Loading...
HomeMy WebLinkAboutWastewater Collection System Policy Discussion Commission Memorandum REPORT TO: Honorable Mayor and City Commission FROM: Rick Hixson, City Engineer Craig Woolard, Director of Public Works SUBJECT: Wastewater Collection System AGENDA ITEM TYPE: Discussion and Commission Guidance MEETING DATE: August 5, 2013 KEY ISSUES AND RECOMMENDATIONS: In 2007, the City of Bozeman adopted a Wastewater Facilities Plan that divided the City into defined wastewater drainage zones. The capacity of the collection network in each zone was designed to accept wastewater from the existing homes and business and accommodate the projected flow from new development. The Wastewater Facilities Plan outlined a collection system that minimized the use of wastewater pumping station. Three developers have recently approached the Department of Public Works with requests to build housing and apartments on the west edge of Bozeman in a drainage basin (or drainage zone) currently without sewer service. Although the technical details of each request differs, each developer is asking to transfer sewage from proposed developments into an existing wastewater drainage basin thereby utilizing some of the capacity allocated to current and future development in that basin. Resolution of these requests will have a significant impact on the development of Bozeman. This memorandum was prepared to aid a policy discussion about the current status and future development of the wastewater collection system to serve the western edge of Bozeman. The memorandum: Provides background information on the approved Wastewater Facilities Plan and the design philosophy used to prepare the plan. 118 Provides an overview of the requests received from the Norton, Valley West and Braxton developments and their implications for current and future development. Provides a summary of key policy issues that should be considered. Provides Staff recommendations for proposed developments and future infrastructure funding. The expansion of the Bozeman wastewater collection system to date has been driven by development. Bozeman’s topography has allowed this expansion largely by extending and over sizing gravity mains. These projects can be managed by individual developers and paid for using a combination of impact fees, payback and special improvement districts. Although these projects have at times been controversial, this approach to date has provided Bozeman with a wastewater collection system that is well designed and constructed with a minimum number of pumping stations. As Bozeman expands to the west (i.e., west of Cottonwood Road), providing sewer service will require the construction of a major system to pump wastewater to the Water Reclamation Facility (WRF). Design and construction of the lift station, force main and trunk sewer required to provide service is beyond the capabilities of individual developers. Without a complete system in place there is limited capacity for expansion of wastewater collection capacity on the western edge of Bozeman. The recent requests for sewer service have significant policy implications that must be considered before granting (or denying) these requests. As such, Staff recommends that the Commission: • Consider the implications of constructing additional wastewater collection capacity on the western edge of Bozeman. • Allow the development proposed at Norton, Valley West and Braxton to connect permanently to existing sewer capacity provided that (a) all facilities are constructed to City of Bozeman standards and (b) an update of the wastewater facilities plan be initiated immediately to mitigate the impacts of allowing the proposed developments to utilize existing collection capacity. Staff estimates the update will cost approximately $150,000. • Utilize revenue bonds to finance the construction of the major sewer infrastructure necessary to facilitate community growth on western edge of Bozeman Staff is requesting that the Commission review and discuss each recommendation. Staff will prepare the appropriate administrative policies and documents based on Commission guidance. BACKGROUND ON THE WASTEWATER FACILITIES PLAN: The City of Bozeman has been formally and methodically planning for its future infrastructure needs since 1958. Each updated plan has built upon previous efforts as well as incorporating new ideas and new technology. Whereas in 1958 it was possible to present the entire plan in one City Plan, today individual facility plans are prepared for each major element of infrastructure – water, wastewater, streets, solid waste and storm water. The most recent Wastewater Facility Plan was reviewed and adopted by the City Commission in 2007. 119 This most recent plan had two principal objectives. The first was to provide the groundwork for construction of a new Water Reclamation Facility (WRF). This planning led to the successful construction of what is now the most efficient and modern wastewater treatment plant in the state. The second major objective was to extend the design of the wastewater collection system into un-annexed areas to the west of the existing City limits. This planning effort was particularly important because in many places the City had reached the limits of its ability to provide gravity sewer service. In order for the city to expand into those areas, wastewater will have to be pumped back uphill and in some cases across I-90 to reach the WRF. In general, ground elevations in the valley decrease from south to north and from east to west. This topography has allowed Bozeman to develop a primarily gravity based wastewater collection system. However as a consequence of the valley’s natural topography, wastewater collected at locations west of the WRF and Cottonwood Road will have to be pumped back uphill for treatment. As shown in Figure 6-4 “Future Drainage Sub-basins” from the 2007 facility plan (attached to this memo) the topography results in long narrow drainage zones to collect wastewater by gravity. One of the guiding principles used to design these future drainage basins was to minimize the number of lift stations required. It is more difficult, costly and time consuming to maintain and operate many small lift stations than it is to operate a few regional lift stations. Even small lift stations require a substantial investment in design and construction. All lift stations provided for municipal use must also have a backup power supply (generator) and control systems. Lift stations are costly to operate and maintain and less reliable than gravity systems. Transferring wastewater from the lift station often requires use of a force main, a pipe filled with sewage operated under pressure. Force mains are typically more expensive than regular sewer pipe and in almost all cases require additional valves and controls relative to gravity sewers. For these reasons the 2007 Wastewater Facilities Plan minimized the number of lift stations and force mains required to extend the collection system to the west and recommended that only two large lift stations be constructed near the I-90. NORTON, VALLEY WEST AND BAXTER DEVELOPMENT PROPOSALS: Staff has been approached by three developers with projects located on annexed land on the western edge of Bozeman where the required wastewater collection infrastructure does not exist (see attached figure). The proposed Norton, Braxton and Valley West developments will require lift stations in order to convey wastewater to the WRF. One of these lift stations (the Norton Lift Station) already exists. Its construction and concern over proliferation of small lift stations serving individual subdivisions were one of the key considerations for updating the Wastewater Facility Plan in 2007. The Braxton and Valley West projects would require the construction of new lift stations which were not anticipated by the wastewater facility plan. Furthermore, none of the gravity trunk mains required to serve these proposed developments has been installed in the drainage zones to which they properly belong as specified by the Facilities Plan. Too conform with the Facilities Plan, all three developments would utilize the Baxter 120 Creek drainage zone. Representatives of each project have asked to temporarily pump their wastewater into the drainage zone immediately to their east (referred to as the Cattail Creek Zone in the wastewater facility plan) until such time as the infrastructure intended to serve Baxter Creek zone is installed. While capacity currently exists in Cattail Creek zone, it was not designed to accept wastewater from the zone to the west. If these developments are allowed to use a portion of this available capacity, some of the property currently designated to Cattail Creek zone would be unable to make use of the designated capacity unless the unaccounted for projects were disconnected and their flows removed. Staff has serious concerns about trying to craft an agreement that requires disconnection of functioning sewer at some specified future date. Staff does not recommend temporary sewer connections of any type. All three of the proposed projects are located in the Baxter Creek drainage zone which was designed with a regional lift station at its north end which is designed to pump wastewater through a force main, across the interstate to the WRF. The cost of the force main and lift station was estimated at $6 Million dollars in 2007. This zone was also designed with a large diameter gravity trunk main which was estimated to cost an additional $7 Million dollars. These are the capital improvements which need to be in place in order to serve the proposed properties as designed in the 2007 wastewater facility plan. POLICY ISSUES: Allowing reallocation of the capacity available in an adjacent (i.e., Cattail Creek) drainage zone has a number of significant policy implications. These include: 1. Adding properties to a drainage zones other than zone designated in the adopted Wastewater Facilities Plan requires the exclusion of properties elsewhere in the zone. 2. Removing properties from a drainage basin reduces the number of properties available to pay for the required trunk mains and lift stations in the future. 3. Temporary sewer connections of any type present significant financial, administrative and public health challenges. 4. Given the location of the subject properties it may be many years, if not decades, before sufficient property is annexed into this zone to pay for the required trunk lines, lift station and force main. 5. Granting this exception to the adopted Facilities Plan may set a precedent that will result in a poorly planned wastewater collection system. 6. Other parties have considered buying these properties but have decided not to purchase based in part on information contained in the facility plan and on staff recommendations. 7. Not conforming to the adopted facility plan may create a conflict in the future if a project within the proper zone wants to develop but the capacity no longer exists. 8. This practice has the effect of devaluing the property in the proper zone to the benefit of the adjacent, more distant zone. 9. Staff does not believe that individuals within a subdivision that is already served by sewer could be included in a Special Improvement District (SID). 10. The drainage zone boundaries were created and adopted through a public process – one that was reviewed and approved by both the city commission and the Montana Department of Environmental Quality. 121 11. The properties that the Norton proposal would replace were specifically called out in the conditions of approval for Baxter Meadows. One of those properties has changed ownership after the buyer confirmed with the City that there was sewer capacity. 12. The impact on the Meadow Creek Payback District. In 2006 the Meadow Creek subdivision installed its offsite infrastructure which included several miles of trunk sewer main. This trunk main is sized sufficiently to collect all of the area within the contributing drainage zones as shown in the current Facility Plan. The subsequently created service area included all of the undeveloped properties that will utilize the trunk main. The City then created a payback district through a public hearing process before the Commission with all affected property owners being noticed. Adding the proposed developments to the Cattail Creek Zone may result in removing existing properties from that zone with two consequences for the Meadow Creek sewer and payback district. First, if properties are removed the main that was constructed will be larger than is required for the revised area. Excess capacity will improve operations, but excess capacity means that past developments paid for unnecessary over-sizing. Second, and more importantly, it could remove properties from the payback area that has been established. The area (exhibit attached) extends south to Patterson Road. The costs of the trunk main were spread evenly across the payback area so removing properties will alter participation in the payback area. (Note that the original developer defaulted on the project but the payback agreements were transferred to another entity that purchased them as an investment. Since these are created through an agreement between the developer and the City, at a minimum, the City would need to negotiate a new agreement with the “developer” if the boundaries are revised, and this would likely involve financial considerations). The issues outlined above demonstrate that requests from the Norton, Valley Center and Braxton developers to utilize existing rather than planned sewer collection capacity require careful consideration and planning. Staff believes that these requests will set a precedent that will negatively impact the efficiency of the entire wastewater collection system without carefully considering the long term impacts. However, these proposed developments exist in currently annexed lands and many of the properties they may displace in the existing Cattail Creek drainage basin are currently not annexed. Under the City's current approach to funding sewer infrastructure, it could be many years before enough coordinated development projects exist to construct the trunk main, lift station and force main. After careful review of the existing facilities plan and needs of current and future development, Staff recommends that the Norton, Valley West and Braxton developments be allowed to permanently connect to the existing collection system and utilize current available capacity in the Cattail Creek drainage zone provided that: All wastewater infrastructure be constructed to allow for proper permanent operation of the collection system. The developers will work with City Engineering staff to develop appropriate plans that meet City standards for all piping and lift stations. All lift stations will be required to provide backup power generation, full SCADA controls and utilize City standard wastewater pumps. The proposed connections are not permitted until an update of the wastewater facilities plan (estimated to cost $150,000) is initiated. The City must plan to minimize the impact of the 122 proposed developments on future projects. An update of the facilities plan will include a reevaluation of the drainage basins making modifications as necessary to minimize the impacts of the proposed projects on future development. In addition, the update will reevaluate the existing drainage basins to minimize the number of lift stations and force mains required for future development west of town. Finally, the update will provide firm predictions of the additional annexations and developments that can be accommodated by the existing collection system. The update will provide clear guidance on when new development must be stopped unless new collection infrastructure is constructed. Staff also recommends that the Commission reevaluate how major wastewater collection infrastructure is funded. Constructing the $13+ million systems required to provide the wastewater collection capacity required for continued growth to the west is unlikely using the current developer driven approach. Failure to construct the required collection infrastructure will result in the construction of haphazard wastewater systems, a development/annexation moratorium, or both. Staff recommends that the Commission consider debt financing the design and construction of the trunk line, lift station and force main, guaranteed with revenue bond and serviced with a combination of impact fees and rates. UNRESOLVED ISSUES: There are a number of even larger policy issues attached to facilitating development in the northwest part of the city by investing in the wastewater infrastructure there. Such dispersed developments will place a burden on the incomplete water and transportation networks in the far northwest and west parts of the city. FISCAL EFFECTS: As discussed above. ALTERNATIVES: Adopt Staff recommendations. Do not provide the ability for the proposed developments to utilize existing collection capacity Other alternatives as suggested by the Commission. Attachments: Figure 6-4 from the Wastewater Facility Plan Map of Proposed Developments Meadow Creek Subdivision Sewer Payback Zones 123 124 125 126