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The other thing we learned was that we need to be far more careful about what goes in the sewer system.  Paper towels, baby wipes and hand towels do not deteriorate in the sewers.  No matter what manufacturers claim, you find them everywhere and they look just like they did when flushed.  They clog lift station pumps and pipelines.  Do not put these down the toilet for any reason?  Likewise there are no feminine hygiene products that should be flushed, ever!  Again regardless what the manufacturers claim, you can find there ubiquitously in the sewer system and they look, well just like they did when flushed.  No biodegradation.  I have included some figures.  They show up in pump clogging and at plants as well.  They are not biodegradable.  Again do not put these down the toilet!  Put all these products in the trashcan in the bathroom.

Worse, do not put grease down the drain.  One photo is a greaseball in a manhole.  It fills the whole manhole up!  Of course the feminine hygiene products, towels, wipes, etc. plus grease make almost impenetrable obstacles that block the sewer system.  So we need to remove the inflow and we need to keep grease and the reset of these products out to reduce the costs of operating the wastewater utility.  We all contribute, and we all can help.  We want systems to operate properly and dependably, so let’s do our part.

photo 3 photo 1 GREASE


Wastewater utilities and water utilities are intrinsically linked.  Wastewater utilities often discharge to water bodies that are water supplies for downstream water plants.  In other cases, wastewater plants provide additional supply options to reduce water demands in the form of reclaimed water.  However as a wastewater utility, costs are often associated with power- pumping and aeration, which can be 30% or more of the utility’s costs in the worst cases.  However, substantial savings in operations can be achieved by reducing the amount of wastewater that must be pumped and treated and in some cases that reduction also is associated with water quality benefits for the reuse of reclaimed water.  Utilities have long dealt with the infiltration and inflow (I and I) issues in their system by televising their pipes and identifying leak points, but this primarily addresses only the infiltration part of I and I.  Inflow and infiltration are not the same thing – they are very different and must be addressed differently.  Inflow causes hydraulic issues during rain events – like sanitary sewer overflows and basement flooding.  Both subject the utility liability from lawsuits and/or regulatory fines.  Inflow is the risk issue that must be addressed to protect the utility.  A cost effective solution to inflow involves low tech, low cost methods can identify the problems that can corrected easily.  Removing the inflow portion from I and I, often leads to a more focused plan for infiltration correction.  What are those tools?  Smoke testing, cleanout repairs, sealing manholes and manhole dishes.  But each of these needs to be carefully selected.  Because these solutions, pipe that leak can be seen through another low tech solution – a midnight monitoring event.  Recent efforts here in south Florida indicate that only 15-20% of the pipes in a sewer system need to be televised and within those, about half the leaky pipes are actually not leaking – they are broke laterals.  Laterals are one of the most ignored parts of the sewer system – often they are small pipes and much of the piping is on private property so the utility does not address those pipes.  And in many utilities these are the pipes in the worst condition.

Other things that our efforts have shown are that new pipe can leak, just like old pipe, clay is not the only pipe that leaks and that the inflow solutions can be very helpful.  Figures 1-4  show how the solutions affected three lift stations and one community.  The graphs show rainfall vs flow.  Before these efforts, the flows increased with rainfall events.  After, they did not.  Hence this utility was able to resolve its risk for overflows at a cost of under $500/manhole.  That is relatively inexpensive.

LS 52 db LS 54 LS 53


I had to share this, from a nonscientific survey of people adamantly opposed to any consideration of changes to our climate:

1. I can’t do anything about it so I don’t care about it
2. People can’t alter what is happening with the earth because it is too big
3. It’s natural, so we can’t do anything about it
4. It’s not an issue now, so it’s somebody else’s future problem
5. The science is inconclusive so why do anything yet. Let’s see what happens
6. Trying to address it will cut jobs
7. We won’t be competitive (i.e our profits will drop)
8. It requires changing our business model (energy)
9. If we talk about it no one will develop in our community
10. Costs too much

I had to post this as many of you will have comments. But before you do, these about this a minute……

The first five are based on no facts, but a desire to ignore the issue entirely. The second five are more poignant because aren’t these pretty much the same arguments to deny the need to correct water pollution concerns in the 1930s? Or 1950s? Or even 1970s? Or even today with hog farms, frack water, acid mine waste, coal dust slurries, etc.? Or actually pretty much every regulation? I seem to recall Tom Delay making this argument when he was in Congress before he was indicted.

Now think about the Clean Water Act, Clean Air Act, Safe Drinking Water Act, and others. These regulations are designed to correct ills of the past that were simply ignored due to the first five arguments above, ignoring the fact that prevention is always less costly than cleanup afterward. To we pass regulations to clean up problems and protect the public health going forward. Otherwise why have a regulation?

So let’s talk about that jobs impact. The reason is that after the passage of these regulations, didn’t the number of professional jobs (like civil and environmental engineers, environmental and other scientists – STEM jobs) increase? Isn’t increasing STEM jobs a priority? So won’t dealing with climate issue perhaps create a similar increase in STEM jobs? Yes, costs for water increased and the cost for the effects of climate changes will cost money, but don’t these challenges create opportunities? Isn’t this akin to dealing with problems with development from the past? Just asking…..


I love stories about sewage in print.  As a water/wastewater guy, it is amusing to see sewer stories in the local papers and national news when they are about the “oddities” of operations.  One recent article talked about the impact of “flushable items” that should not go down the toilet.  “Flushable” wipes was the offender this time, but past discussion involved tampons, diapers and paper towels.  The reality is that NONE of these items should ever go down the toilet.  Those paper toilet seat covers are questionable as well.  Let’s see why. 

Sewer agencies have a very different view of what is flushable that tampon manufacturers, diaper manufacturers, paper towel and now flushable wipe makers.  Sewer agencies are responsible to insure that waste moves down the gravity pipes and through the lift station pumps without creating backups in the system.  The majority of material in a sewer system is water.  Followed by chopped up solids.  The design of the toilet involved two separate concepts.  One is simply creating the opportunity for a syphon to move waste when flushed but holding water when not.  It is a gravity principle based on partial pressures.  Simple stuff.  But toilets also tend to “chop up” material when the flushing action occurs.  The flush is violent and thin toilet paper and the soft solids in the toilet are easily shredded and blended into the water.  Think about your blender.  Soft stuff gets chopped up.  Enough mixing, it is all liquid.  As a result there is very limited opportunity for either thin toilet paper or most solids to plug up a toilet. 

But people don’t like thin toilet paper.  So we have manufactures making toilet paper with cotton fibers in it to make the paper soft.  And people like the “high quality” paper towels that upscale restaurants use.  Unfortunately too many people use those high end paper towels on the toilet seat, so down they go.  Wipes are reinforced paper also.  Fibers make them strong enough to, well wipe.  Tampons are notorious as absorbant fibers.  The key in each case is the fibers.  Fibers are not chopped up during a flush because the toilet flush is not designed to shed cloth.  As a result two things happen.  First, the fibers then to stay together as a mass.  Grease and other materials in the sewer system will stick to eh fibers making an even larger glob of material.  A recent YouTube photos showed a 15 ton grease ball in a large sewer system.  Grease and fiberous materials in the sewer system – you don’t want that to plug up your interceptor.

The other problem is lift stations.  The pumps at lift stations are designed to pass a 2.5 in ball, but not a bunch of strings.  As a result the fibers get stretched out, and wind around the pump impeller rendering it useless.  Or the material may mat in the impeller preventing the pump from pumping water.  One of the most common lift station problems is fiberous material winding around impeller shafts that burn out pumps.  Pumps cost thousands of dollars to repair or replace, so this is money from the ratepayers’ pockets.  One of my clients had the restaurant problem.  The lift station impellers would completely clog every 3 days.  The lift station would nearly overflow before the pumps were removed, the guys would open up the pump, and dig out the material.  Obviously fiberous paper and there were only two connections to the lift station.  The City ended up installing a $160,000 grinder system to grind up this material because the restaurant was unwilling to change their practice.  The major offender was women using the paper towels as seat covers.  The lines inside were a mess as well. 

The moral of the story is that toilet paper, water and body waste goes down the sewer.  Not napkins, feminine hygiene products, baby wipes or any fiberous paper material that feels soft, but won’t deteriorate, regardless what the manufacturer claims on the box.  These material do not degrade, the only create costly repairs, inconvenient and costly backups and a host of other problems for downstream users and the utility.  Put this material in the proper trash can. 

And see where else can you talk about this stuff, except when talking about sewage?


Based on my last blog, his inquiry came to me.  And I think I actually have an answer:  when bakers and insurance companies decide there is real exposure.  Let’s see why it will take these agencies.  There is very little chance, regardless of good faith efforts, significant expertise, or conscientious bureaucrats to stop growth and development.  The lobby is simply too strong and local officials are looking for ways to raise more revenues.  Development is the easiest way to increase your tax base.  As long as there are no limits placed on develop-ability of properties (and I don’t mean like zoning or concurrency), development will continue.  But let’s see how this plays out.  Say you are in an area that is likely to have the street inundated permanently with water as a result of sea level rise (it could be inland groundwater, not just coastal saltwater).  For a time public works infrastructure can deal with the problem, but ultimately the roadways will not be able to be cleared.  Or say you are located on the coast, and repeated storm events have damaged property.  In both cases the insurance companies will do one of three things:  Refuse to insure the property, insure the property (existing) only for replacement value (i.e. you get the value to replace) but no ability to get replacement insurance, or the premiums will be ridiculous.  We partially have this issue in Florida right now.  Citizen’s is the major insurer.  It’s an insurance pool created by the state to deal with the fact that along the coast, you cannot get commercial insurance.  So Citizens steps in.  The state has limited premiums, and while able to meet its obligations, in a catastrophic storm would be underfunded (of course in theory is should have paid out very little since 2006 since no major hurricanes have hit the state, but that’s another story). 

As the risk increases, Citizens and FEMA, the federal insurer, have a decision to make.  Rebuilding where repeated impacts are likely to happen is a poor use of resources and unlikely to continue.  Beaches and barrier islands will be altered as a result.  The need will be to move people out of these areas, so the option above that will be selected will be to pay to replace (move inland or somewhere else).  Then the banks will sit up.  The banks will see that the value of these properties will not increase.  In fact they will decline almost immediately if the insurance agencies say we pay only to relocate.  That means that if the borrowers refuse to pay, the bank may not be able to get its money out of the deal on a resale.  We have seen the impact on banks from the loss of property values as a result of bad loans.  We are unlikely to see banks engage in similar risks in the future and unlikely to see the federal insurers (Fannie Mae, Freddie Mac) or commercial re-insurers like AIG be willing to underwrite these risks.   So where insurance is restricted, borrowing will be limited and borrowing time reduced.  That will have a drastic impact on development.  The question is what local officials will do about it?

There are options to adapt to sea level rise, and both banking and insurance industries will be paying close attention in future years.  Local agencies will need a sea level rise adaptation plan, including policies restricting development, a plan to adapt to changing sea and ground water levels including pumping systems to create soil storage capacity, moving water and sewer systems, abandoning roadways, and the like, and hardening vulnerable treatment plants.  Few local agencies have these plans in place.  Many local officials along the Gulf states refuse to acknowledge the risk.  What does that say about their prospects?  Those who plan ahead will benefit.  Southeast Florid a is one of those regions that is planning, but it is slow process and we are only in the early stages.


Storms highlight the need to reduce infiltration and inflow into the collection system so as not to overwhelm the piping system causing plant damage or sewage overflows into streets, so much of the focus has been on dealing with removal of infiltration and inflow through televising the sewer system and sealing or lining sections where leaks are noted.  However, many miles of videotape show virtually nothing, so significant money is spent to find “nothing.”  Part of this is because “infiltration” and “inflow” are not the same, and storm events do not highlight infiltration nearly as much inflow.

The manholes and clean-outs are required for access and removal of material that may build up in the piping system and for changes in direction of the pipe.  Manholes are traditionally pre-cast concrete or brick, with brick being the method of choice until the 1960s.  Brick manholes suffer from the same problems as vitrified clay sewer lines – the grout is not waterproof so the grout can leak significant amounts of groundwater.  The manhole cover may not seal perfectly, becoming another source of infiltration.  Pre-cast concrete manholes resolve part this problem, but concrete is not impervious either.  While elastomeric or bituminous seals are placed between successive manhole rings, the concrete is still exposed.  Many utilities will require the exterior of the manholes to have a coal-tar or epoxy covering the exterior which helps to keep water out.

Inflow results form a direct connection between the sewer system and the surface.  The removal or accidental breaking of a cleanout, unsealed manhole covers, laterals on private property, connected gutters or storm ponds, damaged chimneys from paving roads, or cracking of the pipe may be a significant source of inflow to the system.  All are potential sources of inflow which can be identified easily during storm events.  The peaking that correlates with the rainfall is inflow, not infiltration since infiltration is part of the base flow that creeps upward with time.  When operators see peaks, this is not indicative of infiltration which is groundwater.  Think inflow.   Inflow causes peaks in run time on lift station pumps, and create potential overflows at the plant.  The good news is that simple, low tech methods can be used to detect inflow, which should be the precursor to any infiltration investigation.

The following outlines a basic program for inflow detection and correction for any utility system.  The order is important, and pursuing all steps will resolve the majority of issues.  The first step is inspection of all sanitary sewer manholes for damage, leakage or other problems, which while seeming obvious, usually surprises.  The manhole inspection should include documentation of condition, GPS location, and some form of numbering if not currently available.  Most manholes have limited condition issues, but where the bench or walls are in poor conditions, that should be repaired with an impregnating resin.

Next is repair/sealing of chimneys in all manholes to reduce inflow from the street during flooding events.  The chimney includes the ring, cement extensions, lift rings, brick or cement used to raise the manhole ring.  Manhole covers are often disturbed during paving or as a result of traffic.  The crack between the ring and cover can leak a lot of water.  The intent of the chimney seal is to prevent inflow from the area beneath the rim of the manhole, but above the cone.

The next step is to put dishes into the manholes.  One might think that only manholes in low lying areas get water into them, but surprisingly every manhole dish that is properly installed has water in it.  Hence assume that all manholes leak water between the rim and cover.  Most collection system workers are familiar with dishes at the bottom of the manhole where they are of limited use.  This is because the dish deforms when filled with water or is knocked in when the cover is flipped.  The solution is a deeper dish with reinforcing ribs.  No ribs, don’t use it.  A gasket is required.

Once the manholes are sealed, smoke testing can identify obvious surface connections.  The normal notifications, inspection and documentation will identify broken or missing cleanout caps, surface breaks on public and private property, connection of gutters to the sewer system, and stormwater connections.  All should be documented via photograph, by associated address and public or private location. The public openings at cleanouts can be corrected immediately.  However, if the cleanout is broken, it may indicate mower or vehicle damage, that can occur again.  If missing, the resident may be using the cleanout to drain the yard.  In either case the collection system needs to be protected.  USSI (http://www.elastaseal.com/about_us.html), located in Venice, FL developed a solution, called the LDL plug to correct those commonly broken or commonly opened cleanouts to reduce inflow.

Notices should then be sent to property owners with documentation of the inflow connections to their property.  This is sometimes the most difficult part of the program due to political will, but it is necessary.  This finishes the inflow correction portion of the project, but one more step will help focus efforts for the second “i”.

The final step is a low flow investigation, which is intended to focus on the infiltration piece of the problem.  Such an event will take several days and must be planned to determine priority manhole to start with and sequencing.

Based on a projected plan and route:

  • Open the manholes
  • Inspecting them for flow
  • Determining if flow is significant.  If investigation of basin will end and new basin will be started.  If flow exists, open consecutive manholes upstream to determine where flow is derived from.  Generally a 2 inch wide bead of water is a limit of “significant” infiltration.

Documentation of all problems and corrections in a report to utility that identifies problem, location and recommended repair.  Identification of sewer system leaks, including those on private property (via location of smoke on private property).

The example in Dania Beach, FL was that the last step indicated that only 15% of the sewer system needed to be televised.  This saved the City almost $1.2 million.  Their total costs is under $1.4 million for all parts of the project, spread over several years and contracts.  Overall the hope is that the inflow and infiltration programs together will save $400,000/yr, a five year payback.  But the key is to insure you get the inflow as well as the infiltration… Otherwise storms will continue to overwhelm plants, creating public health concerns and ruining your reuse program.

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