ADMINISTRATIVE REPORT Date: July 11, 1995 Dept. File No.4755-3 TO: Vancouver City Council FROM: General Manager of Engineering Services SUBJECT: Fraserview and Still Creek Sewer Inflow and Infiltration Reduction Programs. RECOMMENDATION A. THAT Council authorize City staff to continue to monitor the Fraserview sanitary sewer system and report back on the need for resumption of an inflow and infiltration reduction program if necessary. B. THAT Council authorize the Mayor to write to Burnaby Council advising them of Vancouver's Still Creek cleanup program and supporting continued Burnaby efforts to cleanup Still Creek's headwaters in the Metrotown area. COUNCIL POLICY Council has previously approved a number of recommendations concerning the reduction of pollution levels in the Fraser River, English Bay, and Burrard Inlet water bodies. PURPOSE This report provides Council with an overview of the results of the Fraserview Inflow and Infiltration (I&I) Reduction Program. It also requests Council authorization for continued monitoring of the Fraserview sanitary sewer system with staff to report back on the need for resumption of an I&I program if necessary. This report also provides an update as to progress of the Still Creek I&I Reduction Program. BACKGROUND In August 1992, Council authorized a $300,000 sewer system I&I reduction program for the Fraserview area. The objectives of this eighteen month program were to reduce sanitary sewage overflows to the Fraser River from the Elliot Street outfall and to eliminate sanitary sewage contamination of Vivian Creek. A May 1994 Council report provided an update as to the progress of this program. The 1994-96 Sewers Capital Plan included a three year, $600,000 I&I reduction program for the Still Creek area based on the model successfully used for the Fraserview area. This approach was approved by Council in the May 1994 report. As this program obviated the immediate need for sewer upgrading to service the Collingwood Village Development, VLC Properties contributed $455,000 towards its costs. The objectives of the Still Creek I&I Program are to eliminate sanitary sewage contamination of Still Creek, to increase the available capacity in the sanitary trunk sewer to prevent future flooding, to reduce the likelihood and scale of any possible future trunk sewer upgrades needed for new developments in the area, and to provide some reduction in combined sewer overflows at the Clark Drive sewer outfall. DISCUSSION Fraserview Program 2 Inflow and infiltration are terms used to describe stormwater which improperly drains into a sanitary sewer system. Stormwater can enter the sanitary system through leaky manholes, lids, and pipe joints in addition to incorrectly connected roof drains, drain tile, and catch basins. I&I flows can sometimes exceed the capacity of the sanitary sewer system causing backups into homes or overflows to the environment. Measures to reduce I&I flows in Fraserview have included: Identifying and correcting connections for fourteen homes found to be draining sanitary sewage to storm sewers which drain to Vivian Creek. Eight of these residences were also found to have storm connections to the sanitary sewer (reversed connections). Identifying and repairing thirty-nine homes with storm connections to the sanitary sewer. Installing lid sealing gaskets in sanitary manholes found to be intercepting significant amounts of street runoff. The last of this work was completed in the fall of 1994. Subsequent monitoring of storm sewers which discharge to Vivian Creek has confirmed the elimination of any sanitary sewage contamination. In addition to these repairs, a short, undersized section of the sanitary trunk sewer was upgraded. Final flow monitoring of the sanitary sewer system was conducted in the spring of this year. During the ten week monitoring period, thirteen significant rainfall events occurred. Prior to undertaking this program, an estimated eleven of these events would have resulted in sanitary sewage overflows at the Elliot Street outfall. This spring, however, no such incidents occurred. Based on these results, the Fraserview I&I Program has exceeded our expectations. While a storm of considerable magnitude might still cause an overflow, the data would suggest that these occurrences have been virtually eliminated. However, ongoing redevelopment of the Fraserview area will increase sanitary sewage flows requiring continued efforts to curtail I&I. One of the remaining significant sources of I&I flows is leaking old sanitary service connections. Fortunately, these pipes are replaced with new, more water-tight services upon property redevelopment. Currently, about 2% of the older homes in Fraserview are replaced annually. While extension of the I&I program would result in further reduction benefits, staff are not recommending it at this time. We anticipate that I&I reductions gained through the redevelopment process will more than offset the increased flows resulting from new developments. We therefore recommend that we continue to monitor the Fraserview system and report back on the need for resumption of an I&I program if necessary. Still Creek Program Like Fraserview, the Still Creek area has a sanitary sewer system with excessive I&I flows. The GVRD's Collingwood Sanitary Trunk sewer, which drains Vancouver's Still Creek and Burnaby's Metrotown areas, is surcharging during wet weather. In addition, sanitary sewage contamination has been found in Still Creek. Experience gained in locating and correcting reversed connections in Fraserview is being applied successfully to the Still Creek area. The first stage of this program has focussed on eliminating sources of 3 sanitary sewage contamination in the creek. To date, these efforts have located and corrected the following numbers of properties found with improper connections. Thirty-two properties with storm connections to the sanitary sewer system. Twenty-four of these same properties found to have sanitary sewage draining to storm sewers which discharge to Still Creek. A further eight properties have been identified with reversed connections and corrections to these are currently in progress. The Still Creek drainage area, with 11,000 properties, is approximately five times the size of the Fraserview area and is also much older. Approximately 30% of the area has been checked and cleared of faulty sewer connections to date. The relatively large number of properties identified with plumbing system problems can be attributed to the fact that in some areas the private property sewage systems predate the City's sewer system. Many properties were originally built with septic tanks. When City sewer services became available years later, a few homes tied one or both of their sewer systems to the wrong pipe. Future activities for the City's Still Creek program will include continued locating and correcting of properties with reversed connections, fecal coliform testing of the Still Creek storm sewer system, and video inspection of the sanitary sewer system to locate leaks. The GVRD will also be flow monitoring their sanitary trunk sewer to identify the extent of surcharging. This work will assist us in tracking the success of our I&I reduction efforts. The GVRD also plans to assess the condition of their sewer through video inspection in the fall. City staff are also cooperating with Burnaby on addressing Still Creek's I&I problems. Through this process, Burnaby has recently determined that they have I&I problems in their sanitary sewer system upstream of Vancouver in their Metrotown area. Burnaby system problems include wet weather sanitary sewer overflows to Still Creek just upstream of where it enters Vancouver and improper stormwater connections to the sanitary sewer. City staff recommend that to promote continued consultation at all levels, the Mayor write to Burnaby Council advising them of Vancouver's program and supporting continued Burnaby efforts to cleanup Still Creek's headwaters in the Metrotown area. Based on the results obtained to date, sanitary sewage contamination of Still Creek from Vancouver sources should be eliminated by the program conclusion. In addition, the level of surcharging occurring in the Collingwood Sanitary trunk sewer during wet weather should be significantly reduced and, subsequently, the danger of flooding abated. Some reduction in combined sewer overflows at Clark Drive should also result. Within two or three years, a decision is expected under the regional Liquid Waste Management Plan framework regarding any capital improvements necessitated by I&I flows. City staff expect that the results of our I&I reduction program will greatly reduce the scale of improvements which may be needed in the Vancouver Sewerage Area. * * * * * 4 ________________________________________________________________ City Manager____________________ Report dated: July 10, 1995 Date____________________________ Author: A. Grill Phone 7453 IRTS Number___________________ This report has been prepared in consultation with the departments Concurring Departments listed to the right, and they ______________________________ concur with its contents. ______________________________ Department Head_________________ ______________________________ Date____________________________ ______________________________ _________________________________________________________________ AJG/ajg Attach.