CR 98-09 Accept Report on Sanitary Sewer System AnalysisJanuary 2, 1998
Proposed Action.
Accept Report on Sanitary Sewer System Analysis
Council Report 98 -009
Staff recommends adoption of the following motion: Move that Council
accept the report on condition of existing sanitary sewer collection pipes in
areas which experienced sewer backups last year.
Overview.
In October, 97 staff developed an action plan to address last summer's storm
sewer and sanitary sewer problems in several areas of the city. City Council
adopted the action plan by resolution on November 5, 1997. The plan
included completing an analysis of the existing sanitary sewer pipes that serve
two areas of the City which experienced sewer backups. These pipes were
cleaned and televised during October and November The television
inspection report and video tapes have been reviewed by staff. No significant
problems were discovered.
Primary Issues to Consider.
• What were the results of the sewer cleaning and televising?
• Did existing pipe condition contribute to sewer backups?
• Are any follow -up city actions necessary?
Supporting Information.
• Action Plan excerpt
• Map showing sewer locations
• Television Inspection report results for one pipe section
• Utility Superintende t Memo
Steven J. Stadler, Public Works Director
Council Report 98 -009
Page 2
Analysis of Issues.
• What were the results of the sewer cleaning and televising?
The results showed nothing significant as far as problems affecting flow
capacity of these sewers. There were sections of pipe with varying degrees
of root infiltration and one section of 11 Avenue sewer with debris (sand).
There were no partial blockages or pipe structural problems (major cracks,
settlement or collapse). Television inspection report results for one section of
pipe are attached. This is provided to give an idea of the type of information
available on each segment of pipe in the full report. The full report is
available for City Council or public review.
• Did existing pipe condition contribute to sewer backups?
No. The cleaning and televising showed no evidence of blockages or flow
restrictions which would have contributed to a reduction in flow capacity of
these sewers.
• Are any follow -up city actions necessary?
No sections require pipe replacement. The pipe sections examined in this
analysis are obviously critical during high flow conditions - Public Works will
ensure that these sections are cleaned annually and roots removed, as needed.
4. North of Maetzold Field C. Complete capacity analysis of existing
continued) sanitary sewer collection pipes serving this
ea
D. Complete repairs to collection pipes, if
there are capacity problems because of
defective parts
5. Alley between 8th & 9th
Avenues North
6. 6th Avenue North/3rd
Street North storm sewer
project
7. Hobby Acres
8. 2nd Street Northeast &
Monroe Avenue North
— fkCTl o/V PG. 4A/ -_
E. Complete sump pump inspections of homes
and businesses in this sanitary sewer area
and analyze results
F. Disconnect any improper sump pump
connections in this service area
A Confirmation that the proposed 6th Avenue
storm sewer project will improve drainage
in this alley
A. Project design completion
B. Storm drainage improvement project
construction completion
A Capacity analysis of existing sanitary sewer
collectipn pipes serving this area
B. Complete repairs to any defective pipes
C. Complete sump pump inspections of
homes and businesses in this sanitary
sewer service area and analyze results
D. Disconnect any improper sump pump
connections that are found in this area
A. Complete analysis of drainage capacity for
this area
B. Complete construction of any necessary
improvements
DECEMBER
1997
DECEMBER
1998
MARCH 1998
NOVEMBER
1998
FEBRUARY
1998
FEBRUARY
1998
NOVEMBER
1998
DECEMBER
19917
DECEMBER
199!
MARCH 1998.
NOVEMBER
1998
FEBRUARY
1998
NOVEMBER
1999
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t7GHEN ENVIRONMENTACSERVICES
00- 0 1 :ER;19 97 :a';<::.'.
FIELD OBSERVATION :REPORT FOR PROjEC : HOPKWS,`M
October 31,1997,4:04 prn
Upstream Manhole
Pipe.Nurtiber;:, :.' z..ic c: :.. ':03-0010 `;` `:. �:,
StreetName Hazel Lane 1
Inspector ID Buchen
Starting Date/Time 10/14/97
Ending Date/Time 10/14/97
Ground Condition DRY
Weather Condition DRY
Paving Over Pipe ASPHALT
Percent ( %) Paved 100%
Pipe Material VCP
Pipe Diameter 8.0
Total Pipe Length 164.0
Joint Spacing 3.0
Camera Direction WITH FLOW
Flow Direction S
Depth from Rim to Invert:
Upstream Manhole 4.00
Downstream Manhole 7.50
Video Tape ID 97 -2
Tape Start Index 0:28:45
Tape End Index 0:32:30
Comments:
Downstream Manhole `
. 03 o0p9
Pipe # 4
CLOSED CIRCUIT TELEVISION INSPECTION
FOR
HOPKINS, MINNESOTA
BY
BUCHEN ENVIRONMENTAL SERVICES, INC.
OCTOBER, 1997
FIELD OBSERVATION REPORT FOR PROJECT: HOPKINS, MN
October 31, 1997 4:04 pm
Upstream Manhole
Pipe Number 03 -0010
Street Name Hazel Lane
Starting Date/Time ...... .. .... 10/14/97
Ftg Observation Inflt Rtng Clk Hse # Pic Jnt T Grout
0.0 UPSTREAM MANHOLE
2.0 ROOTS IN JOINT
4.0 ROOTS IN JOINT
13.0 WYE CONNECTION
66.0 WYE CONNECTION
75.0 ROOTS IN JOINT
81.0 ROOTS IN JOINT
81O BEGIN OBSERVATION
ROOTS IN JOINT
118.0 END OBSERVATION
ROOTS IN JOINT
131.0 ROOTS IN JOINT
136.0 BEGIN OBSERVATION
SAG_
160.0 END OBSERVATION
SAG ..
164.0 DOWNSTREAM MANHOLE
1
1
1
1
421.
3 103
Downstream Manhole
03 -0009"
Total Number of Observations 17 joints Tested 0
Total Infiltration (gpm) 0.0 joints Passed 0
Total Grout Amount 0.0 Joints Failed 0
D
PRINT DATE: October 31, 1997_406 pmK
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Memo
To: Steve Stadler Public Works Director
From: Michael G. Lauseng Utility Superintendent
Date: December 31, 1997
Re: Sanitary Sewer Information
0 Page 1
Hopkins Public Works
I have reviewed the information that Buchen Environmental Services, Inc. has provided to me and
after reviewing all the televising tapes, I have found that there are no structural defects in the sanitary
sewer pipe that would cause the sanitary sewer to back up. The only thing that would cause the flow
of sewage to back up in the system would be a large infiltration of storm water into the system. The
infiltration of large amounts of storm water probably came from leaking window wells, foundations and
sump pumps.
The areas that experienced problems this past summer have had similar problems only when there
has been either a major storm event or a broken water main or as in one case human error. The
following information is a history of what I have experienced in the 20+ years that I have worked here.
The area of north Hopkins that experienced sewer problems this past summer is part of the main
sanitary sewer collector of that area. I have seen this happen a couple of times in this area, once
during the early spring melt in the late 1970's we had a sanitary sewer problem that was caused by the
service station at Hwy. # 7 and Co. Rd. #73. The owner of the station at that time had a very large
water puddle in the western drive into his station and he went out into the puddle and opened what he
thought to be a storm sewer manhole and flooded the same area that had problems this year. We
received numerous calls about the sanitary sewer backing up in the 200 block of 13th Ave. No. first,
and then through out the area just shortly after. We started looking for the source of the water and the
further North we went the more water we found until we saw the manhole opened in the stations
driveway. The solution to the problem was to close the cover and the problem went away almost
immediately. The only other time that I can remember that this area was flooded was during the
heavy rain event in July, 1987 when just about every place in Hopkins had the same problem.
The area of Hobby Acres that had problems this summer also had a similar problem once when we
had a water main break in the Bridle Lane and Edgemoor Drive intersection. The water main broke
and the water went into the sanitary sewer Ijrae. The sanitary sewer could not handle that much extra
water and the area experienced problems very similar to what happened this summer Once we
found the source of the problem and shut down the main the sewer problem went away almost
immediately. The same thing happened during the heavy rain event of July, 1987.
The sanitary sewer in the Hazelane and Farmdale Road area is a collection point in the system that
carries the flows from the Dri llane and KnoMood areas as well as Hobby Acres into the main
interceptor.
Both of these systems function very well when they operate with in their design parameters
The problems begin when both systems are overloaded with infiltration and the design flows are
exceeded and then the system backs up. When this happens the lowest homes on the systems
experience problems. There is very little we can do when this happens and time usually will cure the
problem. I have enclosed drawings of flow districts # 3 and # 12 to show just how much area that is in
each district.
If you have any questions please feel free to contact me at 939 -1373 and I will try to answer them if I
can.
• Page 2
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