Tab 35. Wastewater Collection System Analysis - StarlingWASTEWATER COLLECTION SYSTEM ANALYSIS
STARLING
1-11: i N I
Prepared By:
MORRISON
� ► MAIERLE, INC.
An Emplo.Vee-Osvneel CompanY
MMI #: 3384.039
STARLING
WASTEWATER COLLECTION SYSTEM ANALYSIS
1.0 Introduction
The purpose of this report is to analyze the City of Kalispell's wastewater
collection system and its ability to meet future demands for the Starling
development.
The Aspen Group, doing business as Stillwater, LLC is proposing to
develop approximately 640 acres in Section 35. Specifically, the project is
bounded by West Reserve Drive to the north, Four Mile Road to the south,
Spring Creek Road to the west, and Stillwater Road to the east. See
Vicinity Map VM-1.
The overall development plan will consist up to 3,000 dwelling units
constructed in a minimum of 14 phases. The land uses offered will vary
from single family homes, multi -family paired homes, condominiums,
townhomes, mixed use commercial including professional office and a
parcel identified for a new elementary or junior high school. The number
and types of housing units constructed will be determined by market
conditions at the time each phase develops.
2.0 Existing Conditions
Wastewater service will be provided by the existing City of Kalispell
wastewater collection system. There are two options for Starling to
connect to the system:
® Existing 12" gravity main at the intersection of Stillwater Road and
West Reserve Drive.
* Existing sewer mains located in Stillwater Road and Three Mile
Drive to the south of the property.
I
STARLING WASTEWATER IMPACT REPORT
It is anticipated that the initial six phases of Starling will connect to the 12-
inch gravity main at Stillwater Road and West Reserve Drive. This sewer
main was installed in 2004 under a Late -Comers Agreement (LCA)
between the City of Kalispell and Owl Corporation to serve other
development in the area, and is oversized to accommodate other
surrounding properties, including Starling. This main currently has
approximately 872 equivalent dwelling units (edu) of capacity remaining.
From this connection point, wastewater will be routed through the existing
collection system to the City of Kalispell Wastewater Treatment Plant.
The wastewater treatment plant has adequate capacity to serve the first
phases of this project; and construction to nearly double the capacity of
the plant will begin in 2007. Upon final completion of the Starling project,
the Treatment Plant will have adequate capacity to serve the entire
community.
The City is also revising their Capital Improvements Plan to reflect recent
development patterns. It is very likely some offsite wastewater system
improvements, such as installation of larger mains, will occur as a result of
the new plan. These revisions could allow for better wastewater service to
Starling and surrounding developments. Since the updated plan is not yet
completed, it is difficult to anticipate any other offsite improvements at this
time.
3.0 Proposed Demands — Starling
The project has been divided into 15 phases for the purpose of analyzing
the flows generated from the development and the relation of those flows
to the capacity of the existing system. The 15 phases are shown in the
attached Figure 1-1.
2
STARLING WASTEWATER IMPACT REPORT
The City of Kalispell design standards require the following criteria for
estimating wastewater demands:
i 100 gallons per day per acre for infiltration
6 87 gallons per person per day per resident
O 20 gallons per day per employee for commercial
In accordance with the City of Kalispell's Facilities Plan 2000, the census
data states there are an average of 2.41 people per home in Kalispell.
The Montana Department of Environmental Quality also requires the
design of the sewer system to be based on the peak hourly flow. This flow
is determined by the following equation:
14+-IfT
�Pliell: 1$.UtP — ��:II'1;71.Ki/:1•'LU IY$
4+I/P
where P is the estimated population in thousands of people. Based on an
estimated population of 7,230 residents, a peak hour/average day factor of
3.09 should be used for the entire project.
3
STARLING WASTEWATER IMPACT REPORT
Table 1 summarizes the estimated wastewater flows for Starling:
Table 1
Estimated Wastewater Flow
Phase
Acres
Number
of Units
Average Day
Flow
Peak Hourly
Flow
Infiltration
Total Peak
Flow
gpm
gpd
gPm
gpm
gpd
gpm
1
57.0
223
32.4
46,756.4
123.2
4.0
5,700
127.2
2
28.3
208
30.3
43,611.4
115.8
2.0
2,830
117.8
3
24.5
162
23.5
33,966.5
91.5
1.7
2,450
93.2
4
34.0
237
34.5
49,691.8
130.6
2.4
3,400
132.9
5
26.8
229
33.3
48,014.4
126.4
1.9
2,680
128.2
6
21.2
149
211
31,240.8
84.9
1.5
2,120
86.4
7
46.3
180
26.3
37,740.6
101.6
3.2
4,630
104.8
8
32.2
161
23.5
33,756.9
91.5
2.2
3,220
93.7
9
34.5
167
24.3
35,014.9
94.4
2.4
3,450
96.8
10
73.6
215
31.3
45,079.1
119.4
5.1
7,360
124.5
11
36.5
224
32.6
46,966.1
123.9
2.5
3„650
126.5
12
40.0
161
23.5
33,756.9
91.5
2.8
4,000
94.3
13
56.2
190
27.6
39,837.3
106.2
3.9
5,620
110.1
14
48.8
140
20.4
29,353.8
80.2
3.4
4,880
83.5
15-Mixed
15
--
3.3
4,752.0
13.2
1.0
1,500
14.2
15-School
15
--
8.7
12,500.0
27.9
1.0
1,500
28.9
TOTAL:
590
397.2
572,038.8
1,522.20
41.0
58,990
1,563.2
In summary, the total peak hourly flow from the project (including
allowances for infiltration) is estimated to be approximately 1,563 gallons
per minute. The estimated average daily demand from the project
(including infiltration allowances) is 631,030 gallons per day (GPD).
For the mixed use area, the wastewater demand assumes two restaurants
and two retail centers will be constructed. Restaurants are estimated to
produce 2,000 GPD per business and retail centers 350 GPD per center.
The school demands are based on a population of 500 students, each
producing 25 GPD.
4
STARLING WASTEWATER IMPACT REPORT'
4.0 Proposed Improvements
Each proposed sewer main in the project was sized in accordance with
the flows calculated above and assuming they are installed at the
minimum grade. The sewer main layout for Starling is shown in Figures 1-
2 and 1-3. The minimum sewer main size within the development will be
8-inch diameter per the City of Kalispell and MDEQ Standards.
4.1 Lift Stations
Wastewater in Starling will be routed to one of the two proposed Lift
Stations. The lift stations will pump the wastewater into the existing City of
Kalispell's wastewater system. Lift Station locations and service area can
be seen on Figure 1-4.
4.2 Service Area and Wastewater Flows
Starling Lift Station A: This proposed Lift Station will provide service to
the first six phases of Starling. The phase boundaries are also shown on
Figures 1-2 and 1-3. Lift Station A will pump wastewater through an fl-
inch force main into the existing 12" gravity sewer main at Stillwater Road
and West Reserve Drive.
Table 4-1 shows the estimated demands placed on this lift station after the
completion of Phase 6. The number of dwelling units in phases 2-6 was
estimated using an average lot width of 40 feet. Phase 1 was estimated
using the proposed lot count from the proposed Phase 1 Preliminary Plat.
5
STARLING WASTEWATER IMPACT REPORT
TABLE 4-1 LIFT STATION
"A" WASTEWATER FLOWS BY PHASE
NUMBER OF
AVERAGE DAILY
PEAK HOURLY
PHASE
LOTS
FLOWS
FLOWS
GPM
GPM
1
239
34.8
136.1
2
208
30.3
104.6
3
162
23.5
81.3
4
237
34.5
119.1
5
229
33.3
115.1
6
149
21.7
75.0
Total
1207
178.1
631.2
Starling Lift Station B: This proposed Lift Station will provide service to
the remaining phases as well as the mixed use and school property.
Wastewater will be pumped into the City of Kalispell collection system at
one of the following locations:
• Into the existing main at Stillwater Road and West Reserve Drive
(See Figures 1-1 and 1-3 "Force Main Alternative 1")
• Into the existing main at Stillwater Road south of Four -Mile Drive
® Into a proposed sewer trunk main located in the highway bypass
right-of-way. (See Figures 1-1 and 1-3 "Force Main Alternative 2)
The outlet location of this force main will be determined by the conditions
of the City wastewater collection system when this lift station is ready to
19471
Table 4-2 shows the estimated demands placed on this lift station after
build out of all phases is complete.
STARLING WASTEWATER IMPACT REPORT
TABLE 4-2 LIFT STATION B WASTEWATER FLOWS BY PHASE
NUMBER OF
AVERAGE DAILY
PEAK HOURLY
PHASE
LOTS
FLOWS
FLOWS
GPM
GPM
7
180
26.3
88.9
8
161
23.5
79.4
9
167
24.3
82.4
10
215
31.3
106.0
11
224
32.6
110.3
12
161
23.5
79.3
13
190
27.6
93.4
14
140
20.4
69.0
School
--
8.7
27.9
Industrial
Park
—
3.3
13.2
Total
1441
221.5
749.8
5.0 Off Site Impacts and Conditions
The area north of Kalispell is rapidly growing, and this growth is beginning
to stress some existing facilities within the City of Kalispell collection
system. The developers of Starling realize their project, coupled with all
other developments north of Kalispell, will have significant impacts to the
existing system. As a result, the developers have created a phasing
schedule showing the effects Starling will have on the existing collection
system. This schedule is shown as a part of the PUD submittal.
Improvements related to wastewater collection are shown in the table
below:
It should be noted the improvements listed in Table 5-1 were compiled
using up to date data provided by the City. However, the updates to the
City Capital Improvements Plan have not been completed at the time of
this report. Therefore, some of the listed improvements may change
depending on the information contained in that report.
7
STARLING WASTEWATER IMPACT REPORT
TABLE 5-1: OFF -SITE SEWER IMPROVEMENTS
Phase
Improvement
Description of Upgrade
1
Grandview
Upgrade pumps in the Lift Station to increase capacity in the
Lift Station
system
Increase
Install a new sewer main or increase the size of the sewer mains
1
Main
in Summit Ridge and Parkview Drive, approximately 1500 If
Capacity
upgrade
Increase
Upgrade sewer main in Liberty Drive, approximately 3000 feet
3
Main
upgrade from 8" to 12" (City identified this as a "potential"
Capacity
problem)
4
Increase
Main
Upgrade main in Section 36 north of Glacier Meadows with
Capacity
approximately 2600 feet of new main
4
New Lift
Installation of a regional lift station to route wastewater from new
Station
growth from the north to the wastewater plant
5
Increase
Main
Upgrade main in Section 36 below high school with
Capacity
approximately 1000 feet of new main
crea6 lnMMain
a
Increase capacity of sewer main in West Reserve Drive from 12"
Capacity
to 18", approximately 3000 If
7
New Sewer
Installation of sewer collection main in the bypass right of way,
Main
approximately 4.66 miles
This table corresponds to the schedule of off -site improvements presented
in the PUD submittal.
STARLING WASTEWATER IMPACT REPORT
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