2024-0613 Roers Chanhassen - Sanitary Sewer Capacity Memo
kimley-horn.com 767 Eustis Street, Suite 100 St. Paul, MN 55114 651-645-4197
MEMORANDUM
To:
Mr. Charlie Howley, PE
Mr. Erik Henricksen, PE
City of Chanhassen - Engineering Department
From: Mike Brandt, PE
Kimley-Horn and Associates, Inc.
Date: June 13, 2024
Subject: Sanitary Sewer Capacity on Market Street
Kimley-Horn was requested to analyze the capacity of an existing 8-inch sanitary sewer line that
currently Serves the Cinema, The Venue Complex. Chanhassen Dinner Theater, and the Parking
ramp along Market Street. The sewer dead ends east of the parking ramp near Great Plains Blvd
and continues west in Market Street and through the existing parking lot to the Venue and Cinema
prior to turning south and crossing under the railroad. The pipe doe change to a 10-inch pipe when it
flows toward the railroad. To complete this analysis, Kimley-Horn utilized estimated flow data from
the Metropolitan Council of Environmental Services (MCES) Sewer Accessibility Charge (SAC)
Calculator to estimate the flows from each of the facilities. The flow data is used in a spreadsheet to
estimate sewage charges equal to a residential home. Under the SAC program, 1 SAC has an
equivalent flow rate of 274 GPD (gallons per day).
The table below outlines the current flows on the 8-inch sanitary sewer:
Location Number of Units SAC Unit per
Spreadsheet
Total amount of
SAC’s
The Venue Housing 134 Apartments 1 SAC / Apartment 134
The Venue Retail 18,725 SF 0.33 SAC / 1000 SF 7
The Venue Parking
Floor Drains
10 0.24 SAC / drain in a
parking garage
2.3
Dinner Theater 90,000 SF 1 SAC / 1,000 SF 90
Cinema 1,089 Seats 1 SAC / 64 Seats 17
TOTAL EXISTING SACS ON THE 8 INCH LINE 251
251 SACs * 274 GPD/SAC = 68,774 GPD
68,774 GPD * 1-day/24 hours * 1 – hour/60 min = 47.76 GPM
47.76 GPM * 1 min/60 sec * 1 CF/7.48 gallons = 0.11 CFS
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kimley-horn.com 767 Eustis Street, Suite 100 St. Paul, MN 55114 651-645-4197
The table below defines the proposed uses for the improvements to the Cinema Building:
Location Number of Units SAC Unit per
Spreadsheet
Total amount of
SAC’s
The Venue Housing 134 Apartments 1 SAC / Apartment 134
The Venue Retail 18,725 SF 0.33 SAC / 1000 SF 7
The Venue Parking
Floor Drains
10 0.24 SAC / drain in a
parking garage
2.3
Dinner Theater 90,000 SF 1 SAC /1,000 SF 90
East Apartment
Building
126 Apartment Units 1 SAC / Unit 126
East Building
Retail/Restaurant
1500 SF 3.33 SAC / 1,000 SF 5
East Building Parking
Floor Drains
10 0.24 SAC / drain in a
parking garage
2.3
Potential Additional
Housing Development
125 1 SAC / Apartment 125
Potential Additional
Retail/Restaurant
1500 SF 3.33 SAC / 1,000 SF 5
Potential Additional
Parking Floor Drains
10 0.24 SAC / drain in a
parking garage
2.3
Total Proposed SAC’s ON THE 8 INCH LINE 499
499 SACs * 274 GPD/SAC = 136,726 GPD
136,726 GPD * 1-day/24 hours * 1 – hour/60 min = 94.9 GPM
94.9 GPM * 1 min/60 sec * 1 CF/7.48 gallons = 0.21 CFS
Proposed SAC’s without redevelopment of the parking lot near the park and ride structure:
367 SACs * 274 GPD/SAC = 100,558 GPD
100,558 GPD * 1-day/24 hours * 1 – hour/60 min = 69.83 GPM
69.83 GPM * 1 min/60 sec * 1 CF/7.48 gallons = 0.16 CFS
To determine the maximum flow each of these facilities would likely produces, we apply a Peaking
Factor of 4. This peak factor is based on the Ten States Standards for sewer design based on the
low flows anticipated for these facilities.
• Existing Condition: 0.11 CFS * 4 = Peak Hour Flow of 0.44 CFS
• Proposed Condition: 0.16 CFS * 4 = Peak Hour Flow of 0.64 CFS
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kimley-horn.com 767 Eustis Street, Suite 100 St. Paul, MN 55114 651-645-4197
Looking at the capacity of the existing 8-inch sanitary sewer line, we know the following information:
• The existing 8-inch Sanitary sewer line from the east is at a 0.42% grade.
• The existing 8-inch sanitary sewer line connects to a 10-inch line that flows south under the
railroad tracks.
To analyze the pipe capacity, Kimley-Horn developed a spreadsheet to analyze the capacity of a 8-
inch sewer pipe at a 0.42 % slope. This spreadsheet determines the flows for the pipe flowing 50%,
75% and 100% full. Typically, sanitary sewer pipes area designed to flow at 50 % capacity for
average day flow and 75 to 80 % capacity for the peak hour flows. The table below shows the
capacity of the 8-inch sewer pipe at the different flow capacities compared to the flows estimated for
the project.
50% Full (CFS) 75% Full (CFS) 90% Full (CFS)
Pipe Capacity 0.39 0.72 0.84
Projected Flow Peak
Hour with additional
development
0.84 0.84 0.84
Projected Flow Peak
Hour with only Roers
added development
0.64 0.64 0.64
Based on our analysis, the existing 8-inch sewer pipe has adequate capacity to handle the proposed
average daily estimated flows. How ever during the peak hour the estimated flows with the east
building and the proposed addition to the parking lot near the park and ride facility consume the entire
8-inch line capacity. We would recommend if the area near the park and ride facility redevelops, the
existing 8 inch line be upgraded from the existing 10 inch line to just past the east building connection
of the Roers development to have adequate capacity in the line. The current 8-inch line has
adequate capacity until more development is added with the Roers proposed development.
Please give us a call if you have any questions or concerns.
Sincerely,
Michael C. Brandt, PE
Kimley-Horn and Associates