HomeMy WebLinkAbout[04] 2009 CSSPOctober 1, 2009
2009 Comprehensive Sanitary Sewer System
Plan (CSSP)
Prepared for City of St. Joseph
1.0 Introduction /Methodology
The City of St. Joseph is a community having a 2008 population of 6,156 people,
based on the estimates supplied by the United States Census Bureau. The St. Cloud
Area Wastewater Treatment Facilities plan forecasts that by the yeaz 2030 the City
will have a population of approximately 15,753 people.
The following sanitary sewer collection system plan is intended to become part of
an overall Comprehensive Plan for the City which provides the technical
documentation to support the long range sanitary sewer collection system planning
efforts.
To evaluate expansion of the sanitary sewer collection system, the study area was
divided into sanitary sewer drainage districts. The boundaries of the districts aze
correlated with projected development plans and the natural topography. A map of
the sanitary sewer districts is contained in Figure 3.
Treatment of wastewater is provided by the City of St. Cloud at its wastewater
treatment plant. Wastewater is presently pumped from St. Joseph in a force main
located along County Road 75 where it enters the St. Cloud Sewer Interceptor
System just north of the Tri-City Lift Station in Waite Park. The present average
daily flow from St. Joseph to the St. Cloud interceptor system is approximately
0.377 million gallons per day (MGD). Based on the draft 2008 St. Joseph
Comprehensive Plan population projections, St. Joseph will convey an estimated
average flow of 1.58 MGD in 2030.
The study area includes the outlying areas of St. Joseph as well as azeas identified in
the 2008 Comprehensive Plan Update. The entire study area is approximately 9
squaze miles in size (see Figure 3, Sanitary Sewer District). The azea studied
includes future areas adjacent to the City of St. Joseph that, from a utility
perspective, could be served by the City's sanitary sewer system. Connections to
other municipalities, as well as areas outside of the districts shown in Figure 1, were
beyond the scope of this analysis. Areas shown outside the sewer districts identified
in Figure 3 aze excluded because they were previously studied, served by the
existing sanitary sewer system, or still need to be studied but were outside the scope
of this study.
STJOE 17564
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In order to estimate anticipated wastewater flow rates, the Future Lands Use Plan is
used to classify the area of each sanitary sewer district into different land use types.
Each land use type has associated with it an estimated future flow wastewater rate
per developable acre. Population projections are not used to determine future flows
for the collection system. The contributing azea used to determine wastewater flow
rates is measured in total developable acres.
1.1 Design Criteria
Anticipated wastewater flows from various districts are calculated by applying the
unit flow rates for each land use type to the developable acreages within the
districts. The flow rates were determined based on the average number of people per
household and recent platting densities. The flow rates are assigned according to
Table 1.
The flow capacities of trunk sewer lines aze calculated using accepted technical
procedures: gravity sewers are based on pipe size and slope. Pumping station sizes
aze based on pump operating curves and head loss (loss of pipe fluid energy).
To allow some margin for planning change and operations, it is recommended the
design/planning capacity for pipe sewers be based on a maximum of 85 percent of
the "full-flow" capacity for the facilities.
The unit and azea flow rates are presented in Table 1.
Table 1
Unit and Area Wastewater Flows
GaU
Units/ Person People/
Land Use T e Acre /Da Unit Gal/Acre/Da
Single-Family Residential 3.0 100 2.74 822
(Low Densit )
Multi-Family Residential 4.0 100 2.74 1096
(Medium Densit )
Multi-Family Residential 14.0 70 2.00 1960
(Hi h Densit )
Commercial/Industrial N/A N/A N/A 2000
A platting loss of 15-percent is applied to all acreage to account for road right-of-
way, parks, wetlands, and storm water ponds.
The trunk sanitary sewer facilities must be capable of handling not only the average
flows, but also anticipated peak flow rates. Applying a variable peak flow factor to
the average flow approximates these peak flow rates. As the population in a given
azea increases, the peak flow factor decreases. This factor is calculated by a standard
formula presented in the Ten States Standards' Recommended Standards for
Wastewater Facilities 2004 Edition.
The peak factor only applies to residential flows. Non-residential flows are typically
not susceptible to large variations in flow; therefore, peak flows aze not applied to
non-residential flows. The peak flow factor used for the planning districts is 2.5.
2009 Comprehensive Sanitary Sewer System Plan (CSSP) STJOE 17564
St. Joseph, MN Page 2
2.0 Collection System
2.1 Future Sewer Districts
The proposed sewer districts are grouped according to the proposed lift station to
which the district (sewer shed) flows. The future districts consist of 24 lift stations.
Figure 3 illustrates the sewer districts.
2.1.1 Future Northeast Sanitary Sewer District (Lift Station 1-5)
This district encompasses all areas northeast of the existing City. It is anticipated to
include 673 acres of residential development and 442 acres of additional
commercial/industrial development. The district is divided into subdistricts LS1-
LSS.
DISTRICT
Low Medium High
Density Density Density
Residential Residential Residential Commercial Industrial
Subdistrict (acre) (acre) (acre) (acre) (acre) Notes
LS 1 131 69 81 95 Flow by gravity to a new lift
station near Rolling Ridge Road
and 73`d Avenue North.
LS2 26 3 85 175 Flow by gravity to a new lift
station near Pearl Drive and Delta
Circle.
LS3 46 44 50 Flow by gravity to a new lift
station southeast of Mullen Road
and County Road 133.
LS4 153 33 Flow by gravity to a new lift
station on the south side of 320m
Street.
LSS 37 86 Flow by gravity to a new lift
station near the location where
Jose~h Street would intersect
315 Street.
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St. Joseph, MN Page 3
2.1.2 Future South East Sanitary Sewer District (LS6-LS7)
This district encompasses areas southeast of the existing City near the Sauk River. It
is anticipated to include 236 acres of residential development and 92 acres of
additional commercial/industrial development.
DISTRICT
Low Medium High
Density Density Density
Residential Residential Residential Commercial Industrial
Subdistrict (acre) (acre) (acre) (acre) (acre) Notes
LS6 161 28 9 63 Flow by gravity to a new lift
station near the future 24`~
Avenue SE and I street location.
LS7 38 29 Flow by gravity to a new lift
station near the future 26`~
Avenue SE and Able Street
location.
2.1.3 Future Northwest Sanitary Sewer District (LS8, LS19-LS20)
The future northwest sanitary district is a large district on the northwest side of the
City. It is anticipated to include 578 acres of residential development and 764 acres
of additional commercial/industrial development.
DISTRICT
Low Medium High
Density Density Density
Residential Residential Residential Commercial Industrial
Subdistrict (acre) (acre) (acre) (acre) (acre) Notes
LS8 296 50 93 164 Flow by gravity to a new lift
station near County Road 2 and
north corridor alignment.
LS 19 20 155 125 Flow by gravity to a new lift
station near County Road 74 and
the crossing of the south fork of
the Watab Creek.
LS20 3 4 2 115 125 Flow by gravity north of I-94 to a
new lift station near Ash Street
West extension and the
realignment of County Road 2.
2009 Comprehensive Sanitary Sewer System Plan (CSSP) STJOE 17564
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2.1.4 Future Southwest Sanitary Sewer District (LS9-LS17, LS21-LS25)
The future southwest sanitary district is also large district on the southwest side of
the City extending to 133`d Avenue (western limit of St. Joseph Township). It is
anticipated to have 1,418 acres of residential development and 381 acres of
additional commerciaUindustrial development.
DISTRICT
Low Medium High
Density Density Density
Residential Residential Residential Commercial Industrial
Subdistrict (acre) (acre) (acre) (acre) (acre) Notes
LS9 129 District LS9 consists of the
undeveloped property within
the College of St. Benedict.
Development of this project is
dependent on the College of
St. Benedict.
Flow by gravity to a new lift
station near the Field Street
Extension and 3`d Avenue SW.
LS 10 72 98 Flow by gravity to a new lift
station near N Street and 3`~
Avenue SW.
LS 11 168 4 Flow by gravity to a new lift
station near R Street and 3`~
Avenue S W.
LS 12 63 Flow by gravity to a new lift
station near T Street and 117'
Avenue SW.
LS 13 129 Flow by gravity to a new lift
station neaz N Street and 16~'
Avenue SW.
LS 14 67 103 Flow by gravity to a new lift
station neaz the southern
boundary line of St. Joseph
Township and County Road 2.
LS 15 202 124 198 Flow by gravity to a new lift
station near I-94 and County
Road 2.
LS 15 will be one of the main
lift stations serving the
southwest side of I-94. LS 14,
LS 16, LS21, LS22, and LS24
discharge into district LS 15.
LS 16 353 Flow by gravity to a new lift
station neaz 287` Street and 123`d
Avenue.
2009 Comprehensive Sanitary Sewer System Plan (CSSP) STJOE 17564
St. Joseph, MN Page 5
DISTRICT
Low Medium High
Density Density Density
Residential Residential Residential Commercial Industrial
Subdistrict (acre) (acre) (acre) (acre) (acre) Notes
LS 17 66 Located along the north side of
Kraemer Lake.
Flow by gravity to a new lift
station at the end of South
Karlyn Road.
LS21 87 Serves the existing residents
along the eastern edge of
Kraemer Lake and future
development to the east.
Flow by gravity to a new lift
station near Kraemer Lake
Road and 295`s Street.
LS22 52 1 159 Serves the east and west sides
of County Road 2 from just
north of 29~' Street to just
south of 287` Street.
Flow by gravity to a new lift
station just on the west side of
County Road 2 between 295`
Street and 287`x' Street.
LS23 74 Serves an isolated portion of
land on both sides of Kelp
Road south of I-94.
Flow by gravity to a new lift
station near Kelp Road and I-
94.
LS24 28 Serves an isolated portion of
land in the southwest corner of
St. Joseph Township.
Flow by gravity to a new lift
station on the east side of
Zimmer Lake.
LS25 24 Serves an isolated portion of
land on west side of Kelp Road
south of district LS23.
Flow by gravity to a new lift
station north of the future
intersection of 287' Street and
Kelp Road.
2009 Comprehensive Sanitary Sewer System Plan (CSSP) STJOE 17564
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2.2 Conveyance
Currently, the City of St. Joseph owns 5.24 MGD of conveyance through the St.
Cloud Sewer Interceptor System from the Tri-City Lift Station to the wastewater
treatment plant (WWTP). A portion of the conveyance through the City of St.
Joseph is utilized by the College of St. Benedict. When phases 1 and 2 construction
is complete as described in the City of St. Cloud 2007 Wastewater Treatment
Facilities Plan, the 2030 WWTP flow capacity for St. Joseph will be 1.72 MGD.
The 1.72 MGD flow corresponds with St. Joseph's projected population of 15,753
for the year 2030. Beyond 2030, the City will need to purchase additional treatment
capacity at the WWTP. As the City gets closer to fully developing the study area,
there will also be a need to purchase additional conveyance or find an alternative
route to the St. Cloud WWTP. One such alternative is to pump wastewater collected
west of I-94 directly to the St. Cloud WWTP. The City will need to work
extensively with landowners to obtain easements if this option is chosen.
2.3 Critical Flow Locations
One of the primary goals in this report is to identify critical flow locations (pipe
capacity limitations) in the future collection system study area and to position the
City to address them when development. occurs.
One immediate critical location is the existing sanitary sewer crossing of County
Road 75 just upstream of the City's main lift station. There are two identified
options to deal with the problem:
1. To accommodate present flows and to accommodate near-term development
in the vicinity of the County Road 2 realignment and I-94 corridor, the
existing County Road 75 crossing should be increased to a 30-inch pipe. It
should be understood that selection of this option is an intermediate solution
and will not provide enough pipe capacity to serve the entire planning
district, but recognizes another destination for treatment of the wastewater
in the planning district may develop in the future (likely beyond the 50-year
projection).
2. As development expands further southwest of I-94, the County Road 75
crossing must eventually be increased to a 42-inch pipe as illustrated on
Figure 3. Sanitary sewage west of I-94 will be pumped across I-94 to a
gravity line that drains to the main lift station. With this option, any
additional sewage above the City's 5.24 MGD conveyance capacity with the
City of St. Cloud will need to acquire additional conveyance capacity or
find another source for treatment.
3.0 Wastewater Treatment Plant
St. Joseph's wastewater is treated by the St. Cioud WWTP. The present plant has an
average annual daily flow of 10.18 MGD. Currently, St. Joseph pumps about 0.377
MGD to the WWTP and has an agreement with St. Cloud for Phase I of the WWTP
expansion for treatment capacity of 1.11 MGD. For the existing population, the
current sewage flow equates to approximately 75 gallons per person, per day.
To estimate the expected increased wastewater treatment needs, population growth
projections are commonly used. These population estimates come from the recent
update to the St. Joseph Comprehensive Plan.
2009 Comprehensive Sanitary Sewer System Plan (CSSP) STJOE 17564
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Assuming the comprehensive plan population projections, as well as a planning flow
per person of 100 gallons per day, the WWTP will reach 80 percent capacity in 2024
with a population of about 13,750, and full capacity in 2035 with a population of
about 17,200. These projections can be seen in Table 2. Table 2 below shows the
population and wastewater projected flows for the 5-year planning intervals.
Table 2
Projected 5-Year WWTP Flows
Year Po ulation WWTP Flow
2010 5,558 0.556
2015 12,777 1.278
2020 12,808 1.281
2025 13,908 1.391
2030 15,753 1.575
As the treatment capacity nears 1.72 MGD, the City should consider purchasing
additional treatment volume from St. Cloud.
4.0 Funding
4.1 Trunk System
The City of St. Joseph relies on two mechanisms to fund sanitary sewer related
projects. WWTP expansion related costs are covered by SAC fees. Interceptor and
lift station system expansions are funded through area trunk fees.
5.0 Recommendations
5.1 Collection System Expansion
Expansion of the existing collection system will be necessary to accommodate some
of the future areas shown in Figure 1. The existing system will need to be analyzed
to determine the adequacy of additional sewer shed areas. Future extensions will be
development-driven and should be sized to serve the proposed development, as well
as the azea surrounding it.
6.0 Conclusion
The City of St. Joseph sanitary sewer collection system has the ability to expand to
serve azeas in the Comprehensive Planning Districts. The next steps that need to be
taken in order to maintain a high level of service for current and future residents
include:
• Develop a flow model of the existing system to assess critical flow
locations.
• Monitoring the flows in the system for system upgrade timelines.
• Implement a lift station annual flow testing program to confirm station
pumping capacity and to assist in determining maintenance needs.
2009 Comprehensive Sanitary Sewer System Plan (CSSP) STJOE 17564
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