HomeMy WebLinkAbout[02] Executive SummaryExecutive Summary
1.0 Introduction
This 2009 Comprehensive Sanitary Sewer Plan (CSSP) for the City of St.
Joseph is intended to provide the overall planning and to be used as a guide
for the future expansion of the sanitary sewer system expansion within the
projected sanitary sewer service area. The scope of study for this CSSP is
outlying areas west and east of the City limits (see Figure 1). The CSSP is
general in nature and requires more detailed feasibility studies to determine
final flow estimates and locations of future facilities as the expansion areas
develop. Information from historical sanitary sewer flows was used to
determine aCity-wide diurnal curve. The background for this plan and the
Future Land Use Plan from the 2008 Comprehensive Plan Update, serves as
the foundation of anticipated flow quantities. A 9 square mile study area
(5,420 acres) was identified. By contrast, the current City limit is 4.07 square
miles in size.
Future flows were determined on a City-wide basis, using anticipated
wastewater flows for various land uses. The projected land uses, as opposed
to population estimates, have been used to determine future wastewater flows
in the collection system. The future flows for residential areas have a peaking
factor applied in accordance with the accepted `"Ten States Standazds". The
peak flow factor is the expected increase in water consumption and,
subsequently, wastewater production during high demand periods, such as
morning and evenings. The peak flows aze used as the basis for anticipating
the needed future capacity of lift stations and pipeline extensions in the study
azea. A minimum allowable sewer grade was used in sizing gravity sewers
(see Table 1). Additional analysis is needed to determine the adequacy of
existing infrastructure and any upgrades that may be required.
Estimated costs for trunk facility improvements 10-inch and lazger aze
included in this report. The cost estimates include contingencies and project-
related costs based on estimated 2009 construction costs. Accordingly, the
cost estimates do not represent the full extent of costs that may be incurred
due to unforeseen issues such as rock, groundwater, etc. Cost estimates are
provided to permit order of magnitude considerations for long range planning
purposes rather than feasibility study. estimates. The anticipated trunk sewer
system for 2059 would exceed $31 million.
The recommended actions include:
• Annually review and consider the appropriateness of sewer charges
and funding options.
• Monitoring the flows in the system for system upgrade timelines.
• Innplement lift station annual flow testing program to confirm station
pumping capacity and determine if any maintenance is needed.
• Develop a flow model to assess critical flow indications.
2009 Comprehensive Sanitary Sewer System Plan (CSSP)
St. Joseph, MN
Executive Summary (Continued)
Based on flow projections, the study boundary appears to be significantly
larger than a 20 yeaz plan, and possibly greater than a 50 year projection.
Given present day pipe materials, the typical design life of sanitary sewer
pipe may exceed 50 years. By following the recommendations of this report,
the City of St. Joseph should be able to manage the sanitary sewer flow from
future development for the next 50 years.
2.0 Scope
The City Council of St. Joseph authorized the preparation of this CSSP. The
purpose of this effort is to provide the City with a plan that provides
guidance for the expansion of the City's trunk sanitary sewer system to serve
the ultimate development within the study azea.
This CSSP focuses on ultimate development of the trunk sanitary sewer
system in the current City limits and surrounding areas (see Figure 1). Since
ultimate development will not occur for many years, interim improvements
may be necessary, depending on the rate at which development occurs in
each area.
This plan does not take the place of detailed feasibility studies that aze
typically prepazed prior to the design and construction of improvements. Due
to the global nature of this study, it is general and less specific than detailed
feasibility studies. Recommended improvements should be verified by
detailed feasibility studies to confirm sizes, locations, costs, and staging for
improvements.
The emphasis of this plan is the trunk sanitary sewer system. A trunk sewer
system generally includes lift stations, force mains, and all gravity mains 10
inches in diameter or larger.
3.0 Data Available
Some of the materials and information used in the preparation of this report
include:
• 2008 Comprehensive Plan Update
• Land use map provide by the City of St. Joseph
• 2-foot contour mapping provided by the City of St. Joseph
• Lift station sewer flow monitoring conducted by the City of St.
Joseph
• National Wetland Inventory Maps
• USGS Topographic Maps
• Development concepts available for new developments
2009 Comprehensive Sanitary Sewer System Plan (CSSP)
City of St. Joseph, MN