Archive for the ‘Cost Studies’ Category

N3 Committee’s Review of the Technical Memorandum

February 6, 2013

On August 31, 2012 Sarasota County Staff made a presentation at the South Gate Community Center to explain why grinder pumps were the designated sewer system for the N3 neighborhood.  On December 18, 2012 the County Staff published their Design Technical Memorandum upholding that decision.  The N3 neighborhood committee recently published a critical review of their report.  You will find both documents in the links below; review and compare them and send in your comments.  Please forward these reports to anyone you know that may have expertise in this area.

Review of N3 Tech Memo 2-4-2103

N3 Tech Memo Final 12-18-2012

N3 Committee’s Review of the Technical Memorandum

February 4, 2013

In December of 2012 the Sarasota County engineering staff presented their Design Technical Memorandum for Area N3.  Today your neighborhood committee presented a review of that study to the County Commissioners.  The committee’s review can be viewed thru the link below.  Please look it over and send in your comments.

Review of N3 Tech Memo 2-4-2103

N3 Tech Memo Final 12-18-2012

How much does my grinder pump cost to operate?

February 1, 2013

During last night’s meeting county staff stated “grinder pump electrical cost is about $1.00 a month, or $12 per year”.  Let me offer some background on that statement:

 June 2000

The frequently referenced Hazen&Sawyer/Ayres&Assoc 2000 study (the large binder displayed during the meeting) has this statement on page 45 of Technical Memorandum No.7:

“An annual energy cost of $16 was assumed for each pump based on $0.09 per kilowatt-hour”

These figures are explained to be in 1999 dollars and from sources that include manufacturers representatives.  So, we have operating costs estimated by pump manufacturers offering their products for sale.

That was then, this is now…

With the million grinder pumps that are in use, it hard to believe that no one has used test meters to record the actual power used.  I have not been able to find such data, but I have found estimates that range from $1.35 to over  $5 per month (do a Google search for “power consumption 2 hp grinder pump” and see what you can find).

A major pump manufacturer says the cost is ”typically that of a 40 watt light bulb”, so let’s see how it works out: a 40w light bulb x 24 hours x 365 days = 350 kwh per year.  Our local rate is about $.10 per Kwh, so that’s $35 per year, or just under $3 per month.

A pump motor is a little more difficult to calculate.  Unlike straight resistance loads (like a lightbulb), a motor has a high starting current and a much lower running current.  The 2hp ABS pump has a rating of 10.8 running amps and probably 35 amps starting current.  As the motor starts, it develops a CEMF which reduces the high inrush current and the motor then operates at the lower running amps.  All this really means is that a motor that starts five times a day and runs five minutes per cycle will consume more energy than the same motor that starts once a day and runs for 25 minutes.

An Orenco Systems Engineer calculates that a 1.5 Hp sewage pump operating 20 minutes per day at $0.10 cost per kWh, will cost approximately $3.70 per month.  The SSPMA website estimates $3 to $5 per month, and WERF estimates $44 to $66 per year.  In future conversations and calculations, I’ll use $48 per year (If anyone can find a study where actual usage data was collected, please let me know).

What will your cost be?

Ultimately it comes down to the users: a growing family with children will certainly use more than a retired couple, or a person living alone. So, if a manufacturer says the pump will only cost a dollar a month, it is certainly possible… just like a car dealer could be correct telling you that you’ll get 40 mpg from the car he’s trying to sell.  What do you think?

Area N-3 Sewer Technical Memorandum

January 7, 2013

The County engineering staff has published their Design Technical Memorandum  for the N-3 area sewers.  This report compares the three technologies that were discussed at the August 30 Neighborhood Meeting and describes the current status of the project. The report was presented to the Commissioners on December 19th and will be discussed at the BCC meeting on February 13th.

N-3 Committee needs your help…

This report was sent to your N-3 Committee and is currently being reviewed by committee members.  However, there are no registered Civil Engineers or P.E.’s in the group.  The Committee has asked to have the Technical Memorandum posted here on the blog in hopes that a qualified resident in our neighborhood will come forward and help analyze the report.  Open and read the report below and contact the Committee at n3committee [at] gmail [dot] com if you can help.

N3 Tech Memo Final 12-18-2012


Commissioner Patterson Responds

November 1, 2012

In response to the Oct. 29 post “The Farmington, Ct. Story“, Commissioner Nora Patterson sent me a very thoughtful email and has asked me to share it with you all.  I will summarize her comments.

Commissioner Patterson makes the following points:

  1. The 216 property owners in N-3 get a lot of help from others in paying for our sewers.
  2. There are approximately 15,000 septic tanks being replaced in the PCSSRP.  The cost to us would be much greater if we did not get help from sales tax, state and federal grants, and rate payers.
  3. Residents of N-3 have the option of paying the cost difference to have a vacuum system as opposed to individual grinder pumps.
  4. The County Commission has not ruled out helping our neighborhood.

(read the Commissioners email here – go to 10/31 2:55 PM)

My response to Commissioner Patterson 

Good morning Commissioner Patterson,
Thank you for your thoughtful email.  I do indeed take your comments as helpful.As to my statement that the property owners would ultimately pay whatever cost is incurred, I meant it in the larger sense of all property owners, taxpayers and ratepayers, not just our 216 residents.  Whether the money comes from property tax, penny sales tax, federal or state tax, it comes from a collective “us”.  As individuals there is seldom a direct correlation between taxes paid and benefits received, but there is social benefit for all.  I may choose to use the County Library more than my neighbor and he may use the County beach facilities more than I do.  The overall effect is we live in a nice community and enjoy many tax supported facilities.Of course there is the issue of fairness.  While I can’t speak for the entire neighborhood, I do not expect preferential treatment.  The option of our 216 homeowners paying a cost differential came up at the community meeting ( I believe the term was MSBU).  At that meeting the difference was estimated to be $1.1M.  While reviewing the presentation slides, I found that $120,000 had been omitted from the grinder pump capital cost (Oct. 14 post) and $186,800 was omitted from the O&M cost (Oct. 19 post).  That’s almost a third of the difference for just two items.  I am anticipating that the engineering staff will present a new, comprehensive comparative cost analysis that may well show the systems being close to parity.  Perhaps we can revisit this issue after we review the report.

I sincerely thank you for your interest in our neighborhood:  I received an email from you while you were on vacation, you spent an evening with us at the community meeting, and you are reading the information I publish.  You are obviously giving a lot of consideration to our small community and I, personally, will accept whatever decision you and the other Commissioners ultimately make.

mike s.

Elements of a Life Cycle Cost Study

October 24, 2012

Life Cycle Cost defined

It is “the sum of all recurring and one-time (non-recurring) cost over the full life span of a system. It includes purchase price, installation cost, operating costs, maintenance and upgrade costs, and remaining salvage value at the end of its useful life”.  And here’s what Stantec Consultants’ computerized program includes:  “capital costs, aesthetics, serviceability, inflation rate, interest rate, depreciation rate, operating efficiency and maintenance costs”.  (Whew!)

What do we really need to consider?

The Pareto Principle tells us that 80% of the total cost can be attributed to 20% of the elements of the study.  So let’s look at these two:  estimated Capital Costs and the anticipated O&M.


Capital Costs – This one is really pretty easy.  Using the design drawing, a list of materials is compiled and each item is extended to show the individual material units and quantity required  (If the design shows 216 lots to be served, then the required number of grinder pumps is 216).  Then the labor cost for each material unit is listed.  If there are 216 grinder pumps required with a unit cost of $6000 and a labor cost of $2000, the estimated total for that line item would be (216 x $6000) + (216 x $2000) = $1,728,000. The rest of the material items (pipe, valves, connectors, clean-outs, etc.) are similarly  tallied.  Another item that needs to be included in this category is the individual cost we each incur to run the 220v – 30 amp circuit from our panel to the pump.


Operating and Maintenance Cost – This element of the study is a little more vague, as it requires assumptions rather than straightforward estimates.  An estimate tells us that we need 216 grinder pumps. If, during construction, it is discovered that there are actually 217 homes in our “enclave”, we simply order another pump and the final cost of the project goes up by $8000.  The O&M figures are assumed costs that will occur in the future (here’s where we find the “wiggle room”). These costs are projected out over a given time period and then converted to Present Value.  If there is a bias in favor of a particular system, the costs will be assumed  lower and the resulting PV will be lowerIf there is negative bias, the costs will be assumed higher and the PV will be higher.  This is why an impartial analysis is critical to a meaningful cost study.  I am not suggesting that the upcoming Technical Memorandum will be anything but a totally unbiased report… but sometimes you can’t see the forrest for the trees.

Another component that must be included in this category is the cost to power these pumps.  Cost is cost… it doesn’t matter whose pocket it comes out of, it must be included in the calculations. The homeowner’s cost to power a grinder pump cannot be omitted just because it’s not paid by the county. It’s an expense of a grinder pump system…  and for our N-3 area that expense is $186,800.68 (see Present Value – Oct. 19). 

(to be continued)

Present Value formula

October 19, 2012

I’ll be writing on Elements of a Cost Study next week.  In the meantime here’s something I’ve been thinking about…

When this formula was presented at the Community Meeting I was, well…  perplexed.

I knew I had seen it before, but I really didn’t understand it and I didn’t know why it was being shown to me now.  So I set out to educate myself on PV,  and it’s close relative, FV.  Turns out to be really quite simple:  Present Value (PV) is the amount of money you need today to pay for a series of payments to be made in the future, over a given time period  at an assumed interest rate.   Future Value (FV) is the sum of  a series of payments (investments) over a given time period, also at an assumed interest rate.

This relates to us in N-3 something like this: the additional charge on our FPL bill for a grinder pump will be about $4 per month.  There are 216 of us, so 216 x $4 x 12 months = $10,368 per year.  Let’s use 40 years (instead of 20) for the term and 5% (instead of 7%) as the interest rate.  You can plug it into the PV formula (or use this handy calculator ) and you’ll get $186,800.68 that should be added to the cost of our grinder pump system (the county won’t see it on their bill, but we’ll see it on ours).

Now let’s look at that $48 per year from each of us going instead into a community account for, let’s say, a new community center.  In 40 years the same $10,368 per year at 5% would be (calculator) $1,252,452.06 in Future Value.

I know we’re not going to save up a million dollars for a new community center, but let’s get the county to give us the credit for the $187,000 they’re asking us to pay to power a grinder pump system.

mike s.

Comment from a knowledgeable neighbor:

 “ future value is the amount of money needed at a specific date in the future that is equivalent to an amount of money today” and “everyone should know the value of every additional cost that we need to pay that the vacuum (or gravity) people don’t have to pay”.

Let’s Talk About the Money…

October 18, 2012


The Value of True Life Cycle Cost

I’m going to spend some more time on the topic of cost studies because I think that cost will be the main factor in determining what system we end up with.  As residents of N-3,  I‘m sure that our wants and wishes will be considered, but in the end it will be about the money.  I have gathered a lot of information that I hope will be useful in evaluating the forthcoming Technical Memorandum being prepared by county staff.  Here’s some commentary from Tyler J. Molatore, Systems Engineer, Orenco Systems®, Inc:

“Life cycle costs take all costs into account, which is particularly important for small communities, because communities bear the responsibility of maintaining the system, for the life of the system, after it is installed.  Upfront costs may be misleading because they only represent one part of the overall cost of a system.

The full life cycle cost of a system is based on costs over time, while taking into account the component with the longest life cycle.  We suggest 60 years when communities are comparing the costs of conventional gravity sewers to the costs of other sewer technologies.  Why?  If the life cycle is set at 20 years, the analysis often ignores gravity sewer costs of repairing/replacing lift stations or repairing piping to reduce I&I (infiltration and inflow) at 50 years. (this is precisely the current state of the Goldenrod gravity system) Full life cycle cost analysis avoids unfairly burdening a community’s future generations with unexpected repair costs.”

“Real life data should be used to validate all manufacturers’ claims.  If possible, it’s best to visit, tour, and acquire data from alternative systems that have been operational for several years.Communities that are considering an investment in any sewer technology should diligently seek out other communities with comparable systems and ask about maintenance costs”.

We have many years worth of data from the Englewood area vacuum systems, but  do we have any long-term experience with grinder pumps?  In preparing the Greeley and Hansen 2007 Cape Coral study, David C. Hagan, P.E. sent surveys to several different utilities to get their experience (see pg.53-66).  Maybe we can do something similar.  I also hope that someone will contact the folks in High Springs, Fl. and James City County, Va.  There are very current and very interesting stories in both of those communities (I’ll write about them in the future).

So, What is Life Cycle Cost?

It is the total of all costs of a system over time.  To have real value it has to extend to the useful life of the system.  What is the useful life of a grinder pump system?  Whatever is put in our front yards next year is going to be in place for a long time…  but how long?  Will it be until the pumps have failed a number of times?  How many times?  It’s not just the pumps, it’s the entire system.  Once a system of grinder pumps is installed, they are not going to be pulled out and replaced with a completely new system in 20 years.  From information I have gathered, the benefit a grinder pump’s lower capital cost (if indeed it is lower) starts to be eclipsed by the higher operating cost at about the 15 year mark, so a 20 year projection really doesn’t capture the true cost of the system.  Replacing 5-15% of the pumps annually is expensive, but the real expense comes when the entire tank assembly has to be replaced.  I may not be around when the real expense kicks in, but somebody will!  Hopefully the folks that are deciding for us will look at the all experience that’s out there and make a decision that will be in the best interest of our future generations.

Next: Elements of a Life Cycle Cost Study

What’s the Plan?

October 14, 2012

Let’s see the layout

Before a meaningful cost study can be undertaken, a plan must be developed that shows what we propose to do.  (For our area that means construction drawings similar to those shown below). The progress of a construction drawing is something like this:

  1. preliminary design layout by project engineer
  2. various revisions, final approval for construction
  3. drawing available for bid
  4. incorporating notations from bid, revised drawing is released for construction
  5. working construction drawings – field changes are noted as work progresses
  6. drawings returned to project engineer to verify field changes
  7. changes verified and approved, record drawing is filed as-built

The drawing at stage 3 is used to do a material take-off. This results in a list of items needed for the project. This bill of materials, along with the corresponding installation Labor Units, gives us the labor and materials (L&M) estimates.  From the data sheets presented to us, we see 196 grinder pumps at $6000 each (Low Pressure System line item #12).  A current drawing would show 216 homes, so that would make the estimate for a grinder pump system $120,000 low… for just one line item!  (There are several other discrepancies, but I’m not going to spend a lot of time scrutinizing these sheets…  they’re hard to read and are presumably being completely redone).

What does a construction drawing look like?

Here are a couple of examples:

Archer Engineers, City of La Canada Flintridge, Los Angles, Ca.

Greeley and Hansen, City of Cape Coral, Fl.

As you can see, The Archer Engr. drawing is very detailed, down to individual lot connections.  The Cape Coral Layout is less detailed, but it does show the scope of the project.  I haven’t been able to find any drawings for our area, but hopefully the Technical Memorandum now being prepared will include up to date drawings similar to these.

Final Thoughts on the Community Meeting

October 8, 2012


My understanding from the N-3 Community Meeting is that we are designed for grinder pumps, not for their superior technology, but quite simply because they are cheaper.  We were offered the option of paying the difference for a less problematic vacuum system, so let’s look at the information that was presented to us and see if we can tell what that difference really is.

Annual O&M Cost
Table 4-2 (slide #35) gives the annual Operation & Maintenance Cost for the three systems that were considered.

 (I don’t know why OWTS (Onsite Wastewater Treatment Systems) are shown. The data is from June 2000.  Perhaps they were considered a viable alternative at that time, although at $420 per lot they are more than twice as costly as grinder pumps and more than 8 times the expense of gravity! )

But let’s look at the difference between Grinder Pumps and Vacuum. Recent cost figures I’ve come across indicate that annual grinder pump maintenance is about double the $190 shown.  I’m sure that maintenance cost for vacuum has also increased since 2000, but maybe not at the same rate. For now let’s use the ratio of 2.7 to 1 ($190/$70). In a neighborhood of lot sizes such as ours,  grinder pumps are almost three times more expensive to maintain than a vacuum system.

Future Cost
Going to slide #36 we see a simple table of figures and, at the extreme lower left, a somewhat complex formula.

It appears from the notations that the figures used for O&M were taken from the LOW DENSITY column in Table 4-2, which shows vacuum cost to be double that for MEDIUM DENSITY (that’s us), while grinder pump cost are the same.  This results in a O&M Present Worth cost ratio of 1.3 to 1.  I’m trying to figure how costs that  are almost three times as high annually  work out to be only one third higher after 20 years at 7% interest. ( I tried to work the formula, but I need someone smarter than me to show me how)

Capital Cost
But I’m not sure that any of this is really meaningful. I find the Capital Cost figures of $2.1 M (grinder pumps) and $3.3 M (vacuum) questionable:  the data sheets used to arrive at these figures are incomplete, undated and unattributed.(see slide #33)


Current cost data and a valid Life Cycle Cost Analysis that includes all costs may reveal a completely different picture. The County Commissioners have directed a review and I’m sure that the engineering department will consider all these factors in their forthcoming Technical Memorandum.  Who knows?… a gravity system may even be viable (think “Goldenrod”).