Utility employee writes on Marco's 'proactive sewer' project

Bart Bradshaw contributes cover story, 'Adding value to sanitary sewers,' for utility magazine

Article Highlights

  • View full story by Bradshaw in related link to the utility magazine
  • View full Weekly Update by Steve Thompson of Oct. 9 in related links
Chairman Bill Trotter shakes hands with Ana Gonzalez, chair for the Florida Section of the American Water Works Association, upon the Marco Island Collections and Distribution Departments reception of a first in state award for quality water service in January 2009. The team includes Bart Bradshaw, Frank Clark, Steven Cunningham, Jean-Claude Dumervil, Michael Ehlen, Brandi Garwood, Cameron Hayson, Tony Horrocks, Michael Lynch, Rodolfo Martinez, Charles McDougall, Fidencio Mireles, Mark Neve, Christopher Nygard, Christian Polanco, Silvestre Rodriguez, Marvin Schroeder and Pablo Uvalle.

Photo by KELLY FARRELL, Staff

Chairman Bill Trotter shakes hands with Ana Gonzalez, chair for the Florida Section of the American Water Works Association, upon the Marco Island Collections and Distribution Departments reception of a first in state award for quality water service in January 2009. The team includes Bart Bradshaw, Frank Clark, Steven Cunningham, Jean-Claude Dumervil, Michael Ehlen, Brandi Garwood, Cameron Hayson, Tony Horrocks, Michael Lynch, Rodolfo Martinez, Charles McDougall, Fidencio Mireles, Mark Neve, Christopher Nygard, Christian Polanco, Silvestre Rodriguez, Marvin Schroeder and Pablo Uvalle.

— Bart Bradshaw, Collections and Distribution Manager for Marco Island Utilities, contributed to the cover story of Utility Infrastructure Management Magazine's article on the three-phase sanitary sewer rehabilitation program being applied on Marco Island. The sewer project was used as an example of proactive wastewater collection system management.

The three phases are condition assessment, rehabilitation design and implementation. Based on the condition assessment, depreciation of the existing sanitary sewer system was predicted over the long-term. This analysis was used to determine the financial benefits of sanitary sewer rehabilitation in addition to preventing failures and reducing infiltration and inflow (I&I), thereby maintaining the desired level of service.

Portions of the cover story written by Bradshaw and V. Firat Sever, a consulting engineer at the Fort Myers office of AECOM Technology Corp. are below. The full article is also in City Manager Steve Thompson's Weekly Update of Oct. 9, in the related links.

Project Scope

The City of Marco Island purchased the water and wastewater utility from a private company in November 2003 and renamed it Marco Island Utilities. As the management became familiar with the utility’s capital needs, the projects were prioritized from most critical to least critical.

At the beginning of the fourth year of ownership, the utility director set aside funds to begin an assessment of the wastewater gravity system that was built between early and late 1960s. The existing central wastewater collection system consists of vitrified clay (VCP), built in the early 60s, and polyvinyl chloride (PVC) pipes, built in late 60s. Only 40 percent of the Island was served by centralized wastewater collection system at the time.

In coordination with the consultant, the city started an assessment/rehabilitation program for its sanitary sewers. The goals of this program were:

- Assess the structural integrity of the pipelines and manholes

- Identify sources of infiltration and inflow into the system

- Develop a capital improvement plan to prioritize and correct defects that are discovered.

Methods used for inspecting the existing system were closed-circuit television (CCTV) survey, visual inspection in field (manholes), and smoke testing of lateral sewers and selected manholes.

Existing System Inventory

Sanitary sewers on Marco Island consist of polyvinyl chloride (PVC) and vitrified clay pipe (VCP), with clay pipes being older than the PVC pipes. PVC pipes did not demonstrate any notable damage except a few discrete holes and cracks due to rock or miscellaneous object penetration.

The majority of the inspected VCP is in sound or moderate condition requiring point repairs or no repair at all in the foreseeable future. Sixteen percent of the existing clay pipes demonstrated extensive damage such as long and deep cracks and fractures in addition to loose/offset joints.

Approximately 40 percent of the existing pipes are made of clay and the remaining 60 percent are PVC.

Vitrified clay is known for its inertness against chemical attack. However, it is more brittle than PVC and tends to generate longitudinal or circumferential cracks due to external loads. In addition, VCP is less flexible than PVC and tends to separate at joints.

Marco Island is a barrier island located on the eastern section of the Gulf of Mexico in southwest Florida.

Marco Island’s groundwater table is on the average of 3 feet to 3.5 feet below the surface and is affected by tidal action. Because of the fluctuating water table and the constant movement of the sandy soil, the nonflexible clays pipes have sustained most of the damage. Additionally, traffic loads and installation deficiencies (e.g., poor bedding and backfill) may have played a significant role on service life of sanitary sewer pipes.

Extensive defects such as cracks, fractures, holes, loose joints on the pipelines and manholes will potentially allow I&I. Infiltration and inflow will increase the total flow rate and cost of wastewater treatment. Moreover, infiltration is a result of defects in the pipelines as well as manholes, which may be indicative of premature failure of the sewer lines that, in turn, may have costly consequences, such as sanitary sewer backups and damage to the road above the collapsed pipe segment.

Sanitary sewer failures also pose environmental hazards by wastewater leaks out of the pipeline (exfiltration).

The cleaning and televising program included the existing sewers, which are distributed over the Island through the northeast, northwest and southwest. These areas were divided into phases to prioritize and coordinate the project. The overall project included approximately 190,000 linear feet of sanitary sewer pipes ranging from 8-inch to 12-inch in diameter and 833 manholes, which serve 34 percent of the island.

Approximately 6 percent of the existing sewers were excluded from the rehabilitation program due to pipes/manholes being new or recent rehabilitation.

Pipelines

Based on the review of the CCTV records, the authors evaluated the condition of the sanitary sewer main pipes, which was indicated using color coded plans. Three levels of deterioration – sound, moderate and poor – were indicated by green, yellow and red.

Condition of the sewer main pipes was highly dependent on the location and material. Accordingly, minor or no damage was noted to the PVC sewers; whereas, the magnitude of damage to the clay pipes ranged from no damage to extensive. The most common types of defect were cracking, fracture and root intrusion (at joints) in clay, and sagging in PVC pipes. Pipe segments that have frequent fractures and cracks will allow infiltration or exfiltration, depending on the water table and the location of the pipe. In addition, structurally unsound pipe segments are prone to a collapse, which may cause sanitary sewer backups and damage to the road above the pipeline.

Based on the condition of the pipelines and flow rates into the system, upsizing any pipe segments was not deemed necessary by the project team; therefore, pipe replacement was not one of the methods included in the project. Cured-in-place-pipe (CIPP) was the method chosen for relining, which is an established method of structural pipeline rehabilitation.

A well installed CIPP with adequate resin will minimize, if not eliminate, the annular space between the host pipe and liner, thus reducing the risk of annular flow that may enter into the system through service lateral connections (after the liner is cut out at service laterals) and cracks/holes in the host pipe.

CCTV records indicated non-structural, localized damages and leaks in some of the sanitary sewers that are otherwise in sound condition. A complete relining of these pipe segments would not be economical; therefore the suggested method for fixing loose joints and circumferential cracks in the pipe segments that are otherwise in sound condition was chemical grout (acrylamide) injection.

Manholes

CCTV inspection survey records did not provide a clear view of the manholes; and therefore, manholes were visually inspected by the project team.

Forty-six percent of the manholes included in the assessment program were included in the inspection (386 of 833). This selection was based on age and location of manholes (i.e. low lying areas such as swales and low elevations). Wet weather flow rates to the Marco Island Wastewater Treatment Plant are significantly higher than that of dry weather; whereas, based on the CCTV records review, it was understood that infiltration into the collection system was not substantial.

Hence, manhole inspection and assessment was aimed at reducing inflow through manholes and enhancing structural integrity of the deteriorated ones. Inspection was conducted using a standard form developed by the project team.

A majority of the manholes had defects on the upper section (i.e. cover, frame and chimney), whereas, some of them underwent corrosion due to hydrogen sulfide exposure, which damaged the cone and wall. Damage to the bench or trough was observed in only a few manholes, and this was mainly due to root intrusion. Like the sanitary sewer pipes, the condition of each manhole was depicted using a color code. Color coding identifies a manhole’s condition at three levels as sound (green), moderate (yellow), and poor (red).

Anticipated Benefits of Rehabilitation

The rehabilitation program is aimed at addressing all of the defects that have had or will have an impact on the operation of the system at the desired level of service, which is essentially minimized infiltration and inflow and risk of failure.

On the other hand, all of the yellow and red sanitary sewer pipes and manholes will be upgraded to green. In addition to minimized operational problems, this will increase the overall value of the wastewater collection system – an important capital asset of the city.

Conditions of the sanitary sewer pipes and manholes were predicted over the long-term if a rehabilitation program was not implemented. This prediction is based on a linear correlation between degradation observed in 40 years to date and the degradation that would occur without rehabilitation in 70 years.

Condition of the pipelines after 40 years (average age of the inspected pipes and manholes, which vary from 35 to 45 years) was broken down in accordance with the material (clay or PVC). Then it was assumed that the pipe degraded from green to yellow or red over this period in constant increments (i.e. linear degradation), which is a much greater value for clay pipes.

To illustrate, the rate at which clay pipes turned yellow from green was 40 percent; whereas, this rate was 3 percent for PVC pipes. It is more than likely that degradation of a sanitary sewer pipe or manhole is not linear over time as deterioration would be expected to occur at an accelerated pace when the pipes and manholes reach their design life.

However, there isn’t sufficient data to create a model for the deterioration of the pipes and manholes in long-term in the case of Marco Island, as the pipes were inspected once after 40 years. The nonlinearity in the condition of pipelines vs. time plot is a result of different rate of degradation between PVC and clay pipes.

All of the clay pipes are expected to sustain, at minimum, minor damage, and degrade to yellow in 40 years. In other words, there would be no green clay pipes in the system after 40 years without rehabilitation. This results in a decline in yellow pipe quantity as yellow clay pipes proceed to degrade and turn red; whereas, available green PVC pipes turn yellow then transition to red at a lower rate than clay pipes.

Anticipated benefits of rehabilitation in monetary terms were analyzed over the long-term (70 years). The value of a green pipe segment was taken equal to a new sanitary sewer pipe, which is based on new construction ongoing on the other parts of the island. The average unit price ($/linear foot for sanitary sewer pipes) for new construction was amplified by 25 percent to account for relatively low quantity and additional cost of replacing the existing pipes (which would include flow bypassing and extra labor).

On the other hand, there is a social cost associated with traffic interruption and nuisance to the public for new construction or open-trench replacement, which is very complex to define in mathematical terms and excluded from the value of a green pipe. A yellow or red pipe segment is the cost of a green pipe segment (per linear foot) less the cost of rehabilitation required to bring these pipes’ condition to green. The cost difference between green and red pipes is much greater for the red pipes that require replacement.

This study assumes that red pipes and manholes will require replacement in 70 years and therefore, they will be of negligible value at the end of this time period without rehabilitation. Accordingly, long-term depreciation of sanitary sewer mains and manholes is shown in Figure 1. It is anticipated that with the foregoing assumptions, the total value of 190,000 linear feet of sanitary sewer pipes and 386 manholes that were evaluated would decrease from $37.0 million to $32.9 million (present value) in 70 years without rehabilitation.

Summary

We anticipate that by implementing the sanitary sewer rehabilitation program, the City of Marco Island will eliminate the risk of failure of its sanitary sewers, reduce I&I and increase the value of an important capital asset. It is also expected that by reducing I&I, rehabilitation of defective sewer pipes will lower the cost of wastewater conveyance and treatment.

The lowest bid received for sanitary sewer main and manhole rehabilitation is approximately 20 percent of the anticipated depreciation without rehabilitation as present value. It should be noted that there will be some deterioration, hence depreciation, after rehabilitation.

However, the extent of deterioration after rehabilitation is extremely difficult to predict, since the rehabilitation techniques are relatively new, and the authors do not have any field data on the rehabilitated systems that have been in service for an extended period of time. On the other hand, deterioration/depreciation is expected to occur at a substantially lower rate than clay pipes based on the excellent performance of polymeric (PVC) pipes that have been in service for approximately 40 years.

The next step of the program is implementing rehabilitation, and then pre/post rehabilitation condition of the sanitary sewer system with data and pictures incorporated into the GIS database (smart maps) of the city.

More frequent inspection/assessment of rehabilitated or as-installed wastewater collection systems is needed to increase accuracy on the rate of deterioration/depreciation of these assets and a better evaluation of economic benefits of trenchless rehabilitation.

V. Firat Sever, Ph.D., P.E., is a consulting engineer at Fort Myers, Fla., office of AECOM Technology Corp. He has five years of industry in addition to two years of research experience in water and wastewater engineering.

Barton D. Bradshaw is the Collections and Distribution Manager for Marco Island Utilities, Marco Island. He has 16 years in the water and wastewater industry and 10 years in the ship building industry as a pipe and structural welder.

© 2009 marconews.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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Comments » 20

dougenman writes:

And just who is going to help pay for this repair and replacement? The folks in the STRP project while the folks on the old system paid nothing into the STRP project.

Fossil writes:

I recall during the campaign for the last election one of the candidates made a presentation entitled: "The Dirty Little Secret". Now the City is revealing it's "dirty little secret". Remember the words "infiltration" and "exfiltration"? When candidate Nylon exposed this "secret", he was attacked by by John Arceri and Marco Island's utility leadership. Marco Island's old sewer has been responsible for contaminating our pristine waterways for many years and because of the number of users (condo and hotel) has likely been far more damaging then the old septic systems. I would like to know what the projected cost of this rehabilitation project is and of course where the money is to come from. As ALL of these pipes and manholes to be rehabilitated belonged to the old system, should the new customers who were FORCED to hook up to the pipe pay for it? The honesty of our city's leadership and their lack of candor when asked about these problems during the campaign highlight their concern for politics over public good. Why did they not just come out and tell us about the hazard we were living in? Why didn't they propose an immediate assessment so that the users could pay for this? Why did they invent some solution to make all Marco Islanders pay for it without revealing their intent? Is that being honest? Is that doing the right thing? Some good questions to ask the next politicos running for public office. We deserve the best. We deserve honest people leading us. Not a bunch of businessmen out to pick our pockets without telling us what they are going to use the money for.

ChuckKiester writes:

Finally, out comes the information that many of us sought knowing that leaks in the old sewer pipes is/has been the largest source of water contamination (except for stormwater runoff) and a problem that should have been addressed long before the city enacted the STRP. I commend Mr. Bradshaw for his article. Unfortunately, proceeding with the STRP and the resulting necessity of enlarging the sewer plant given the state of disrepair of the plant and collection system has put the city of Marco in the red; ergo, higher water/sewer rate increases. Chuck Kiester

jwputnam writes:

This is disgraceful, needless to say. John Arceri owes Butch Neylon a public apology.

For that matter, Issler, Sal, Monte, et al owe Ed Foster and C.A.R.E.S. a very public apology. Remember "Cave Dwellers". Remember the City's expensive lawsuits. Now will you listen, or is it going to be business as usual down at city hall?

EdFoster writes:

I often have said that the city bought a "pig-in-a-poke" and this article proves it. Mr. Harrison told me repeatedly that the city bought the utility after only three days of technical inspection. An "expert" like John Arceri must have known that vitreous clay pipe laid in shifting sand was not going to last 30 years, but did the City, led by their "utility expert" John Arceri, inspect it before buying? No! They waited four years (according to the article) to inspect the pipe and now want to be praised for discovering the leaks? Wow! What Chutzpah! Praised no less for "discovering" what any utility expert with half a brain should have known from the beginning AND REFLECTED THAT IN THE PURCHASE PRICE.

Fossil, the video inspection of the pipes was done after Wilma. It wasn't that expensive and so couldn't have taken that long to complete. I asked repeatedly for the results but, according to Marco's Public Information Officer, Lisa Douglass, the results "weren't available yet." Seems obvious why! John Arceri wasn't going to let Rony release them until after he had hoodwinked the condo dwellers who had "worn out" the sewer into voting as he wished to prevent the likes of Neylon and crew from getting elected to the Council. For Shame!

Ed Foster

MarcoJimbo writes:

OK, so we find out that dilapidated sewers, NOT single family residence septic tanks were polluting our waterways. No problem, we pit the condos against the outnumbered homowners and get them to pay to fix the problem (STRP). Councilman Chuck Kiester opines the real culprit is stormwater runoff, but City staff isn't quite ready for such a leap of faith. They want to see how much they can bleed from the local landscaping industry first (Fertilizer rules). By the time they admit this was just another "red herring" the collection basins and storm drains will be built, and we'll be $ Millions more in debt. If any good comes from this, the Ad-Hoc Utilities Committee will view Public Works Director Rony Joel and his endless list of "criical" projects with a jaundiced eye and see him as nothing more than a shill for the local construction industry.

happy6 writes:

my question to him is what is all the green sludge balls floating in the landmark waterway everyday?

Marconian writes:

who cares what project was done first? new strp or repair of old! All of you would still be complaining...and that's the hard truth!

playballonK writes:

All the fees to rebuild the old rust bucket are thrown in the face of the STRP residents.
Can you say 'Class Action'?

lauralbi1 writes:

Mr. Kiester: Can I quote you ?? Better yet, I will hold on to your blog and publish it during the campaign. You see, I read the same article after reading your blog and could not find anything in the article to support your statement(s).

"Finally, out comes the information that many of us sought knowing that leaks in the old sewer pipes is/has been the largest source of water contamination (except for stormwater runoff) and a problem that should have been addressed long before the city enacted the STRP." Where do you find this in this informative article ?? There is no mention of quantity, extent or significance to the leakage that we all knew existed. There is nothing "new" in this article. It was published as a technical symposium on the subject of Marco's Sewer lines. Anyone who was not aware of these conclusions is living in a dream World. Now Mr. Neylon's claims that 10,000 or 100,000 gallons a day I do not rememeber the exact number but ewither is ridiculous) are leaking from this system are totally fiction and based on faulty assumptions and are ludicrous. Anyone that would expect any apology to Mr. Neylon is again, living in a dream World.

"Unfortunately, proceeding with the STRP and the resulting necessity of enlarging the sewer plant given the state of disrepair of the plant and collection system has put the city of Marco in the red; ergo, higher water/sewer rate increases".

Yes, Mr. Kiester, 62% of thre Island voters chose to finish the STRP against your wishes and logic. It is and was the proper thing to do. And it still is.
Ed Issler

lauralbi1 writes:

This is so funny, it is exactly what I wrote about recently in this paper. Fossil acts like this is a Dirty Little Secret, which it is not and never has been. Mr. Putnam is asking for someone to issue Mr. Neylon an apology when Mr. Neylon spewed ridiculous numbers to instill panic on our citizens. Lucky his tactics did not work.
This is just an article. This is not anything new or unknown. If pipes are 40 years old, they crack and break.

THE FUNNIEST THING ABOUT THIS WHOLE SUBJECT IS THAT THE SAME PRICIPLES HOLD TRUE FOR THESE PIPES AS DO FOR SEPTIC TANKS!!!!!!!!!!!!!!!!!! THE USEFUL LIFE OF A SEPTIC TANK IS ACTUALLY LESS THAN THESE PIPES AND THE FACT IS THAT OUR SEPTIC TANKS ARE LEAKING PROBABLY MORE THAN OUR PIPES.

THAT IS SOMETHING THAT STUDIES SHOW AS A FACT AND MAKES THIS WHOLE ISSUE REALLY FUNNY FOR THOSE THAT WOULD COMPLAIN THE MOST AND OPPOSED THE STRP.

I WILL TALK TO KELLY AND ASK HER IF SHE IS INTERESTED IN WRITING AN ARTICLE ON SEPTIC TANK LONGEVITY AND LEAKAGE AND HAVE HER INTERVIEW SOME EXPERTS IN THE ARTICLE. IF SHE AGREES, THAT SHOULD MAKE FOR FUN READING.

Love to all and keep on writing !!!!
Ed Issler

Fossil writes:

Issler, you dismiss the negatives in the article by simply saying they don't exist. Your logic is flawed. A mind with only 20% capacity can look at the high rises and hotels on Collier Blvd. and glance over their shoulder at the single family housing and see the difference in population capacity. The multi-family population in high season is many times greater then those living in single family homes. The old sewer was built to accomadate the multi-family, commercial and hotel populations not the housing units. All the septic tanks on the island were not thirty years old, many had been replaced. A sewer serving that large a population and that leaks as much as the article states is leaching far more raw sewage into the soil then all the septic tanks on the island could have (assuming they were all leaking). You sir, are either spinning or you have less then 20% ability to comprehend what the article is saying. Common sense tells us that in this case black really is black and not white like you say. Now answer this question: Who is going to pay to rehabilitate these lines? The original folks who benefitted and used the system for 30 plus years or those who were forced to use the new pipe placed in their neighborhoods during the last five years? I thought so.

MarcoJimbo writes:

If, according to Ed Issler vitreous clay (terracotta) sewer pipes outlast my concrete septic tank, he must be smoking the Jenkem the WasteWater Treatment Plant is supplying to anyone willing to be duped. Jenkem- Google it, you probably won't be surprised.

happy6 writes:

issler...you moron...glad to see you still own kelly at the "buzzard"...why can't you take the pennies off your eyes and see the dimes...because you are too s----- and tainted in your own beliefs...please...go away....there is crap floating down the landmark waterway that has never been seen before...never...why don't you call nancy ritchie and get her butt over to the waterway and see for herself?

condoseller writes:

Mr. Issler...where in this article do you find Facts that support your claims?

" claims that 10,000 or 100,000 gallons a day I do not rememeber the exact number but ewither is ridiculous) are leaking from this system are totally fiction and based on faulty assumptions and are ludicrous. "

The article doesn't provide any estimate on how much sewerage is leaking from these pipes. I hope Kelly ignores your request for another article on septic tanks and sticks to this story. It would be far more interesting and revealing to hear how much sewerage the authors of this article believe is leaking from the pipes. I'm sure there has been a measurement or professional assumptions made during this study.

More too, needs to be revealed about the deteriration of manholes caused by hydrogen sulfide exposure...is this from the dewatering process?

Let's hope the Eagle does some good investigation and writing around these questions so we can get the facts. It is, afterall, the newspapers role to investigate studies of this nature and report the facts.

jwputnam writes:

You know, I remember when a female friend of Sal's stood up at an election "debate" and shouted at Roger Hall (I think): "Can you guarantee that septic systems will not poison the waters of Marco for our children and grandchildren!" It was such a mindless, rehearsed comment from a seemingly uneducated woman that I remember thinking how she probably voted for Al Gore as well. A year or two later, we see the result of similar thinking. Arceri should be very proud of his ability to stir and frighten the masses. Unfortunately, we are paying a big price...and it is going to multiply several times soon.

lauralbi1 writes:

Just so we all know, the blog below was a follow up to a guest commentary written by Bill McMullan. Unless there are 2 (two) Fossils, which I doubt, we can all see that Mr. McMullan is, in fact, Fossil. The fact that anyone would hide behind a psuedonym is unforgivable and cowardice.
You can all confirm who wrote this blog. Just click on Fossil (above) and find this date and time. Then read the subject Guest Commentary.
Now that we have confirmed that Mr. McMullan is Fossil, we can really start having some historical fun. More importantly, we can all discuss that history and put his comments into perspective and relativity.
Ed Issler

March 7, 2009
8:09 a.m.
Suggest removal
Reply to this post
Written on Guest Commentary: Electric Municipalization - The answers and the real questions:
deltarome: The only point I was trying to make is that every subscriber of LCEC has preconceived notions or attitudes about the service and cost of this utility. Attitudes that favors one way of feeling or acting over any other is bias. Attitudes are the result of personal learned experiences that individuals relate to. The world is not run on "facts" alone. It is run by people. People relate to their learned personal experiences or attitudes to make decisions. Just how would Mr. Gibson erase those attitudes or bias from the member's mind? Cannot be done.

jwputnam writes:

Condoseller says it all for me. I sent his comment on to Kelly for perusal. I hope that she takes his good advice. It will be interesting to see.

Fossil writes:

Issler, you are wrong again. I really am Fossil. Instead of trying to figure me out, why don't you simply respond to my questions? Don't try and pin what I write on McMullan. Fossil is my name and I take no credit from Mr. McMullan who obviously is someone you fear very much.

jwputnam writes:

"The truth shall set you free"

http://marcoislandblog.blogspot.com

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