noting that the additional positions are term for a period of one year. The additional cost to the 1997 budget is $40,000 (Contingency Reserve) and to the 1998 and subsequent budgets, $15,000. The remainder of the costs are covered by reallocation from existing budgets.

COUNCIL POLICY

In the early 1970's, Council approved the policy of separating sanitary and storm sewers, starting in the West End and Downtown areas. This policy was reaffirmed in 1981 as part of the Sewers Long Range Capital Plan, along with the adoption of the 1% life-cycle sewer replacement policy. Both of these policies were reaffirmed in the 1991 Policy Report on standards for sewer collection infrastructure.

In 1991, Council approved the following basic objectives for the sewer collection infrastructure:

a)to safeguard public health and minimize impact on the environment by collecting domestic, commercial and industrial liquid wastes for disposal;

b)to minimize property damage, public nuisance, and impact on the environment by collecting and controlling precipitation runoff for disposal;

c)to maintain and rebuild these facilities in a timely manner, so that their operating efficiency is maintained, service levels are maintained and the City’s interests are protected;

d)to work towards the elimination of all raw sewage overflows into the environment over the long term in the most cost-effective way;

e)in addition to other sewer infrastructure design standards, Council approved the current standard of constructing all new sewers in residential areas for a 5-year return storm.

In February 1995, Council approved the Green Barrel and Roof Leader Disconnection Pilot Programs to assist in water conservation, flooding risk reductions and combined sewer overflow (CSO) reductions.

In October 1995, Council approved new RS-5/RS-6 design guidelines governing private property site coverage and impermeability to provide aesthetic benefits and to help reduce stormwater runoff into the sewer system. This in turn assists in reducing flooding risks as well as providing CSO reduction benefits.

As part of the Budget Management Program, Council established a policy in 1992 that any recommendations for increased staff or enhanced programs be accompanied by recommendations for matching cost decreases or related revenue increases.

PURPOSE

The purpose of this report is to update Council on recent storm related basement flooding, to outline the efforts and initiatives underway to reduce the risk of future flooding, to recommend a temporary City service to assist citizens who wish to take their own measures to guard against basement flooding, to request funds to establish an office at 456 West Broadway, and to recommend an increase in the level of service for the sewer connection precautionary rodding program.

BACKGROUND

Vancouver periodically experiences major storms where the runoff exceeds the capacity of the City’s sewer system. This can result in sewage and stormwater backing up into residences through household sanitary fixtures (eg. toilets, bathtubs and sinks). Figure 1 shows the number of major floods each year in Vancouver since 1979.

Following the storms which occurred in 1994, Council received a report and adopted a number of recommendations. A status update of these recommendations is included in this report and in the attached appendices. Since the 1994 report, the frequency of storm events in Vancouver has increased even more.

Prior to 1996, the number of storms varied between zero and three in any given year, with the overall average being less than one event per year. In 1996, however, seven major storms occurred which caused flooding. This year, we have already had five major floods to date. Environment Canada has reported that over the past few decades there was a substantial increase in high intensity storms in the Vancouver area. Figure A in Appendix A illustrates this increase.

Council also adopted a new policy in 1986 restricting building heights in RS-1 areas to preserve views and building bulk. This required the construction of deeper basements for developers wishing to obtain the maximum floor space ratio. Consequently, the basement fixtures that flow by gravity to the City’s sewer main generally need deeper public sewer connections which can result in greater flooding potential during very intense rainfalls. Figure 2 shows the number of buildings that have flooded since 1979 as a result of City system surcharges during major storms.

The Acting Director of Risk & Emergency Management advises that, where the sewer system is functioning as designed, according to the standards in place at the time of construction, the City is not liable for flooding claims. In some cases, however, the situation may have been compounded by other problems such as the presence of tree roots in the City sewer system or in private connections which reduce flow capacity. In such cases, depending upon the circumstances, the City may be responsible. Each claim is investigated fully on an individual basis, and payment made where warranted.

DISCUSSION

To reduce the risk of basement flooding resulting from sewer backups, a number of initiatives have been developed and are being used. These initiatives are listed and described in Appendix B. This report recommends that three of the initiatives be reviewed or increased in level of service. These initiatives include site impermeability controls, the flood assistance program, and the precautionary rodding program.

Impermeability Control

By controlling the impermeable area on new developments, the rainfall runoff entering the sewer system can be affected. Council recently approved new RS-5 and RS-6 zoning for City neighbourhoods requiring the amount of impermeable materials, including building coverage, to be 60 percent or less of the total site area. By decreasing impermeable areas, more rainfall runoff can seep into the ground naturally instead of discharging directly to the sewer system. Also, limiting impermeable areas provides aesthetic benefits as more "green space" is retained. It is recommended that the General Managers of Community Services and Engineering Services report back to Council on extending impermeability controls to other areas of the City.

Flood Assistance Program

As a result of the large number of floods that the City experienced over the past two years, Engineering Services has recently started to provide, on a limited basis, advice to homeowners wishing to implement flood protection measures on their own properties. These measures include pumping systems, site grading and backflow preventors.

Many individuals and families who have experienced sewage backups have indicated the great inconvenience and mental stress they have gone through. Some degree of mental stress also remains with them just knowing that another major storm could flood their homes again. In addition, insurance companies will typically increase premiums and deductibles for sewerbackup coverage should the homeowner have multiple flooding claims. Furthermore, if it appears that flooding could occur repeatedly, insurance companies will generally cancel their sewer backup coverage altogether.

While the City is responsible for many of the initiatives to reduce flooding potential, homeowners can take their own measures to provide greater flood protection for themselves. One of the most effective measures is to install pumping systems. With a properly installed and operating pump in place, backups from the City system can be prevented. These systems, however, are often quite costly to retrofit into existing homes.

Some citizens have requested that they be allowed to install simple backflow prevention devices. Conventional backflow valves are prone to clogging by solids if used on sanitary lines. As a result, they have only been used on stormwater systems in the past. However, a new backflow prevention device has recently been developed which is much less prone to failure on sanitary or combined systems. Several hundred of these devices have been installed in homes in Edmonton over the past year and have worked well in minimizing basement flooding from their combined systems.

The Permits & Licences Department are now allowing these new backflow preventors to be installed on sanitary and combined lines where flooding is a concern. This provides homeowners with a less costly method of dealing with backups from the City system. It should be noted that these devices are not as effective as pumped systems because the household plumbing generally cannot be used during a major storm event. The duration of backups, however, is relatively short thus minimizing the inconvenience of not being able to use their plumbing fixtures. This makes the backflow prevention option a much more cost-effective method, if installed and maintained correctly, to prevent sewage and stormwater from backing up into homes.

By installing these devices in homes that have been flooded, the mental stress to homeowners regarding future flooding would diminish considerably. In light of the recent increase in storm events, and with this new low cost backflow prevention option available, Engineering Services is proposing to contact all homeowners who have experienced flooding in the past ten years to inform them of this new option.

Installing these new backflow devices properly and cost-effectively does involve specialized technical expertise as well as City inspections. There can be a network of pipes connecting different areas of a house to the sewer system, making their installation very complex. Because of this, and because it is a new plumbing procedure for Vancouver which requires retrofitting existing homes, it is recommended that a specialized City crew be hired for a one year period to provide the necessary expertise to contractors and to assist homeowners in determining which system best meets their needs. Edmonton has a financial subsidy programto assist homeowners with similar problems, however, we do not recommend this in our case. We feel it is better to provide support through a special staff team who can offer the homeowners with valuable on-site guidance and advice. This would also create additional public goodwill.

With this program in place, there would initially be a large plumbing inspection workload which current staff could not handle. The special one year team would be able to provide the necessary inspections for these installations. This would also allow us to waive the regular plumbing permit fees for the homeowners who have experienced flooding. To carry our this program, we recommend that $130,000 be allocated to fund the team made up of one Sewer Operations position and one Plumbing Inspector position along with $20,000 for a vehicle and equipment.

The City’s existing sewer separation and inspection teams are located in City Hall’s East Wing. Their current office area is limited and can not be expanded at the existing location. This space has also become too small for their current operation. Furthermore, with the addition of the new flood assistance team, new office space would be required. It is therefore recommended that alternate space be arranged at 456 West Broadway and that the current teams be relocated there. Upgrading the office space, including furnishings and equipment, would need to be done at an estimated cost of $40,000. In addition, there would be an ongoing cost of $15,000 annually.

Precautionary Rodding Program

The City also carries out a precautionary rodding program for connections and main sewers to reduce the occurrence of blockages and backups. This program is a preventative maintenance program designed to reduce the potential for system backups before problems occur. Homes are often flooded because main line sewers or sewer connections become restricted or blocked by root intrusion from private or City boulevard trees. In 1996, approximately 1,000 connections became blocked causing backups, with 800 of these resulting from City tree roots.

Due to budgetary constraints, only a limited number of private property connections can benefit from the precautionary rodding program. In past years, the recommended service levels for sewer maintenance decreased as a result of budget cutbacks. Currently, this program allows for about 120 precautionary roddings to be done each year. Because of the recent increase in storm frequency and the greater number of homes that have been flooded, the General Manager of Engineering Services recommends that $50,000 be reallocated within the 1998 Operating Budget, Sewer Maintenance account. We estimate that thisincrease would allow about another 300 precautionary roddings to be done each year. This would result in a reduction of backups from blocked connections. More importantly, this service creates public goodwill for citizens who have experienced multiple sewer backups caused by City tree roots.

SOCIAL IMPLICATIONS

The goal of the one year flood assistance program is to provide a service to Vancouver citizens who have experienced sewage and stormwater flooding from the City’s system. The program would help them determine cost-effective options to reduce the risk of future flooding. It would also provide the necessary installation inspections that are required. This service will enable citizens to further reduce their mental stress related to flooding and create general goodwill. Furthermore, it is expected that insurance companies would maintain sewer backup coverage if homeowners install pumps or backflow devices.

By increasing the level of service for the precautionary rodding program, additional connection rodding could be done which would result in a decrease in backups. The increased level of service would result in a significant benefit to many citizens who experience regular sewer backups.

FINANCIAL IMPLICATIONS

The cost of the Sewer Operations position and the Plumbing Inspector position for a one year period is estimated to be $130,000, including fringe benefits. In order for them to carry out the program, a vehicle, supplies, equipment, and operating expenses, at an estimated cost of $20,000, will be needed. Sufficient funds to cover these costs are available from the 1997 surpluses in the sewer permit connection account. In 1996, the City installed approximately $6,000,000 worth of public sewer connections through our permit process. The installation costs are recovered from fees required when new buildings are constructed or significant renovations are undertaken. These costs can vary from year to year depending on the lengths, depths, locations and soil conditions of each connection installation. Over the past year, we have also implemented new field installation procedures which have resulted in construction cost efficiencies. In 1997, we estimate that there will be a net surplus to cover the one year program.

The cost to relocate the sewer separation and inspection teams from City Hall to 456 West Broadway and to establish office facilities for the flood assistance team is estimated to be $40,000, with an ongoing annual cost of $15,000. This would be funded from the 1998 Operating Budget.

Due to recent efficiencies achieved in the sewers special structure inspection program, $50,000 can be reallocated to the precautionary rodding program in the Sewer Maintenance account of the 1998 Operating Budget to increase the level of service for connection rodding.

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APPENDIX A

RAINFALL TRENDS IN VANCOUVER

Environment Canada has reported that there has been a substantial increase in high intensity storms in the Vancouver area over the last two decades. Figure A shows the number of days when the intensity of the rainfall at Vancouver International Airport exceeded 10 millimetres per hour using a 5 year running mean. This figure clearly shows an increasing rainfall trend. It is interesting to note that Environment Canada also reports that rainfall measurements taken in Victoria, Comox and Abbotsford do not show similar increasing trends which suggests that the recent changes in rainfall patterns in Vancouver are caused by localize factors. It has been suggested that increasing urbanization and development may be playing a role in this rainfall change.

INITIATIVES TO REDUCE FLOODING IN VANCOUVER

To reduce the risk of basement flooding resulting from City sewer main backups, a number of initiatives have been developed and are being used. These include:

a)Local System Changes- Often, some cost-effective changes or pipe section upgrading can be made to provide increased capacity and additional stormwater conveyance in the sewer system. This involves making structural changes or advancing the reconstruction of parts of the system.

b)Infrastructure Reconstruction Program- This program rebuilds the City’s aging sewer infrastructure. Upgrading of older sewers generally occurs at the end of their useful lives which is usually 80 to 100 years. The City’s reconstruction program provides for the replacement of about 1% of the system annually such that all sewers are rebuilt on a life-cycle basis. All sewers replaced are upgraded to today’s higher capacity standards. This program requires a budget of about $14 million annually. The replacement value of Vancouver’s entire sewer system is in excess of a billion dollars. Because of the high cost of reconstructing sewers, it would be impractical to upgrade all of the older parts of the system over the short term.

c)Sewer Separation- Vancouver’s older sewers were mainly built as "combined" systems. This means that only single pipes were constructed in the streets to carry both sanitary sewage and rainfall runoff mixed together. If the runoff from an intense storm exceeds the capacity of the main sewer, sewage can back up in sewer connections to private properties and flood homes through their sanitary fixtures. The sewer reconstruction program replaces old combined sewers with new twin pipes to keep the sanitary system separate from the storm system. With a completely twinned system in place, backups through sanitary fixtures due to high intensity storms should be eliminated.

d)Regulation of Sewer Connections- When applications are made for new sewer connections, connection depths, plumbing fixture levels, and in some areas, the need for flow discharge controls are reviewed. Appropriate restrictions are required to reduce the possibility of basement flooding. Because of the increased flooding occurrences over the past few years, the allowable depth of building fixtures has been raised in combined sewer areas to minimize backups.

e)Inflow and Infiltration Program- In separate sewer areas, the City has a program to reduce the amount of extraneous stormwater entering sanitary sewers. This program is currently underway in the Still Creek area and has been successful in rerouting stormwater into the Creek, thereby reducing flooding risks in immediate downstream areas.

f)Impermeability Controls- Council has recently approved new RS-5 and RS-6 zoning for City neighbourhoods to provide more control over the design of new homes. Along with other design guidelines, the new zoning contains a bylaw section to limit the amount of impermeable materials, including building coverage, to 60 percent of the total site area. This provides aesthetic benefits as more "greenspace" is retained and reduces the potential amount of runoff to the sewer system.

Although this new zoning may not be appropriate for all areas of the City, the impermeability controls could be extended to neighbourhoods currently zoned RS-1, RS-1S, RS-3, RS-3A, and possibly RS-2, RS-1A, and RA-1. This report recommends that the General Managers of Community Services and Engineering Services report back to Council on extending impermeability controls to other areas of the City.

g)Sump Exfiltration Pilot Program- A pilot program has been established to evaluate the effectiveness of decreasing storm runoff from properties through the use of exfiltrating sumps. These sumps have been designed to allow stormwater from building roof leaders and drains to flow naturally into the ground as much as possible before discharging to the City sewer system. If found to be successful, a recommendation will be made to make this requirement applicable to all new home construction.

h)"Green Barrel" Program- "Green Barrels" are used to store rainwater for garden usage thus conserving domestic water and reducing rainfall runoff from properties. To date, about 600 barrels have been purchased through this program.

I)Roof Leader Disconnection Pilot Project- A soil analysis has found that some areas of the City have enough permeability to allow disposal of roof leader runoff by infiltration into the ground. A volunteer roof leader disconnection pilot project was undertaken last fall in one area to assess the effectiveness of this type of program. Although our initial participation rates in the pilot program were disappointing, this does remain a viable option for reducing runoff in some parts of the City.

j)Flood Assistance Program- The City has also started to provide, on a very limited basis, some advice to homeowners wishing to implement flood protection measures on their properties. These measures include pumping systems, site grading and backflow preventors.

k)Precautionary Rodding Program- Through the Sewer Maintenance budget, we are able to carry out a precautionary rodding program which cleans out sewer pipes on a preventative maintenance basis to reduce the occurrence blockages and backups. Homes are often flooded because main line sewers or sewer connections become restricted or blocked by root intrusion from private or City boulevard trees.

l)Sewer Connection Relay Program- Through the Sewers Capital Budget, we are able to relay the most critical and problematic sewer connections. This reduces the flooding problems resulting from these connections. In 1996, we were able to relay approximately 100 connections through this program. Engineering Services is also currently trying new trenchless technology methods to replace sewer connections. If successful, the cost to replace problem connections will be reduced. This would allow us to replace more connections through our Capital Programs.

(c) 1997 City of Vancouver