7.e2 Smoke testing Uptown SewerSCANDIA
Staff Report
Date of Meeting: June 16th, 2020
To: Mayor, City council
From: Adam Hawkinson, Director of Public Works
Re: Uptown Smoke testing sewer system
Background:
The Uptown system has nine billable customers on the system. An evaluation of the pump
readings, water meter readings, and pump readings at the drain field are indicating accurate
flow rates are not being recorded. According to the numbers the system is allowing some
infiltration.
Issue:
Not able to report accurate flow numbers for the Uptown system. The City council and
community needs to be notified of the process and practice PW is planning to initiate with
smoke testing. A 7 - 10 -day notice is required by MNRWA to perform the testing. This
discussion would service as a notice.
Proposal Details:
The Director of PW would like to conduct a smoke test on the system to check for leaks or
possible abandon lines that have not been capped. The Fire department and all connected
service owners would be notified by a letter similar to the draft provided. The dates are subject
to change. Information about the smoke process and procedure is provided with this report.
Fiscal Impact:
$100-$150 - performed by MN Rural Water Association.
Options:
1.) Perform the test and acknowledge the notification
2.) Do not perform the test
Recommendation:
Option #1
Smoke Testing the Sanitary sewer
To the residents of Scandia:
The City of Scandia will be smoke testing the sewer on your block the week of July
13th through the 17t". Should you notice any smoke in your business or home
please let the person testing of the City know immediately.
By smoke testing the line, the City will also be testing the service line form your
home or business at the same time. The presence of smoke in your home of
business is an indication that there is a leak and the sewer gases could also be
entering your structure.
The smoke is relatively harmless, but if you have a medical condition that smoke
might affect you, please contact the City at 651-433-2274.
Thank you,
Adam Hawkinson
Director of Public works
INFLOW ANALYSIS
Leaks permitting storm/surface water intrusion (inflow)
Connected roof and cellar drains
L' Cross connected sanitary and storm sewers
All connected lines, including abandoned and supposedly
unconnected lines
Leaking manholes
Yard and foundation drains
I Sump pumps
A high reading on treatment plant flow gauges during or imme-
diately following rainfall is a positive indication of storm/surface
water inflow. Smoke testing is the fastest, most economical
and positive means of locating sources of inflow in sewer
collection systems. Elimination of these sources, as required
by law, will improve treatment plant operations — and correct
problems of overloading which are a major contributor to pollu-
tion of water resources.
RECOMMENDED EQUIPMENT
Two each Superior Smoke No. 3C (three minute) are required
for each test consisting of two sections of fine generally 600-
800 feet of 8-12" pipe. Professional testing crews often prefer
Superior Smoke No. W3C that can be easily connected together
for longer search time.
A portable air blower with a capacity of between 1500 and
2000 cfm is required. A blower of lesser capacity will not
generate sufficient pressure to disclose all faults in a line and a
blower with greater than 2000 cfm may blow wafer from traps.
Recommended Blowers are the Superior Models 20-S ("FIG. 1)
or 10-S.
Other items required include line plugs and sand bags (partly
filled with % round stones with an attached rope for easy
positioning) and canvas or rubber flaps for confining the smoke
in specific sections of line.
Material for sketching location of faults to complete engineering
reports, and a Polaroid camera or equivalent are also needed.
For information on advance notice -- see specific head-
ing below for details.
Aam4
1
Y -
FIG. y — Superior Slower Model 20-S for sewer collection systems.
HAINOR WIRE
OOK
LABEL
SMCkrz EMMISSION I4OLES
FIG- 2 — Aiinetrinr Amoke Item s11cnanHPd On honk
SMOKE, _
BLOWERS
SMOKE'.'-
f
MANHOLEy
�ylANiiOiE
�fIAAIHOLEaj
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' SND BAGS'- - t y -,STOPPER7-1
F1 G. 3 — Schematic of smoke testing. Sand bags or line plugs can De
used to isolate sections of main.
PROCEDURE
F-XISTIIUG CONSTRUCTION
As illustrated in FIG. 3, usually two sections of line (600-800
ft.) are tested simultaneously, with the smoke being introduced
through a centrally located manhole, Blocking the far side of
the upstream and downstream manholes is only necessary
when isolating a section of fine. The smoke under pressure will
quickly fill the main plus all connected lines, and follow the path
of least resistance. It will flow through all main openings to the
surface, revealing the location of the faults. Invariably, the fault
will be found at the site or within a few feet of it. Only enough
pressure to sufficiently overcome atmospheric pressure is re-
quired,
Smoke tests are effective, regardless of surface, type of soil, or
depth, provided openings exist for the smoke to follow. For
example, it is not uncommon to see smoke exiting from cracks in
paved surfaces, showing points of surface water entry.
Best results are obtained on dry days when water is not leaking
into the line. (Other methods may overlook many sources of
inflow, unless the passing camera picks up water actually
leaking into the line).
The blower should not be started over the manhole because of
the possibility of igniting flammable vapors in the line, The
blower should be started first and then placed over the man-
hole. If line plugs are being used, do not tighten them before
the smoke has fully penetrated the line, otherwise trapped air
may prevent complete penetration.
Smoke may be induced through the intake of the blower.
Smoke items may also be suspended on a wire or pail beneath
the blower. This keeps the blower clean and in top operating
condition. Superior blowers are equipped with a chain and hook
for suspending smoke items in manholes (FIG. 2). The hook is
inserted into one of the holes running lengthwise on the side of
the smoke items. In less than a minute, smoke will be issuing
from the roof vent* of buildings connected to the line.
The crew should check building, grounds and streets for tell-
tale signs of smoke. Smoke immediately backing up into the
blower indicates a line blockage. If this should occur, testing
should be discontinued until the line has been cleared. Smoke
issuing from the ground, pavement, yards, roof drains, etc..
shows sources of inflow. Record for future repair,
ADVANCE NQTICF
Press releases to the news media (newspapers, radio and TV)
will generate much public good will and support for a prograrn
that will improve the local sewerage system, and assure corn-
pliance with EPA regulations. Such releases should outline the
program and call attention to what can be expected to take
place, as well as the problems that will be solved by having the
errFnlca Iaatinn rinno
Budget: The Superiors Smoke Testing Technique costs only a fraction of most otherinspection methods. Total initial investment
for all equipment will typically be under $3,OOD, and often less than $2,000 as usually some of the equipment is already on hand.
The consumables — either Classic Smoke Candles or Smoke Fluid -- are also very inexpensive. The total cost of amortized
equipment and smoke products should be well under 3 cents per linear foot of Main tested. Labor is variable depending on
local costs and productivity, but would likely be in the range of 10 to 20 cents per linear foot_ Total Budget therefore — including
Equipment, Smoke, and Labor is typically a total asst of only 16 to 20 ceras per ilnearfoot of Sewer gain.
Pe a : The Superior" Smoke Testing Technique is relatively simple and can easily be performed by 2-3 regular maintenance
crew members once they are trained in Smoke Testing. This small crew can easily test 30,000 linear feet of sewer main line in
an eight-hour shift, with just the simple equipment listed below.
EguipM : A Smoke Blower designed to sit on and blow into an open manhole, with 1504 to 2000 CFM capacity is ideal for
most situations. Up to 4504 CFM may be used for larger systems or longer runs, however more than this is not recommended.
The objective is to generate adequate smoke flow to find the faults — excessive flow can dilute the smoke, bypass faults,
blow out traps, and result in a less effective test. Superior' Smoke Blowers #10, #20, and #30 are all designed to meet these
requirements, and have been engineered specifically for Smoke Testing. Each of these Blowers can be configured to use Smoke
Fluid and/or Classic Smoke Candles. Other recommended equipment includes:
• Superior" Smoke Candles or Superior® Smoke Fluid.
• Digital Camera -- to document leaks and their location.
• Work Sheets or Paper—to document and/or sketch faults and related information.
• Stakes, Flags, and/or Paint — to mark faults and their location.
• Line Plugs, Stoppers, Sandbags, or Rubber/Canvas Flaps — to block off or contain Smoke.
• Smoke Testing Advance Notification and/or other Handouts -- for building occupants.
Haw Smoke Testing Works: Sewer Mains should be broken down to
two sections of line between 600-800 feet. Usually the two sections of
line are tested simultaneously, with the Smoke being introduced through
.(+'f a-1NAT4tk0k�- � J T.IAANHA4i
a centrally located manhole. This requires 5 to 6 minutes of Smoke x�
generation to provide enough time to walk the test area. Blocking the
far side of the upstream & downstream manholes is not required, but is ,
recommended for optimum results — and to prevent Smoke going beyond
the intended test area. Smoke under pressure will quickly fill the Main
and all connected lines and laterals, following the path of least resistance.so#�
Only enough pressure to sufficiently overcome atmospheric pressure is ftir saHrr cs s 5 �i9£
required — Smoke will flow through all openings to the surface, and should
come out roof vents throughout the test area. Any Smoke not from a proper vent indicates a fault where surface water can flow
into the Sanitary Sewer. Smoke tests are effective regardless of surface, type of soil, or depth, provided openings exist for the
Smoke to follow. For example, it is not uncommon to see Smoke exiting from cracks in paved surfaces or lawns, showing points
of surface water entry.
Smoke IsAina Procedure: The blower should be started first, and then placed over the manhole to safely vent potentially
flammable sewer gasses. Run the blower for a minute or two to establish a flow, and there introduce the Smoke — in less than
a minute, Smoke will be issuing from the roof vents of all buildings connected to the line. The crew should immediately walk
throughout the test area, checking buildings, grounds, and streets for any signs of Smoke. Any faults indicated by Smoke
should be immediately photographed and documented. if plugs are being used, do not tighten them before the Smoke has fully
penetrated the line, otherwise trapped air may prevent complete penetration of the Smoke. Smoke immediately backing up into
the blower indicates a line blockage — if this occurs, testing should be discontinued Until the line has been cleared.
Eublic Notifcatian: Proper notification and education of the Public is essential to successful Smoke Testing. This program
should begin well in advance, and continue up to the day of testing in each area. Notification and coordination with all local
emergency departments is also essential. More information on Notification is available.
CAUTION: All smoke, including Superior@i Smoke, can irritate bmathing passages_ Persons with known respiratory sensitivity should not
be exposed to any smoke- Breathing protection is required for exten "heavy exposure, however this should not occur if proper testing
procedures are employed.
Superior Signal Company LLC - 1 -800 -M -TEST o www.SuperiorSignal.com