Saturday, November 22, 2014

Yet Another Combined Sewer Overflow in Atlanta

Yet another big public works project

Fails in less than a year (scroll down a few articles)

As an aside, I note with interest that this spill isn't more broadly reported. Who knows how many of these overflows happen with every storm in Atlanta. 

Targeted rainwater harvesting in the appropriate watershed is the fastest and least expensive method for reducing stormwater surges. Controls can be added to utilize the water before the next rain, or just put a small hole in the tank to release the water over a few days. 

If the release was from overflow, then the 5500 gallon spill could have been prevented for as little as $5000. When is Georgia going to realize that big public works projects are no longer the solution?

Why won't government incentivize property owners to install cisterns? Is it a lack of supporting federal funding? Cronyism? Lack of experience?

Rainwater is a resource, not a problem to be managed. 

Tuesday, October 7, 2014

Where Does Drinking Water Come From?

Take a large body of water

Use solar power to desalinate and purify it.

Transport it using wind energy

And deliver it weekly

This is the where most drinking water comes from. 

Question is: do you want the last miles to be this:

to where it's treated, 

and then pumped through this

Or is it better to pick it up here

put it directly into here

and treat the water as it's used?

Thursday, August 14, 2014

Stormwater Management Costs in Atlanta, Roswell, and Hapeville

We are working on a project for one of these cities. All the stormwater management requirements are about the same for these cities: green roofs, permeable pavement, retention ponds, or rainwater harvesting. The owner wants to redo a driveway, so they were thinking pervious paver bricks. Let's look at a cost comparison vs. rainwater harvesting:

These pavers are the only ones we could find for sale on the internet. They look nice; I might buy them for myself when it's time to replace my driveway. But the owner is concerned about high heels getting stuck in the spaces. And let's compare prices:
1 paver is $28, and covers 32 square INCHES. So you need 4½ to cover a square foot.  That's $125/square foot!

By comparison, an above-ground corrugated steel tank, with the pump and controls necessary to integrate with an irrigation system can be found on the internet for an average of. . .   $1.12/ square foot.

A below-ground steel tank, costs a little more than above-ground, and installation is more. Maybe $3/gallon, installed.

Sure, there's a cost for the space for an above-ground tank. And if you don't already have an irrigation system, you'll need to add that cost. And Home Depot doesn't always have the lowest prices when buying large quantities. But still, $125 vs. $1.12 or $3???

UPDATE:  Received some immediate feedback on this blog entry. Pervious pavers on commercial jobs are available for $8 - 18/square foot. Still, rainwater harvesting is much, much less expensive.

Saturday, July 19, 2014

Inventory Is In!

The first US shipment of Intewa Purain filters is in stock.  We have 4" - 12" Purain rainwater prefilters in stock currently, and 16" is available soon. We have the level indicators also. 

We are looking for reps that want an exclusive market.

Tuesday, May 20, 2014

Stormwater Management Practices - Rainwater Harvesting Is Cheapest By Far

Just finished listening to a presentation of the approved stormwater management techniques approved by the City of Atlanta. Atlanta is requiring that any new construction or remodeling include measures to reduce flooding in the city's creeks and combined sewers.

The costs, according to the presenter:

Green Roof: $20/square foot
Permeable pavement: $14/sf
Bioswale: $7-10/sf*
Rainwater Harvesting:$1/sf

*That's per square foot of permiable space, not per square foot of bioswale.

The rainwater harvesting cost is just the costs associated with reducing the stormwater outflow volume, not using the water. When allocating cost savings, it's best to compare rainwater tank costs with those of other stormwater management practices. Then compare the cost of water treatment and additional piping with the cost of purchasing municipal water for irrigation or other use.

Rainwater harvesting is the least expensive stormwater management technique. And then, it earns a substantial ROI if there is any use for the water.

Wednesday, May 7, 2014

Can Rainwater Harvesting Pay for Itself?

One of the most common questions I hear are wondering whether rainwater harvesting will pay for itself?  The short answer is yes, when engineered with that primary goal, and operated properly.

Why do we need to clarify that ROI is our primary goal? Because when ROI is your primary goal, the following are NOT:
  1. Capturing all, or close to all the rainwater. In many situations, the tanks are sized to collect the first inch of water that hits the roof.  That's fine, but what if we don't NEED that much water? 
  2. Capturing enough rainwater to eliminate potable water used for nonpotable needs, 100% of the time. Or 99%. Or even 95%.  In America, we have an ample supply of water available as backup.  Often, that water is even at the right PRESSURE.
  3. Over treating the water for the application. Either too much treatment, or more treatment capacity (meaning gpm) than necessary.
Looking at the cost for a small system, we'll first look at the most cost-effective uses for rainwater, which is for cooling tower makeup or irrigation. In those two applications typically very little water treatment is required. In the case of cooling tower makeup, it's likely that the water already in the cooling tower is dirtier than the rainwater.

Let's look at the cost for cooling tower make up on a typical building. In the example shown we have a filter that costs about $2000 on the inlet to the tank. The tank itself costs about $20,000 and then the pumping for either irrigation or cooling tower make up about $5000 or $7000. Total: 27,000 for an irrigation system.

The energy cost to pump the water to about 50 psi 6 hours per week for 40 weeks a year comes to about $85 per year at current rates. We estimated a 5 percent energy cost increase per year.

The water saved looking is about 500,000 gallons of water saved per year at a cost of 1.24 cents per gallon comes to about $6200 per year. We projected increases of 8% per year.

This example is based on Northern Virginia where we could find the energy cost, water cost, and impact fees.

Stormwater management fees are calculated differently in different areas. One popular model is to estimate an average amount of impervious surface of a residence, and charge a certain amount for that "block" of impervious surface. Businesses are charged for the number of blocks.  In this example, and another popular method, is to charge based on assessed value. We estimated a $5,000,000 value for the building, and the current charge is 22.441 cents/$1000 assessed value. $1122 per year today, and we estimated an 8% annual increase.

Running through the numbers for this example, we come up with about a 22% annual rate of return, or about 4x the rate of return for the stock market.

Why such an attractive ROI? DURABILITY. These are not light bulbs that fail in 2-3 years. Consider: the WARRANTY on a tank from Georgia Water Tanks is 20 years, including labor. Pumps typically last 10 - 20 years when sized correctly. Controls "never" fail, especially modern controls that have fewer mechanical switches.  We conservatively estimated the total life at 20 years, and included $1000/year in maintenance parts and labor.

To summarize: the most important strategies for cost-effective rainwater harvesting.
  1. Cooling tower makeup and spray irrigation.
  2. Above-ground tank.
  3. Prefilter before tank. No other filtration. 
  4. Full-sized standby water connection, which bypasses the rainwater pump. 
Used effectively, rainwater harvesting with products from GEORGIA WATER TANKS can be a sound financial investment, in addition to helping conserve the world's second-most precious resource. 

Sunday, March 30, 2014

Maximizing Payback

A contractor recently asked me what kind of paybacks we see with rainwater harvesting. Some suppliers say that there is NO payback, and from what I've seen of their product, I would agree! But I'm seeing paybacks as short as 5 years, which is pretty good on equipment with a 20 year WARRANTY. The elements that make for fast payback are:

1. Lots of nonpotable demand. Cooling tower makeup and irrigation are best candidates. How much is the landscaping worth, if there's another total watering ban? In Atlanta, we've had 2 summers in the past 20 years where outside watering was totally banned. Can we assume a 10% annual likelihood in the future?

2. Minimal piping. Locate the tank close to the piping. Stay out from behind walls. Until rainwater is generally approved as a potable water source, we will have to steer clear of using it for toilet flushing when retrofitting. Just too much labor installing a second set of piping.

3. High water costs. Atlanta's are the highest in the country, and are expected to continue to rise at 5-10% per year for the foreseeable future.

4. High impervious surface charges. Atlanta doesn't have these YET, but Gwinnett, Dekalb, East Point, and others do. 

5. High sewage costs. Some areas allow you to eliminate the sewage costs for cooling towers and irrigation, and some don't. Dekalb no longer offers separate irrigation meters. . . they need the money!

6. Use the right equipment. Above ground tanks are now $1-2/ gallon. Below ground tanks can run $4/gallon or more, depending on installation. How much granite is in the ground in Atlanta???

Yaskawa IQ Drives replace control panels. No treatment for cooling tower or irrigation. The submersible well pump in a sleeve design has been replaced with rainwater-specific submersible pumps. Piping to the tank can now go through the base, eliminating the need for heat tracing pipes. 

7. Does the owner value environmental responsibility? The above-ground tanks show customers and employees a conservation mindset. It might translate into more sales or motivated employees. 

Have you evaluated a project and found the payback period to be excessive? Send us the numbers, we love to value engineer.


Friday, March 21, 2014

Rainwater Harvesting at High Schools

Saving the Earth and Saving Money

We have found a few combinations of water supply and demand that are the absolute top when it comes to payback. The common them is:
  1. Ample supply of high quality water. Rooftops are best, especially rooftops made of metal or EPDM.
  2. Significant demand of water that doesn't require much (or any) treatment.
  3. Minimal piping changes.
Here's today's example, a typical high school in the Atlanta area.  On this one, we assumed that:

  1. School is out June and July.
  2. No cooling tower.
  3. We would turn off the irrigation November – March.

The conclusions? 
  1. To store enough rainwater to irrigate 100% with rainwater would require collecting all winter. Over 1,000,000 gallons storage required. Not cost effective.
  2. Using available rainwater for irrigation will reduce total water consumption by approximately 50%, enough to qualify for maximum Potable Water Reduction LEED points.
  3. Toilet flushing is not as cost effective as irrigation. The pumping, treatment, and plumbing are all more expensive.

And the data behind it:

12 Hour Occupants 900  1 Hour Occupants - 900 0
Occupancy Rate 100.00% Building Size (s.f.)                                                                      220,000
Roof Size 120,000 Occupied Hours                                                                                12
Irrigation Area (s.f.) 200,000 GPD Toilets                                                                          2,700
Average RainFall (in) Average Cooling Load Occupancy Days Available Cooling Tower Irrigation  Toilet  Potential Rainwater Storage  Supplemental Water Needed 
Jan 4.2 0.073                 18                   296,856         6,244       48,600                  242,012                    (242,012)
Feb 4.67 0.072                 20                   330,076         6,843       54,000                  269,233                    (269,233)
Mar 4.81 0.121                 22                   339,971       12,650       59,400                  267,921                    (267,921)
Apr 3.36 0.206                 21                   237,485       20,557      496,000       56,700                 (335,772)                     335,772
May 3.67 0.291                 22                   259,396       30,422      496,000       59,400                 (326,427)                     326,427
June 3.95 0.433                   2                   279,186         4,115      496,000         5,400                 (226,329)                     226,329
July 5.27 0.44                   2                   372,484         4,182      496,000         5,400                 (133,098)                     133,098
Aug 3.9 0.44                 15                   275,652       31,363      496,000       40,500                 (292,211)                     292,211
Sept 4.47 0.359                 19                   315,940       32,413      496,000       51,300                 (263,774)                     263,774
Oct 3.41 0.179                 23                   241,019       19,564      496,000       62,100                 (336,645)                     336,645
Nov 4.1 0.151                 20                   289,788       14,351       54,000                  221,437                    (221,437)
Dec 3.9 0.101                 18                   275,652         8,639       48,600                  218,413                    (218,413)
Total:            49.71               202                 3,513,503      191,344   3,472,000      545,400                 (695,241)                     695,241

Thursday, February 27, 2014

8 Rules of Thumb for Rainwater Harvesting for Commercial Buildings in Georgia

For roughing out rainwater jobs:
  1. I recommend a tank size of about 1 gallon/square foot of rooftop if you are using rainwater harvesting as a stormwater management tool. This (slightly) exceeds City of Atlanta requirements, and simplifies the math. 1:1:1 is a good ratio, and easy to remember.

    1 s.f. of rooftop : 1 gallon of storage : 1 s.f. of turf to irrigate.
  2. Not interested in stormwater management, and just want to collect what you need? I recommend sizing a tank on a 1 month dry spell (happens almost every year), and collecting from up to twice as much rooftop as irrigation area.

    3 gallons storage/1 s.f. of turf, collecting from up to 2 s.f/s.f. of turf.
  3. Cooling tower makeup requires 7 gallons/year/square foot of air conditioned office space in Georgia. Also, cooling tower useage alone will use all the rainwater typically collected, for a 7 story building. So if you have a 3-4 story building, you only need to collect from half your rooftop, or you have excess that you can use for irrigation or toilet flushing.
  4. 10 gallons/year/square foot for irrigating turf and other thirsty plants
  5. 3 gallons/person/day for toilet flushing at an office, or 6 gallons/person/day for continuous occupancy.
  6. 50" rain falls/year in Atlanta, about 25 gallons/year/square foot rooftop is usable
  7. Budget Prices: $2/gallon for an above-ground tank is good budget price. This is for a 10,000 - 100,000 gallon tank. That's for tanks, pumps, the extra piping, and the filters needed for irrigation or cooling tower makeup.
  8. $3/gallon for a below-ground tank, pumps, extra piping, and filters for irrigation or cooling tower makeup.

Friday, February 21, 2014

Concerned about water in Georgia?

Georgia's Inaugural Water Summit
Featuring Governor Nathan Deal

February 26, 2014  -  7:30 - 10:30a
The Loudermilk Center Ballroom
40 Courtland Street, NE
Atlanta, Georgia 30303

Hosted by Atlanta Regional Commission and Metro Atlanta Chamber

To RSVP, please click here or contact Sarah Purser at or 404.586.8534.

Thursday, February 13, 2014

Cheaper, Faster, Better

Is that enough reason to consider point-source stormwater management? Fayette County Georgia is considering a tax (they call it a fee) for impervious surfaces.

How about instead of a fee, they offer an incentive, or at least a reduction in the fee, for storing the water and using it? As you'll see in the slides of the Stormwater Management presentation, they offer incentives for residences to put in rain barrels. Why not do the same for commercial buildings? Cost per gallon for commercial is lower than residential. And each project will have a bigger impact.

Another important consideration for stormwater management is how the tank is used. If you want to use the water, i.e. rainwater harvesting, then ideally you keep the tank full.  If your purpose is stormwater management, then the tank needs to be empty before the next rainfall. There is a simple way to do this, and an even simpler way.

Simple Way

Equipment Needed - Tank, Piping, Float Switch, Timer, Pump, Irrigation System

Control Sequence - When the float switch detects water in the tank, wait 48 hours. Then, irrigate until the tank is empty.  It's rain to get a major rain event 2 days in a row. This allows the ground to dry out from the rain, so that it can absorb more water.

You get the added benefit of more water for the plants. You'll also need to mow more often, if you are watering grass. Much better idea would be to water vegetables.

Even Simpler Way

Equipment Needed - Tank. Optional: Piping.

Control Sequence - Drill a hole in the tank, or put an orifice plate in the outlet piping. Calculate the hole size to drain the tank in a day or two. Make a note on your calendar to check the hole for clogs every 6-12 months.

Wednesday, February 12, 2014

Finally Found!

I'm so excited! FINALLY, after 4 years of searching (admittedly, it wasn't a full time search), I think I have found the key to maximizing ROI on most rainwater jobs for commercial buildings!

If attended one of my rainwater presentations in the past, you've remember page like this:

Where I tried to come up with some reasonable estimate of water used for cooling tower makeup (CTMU). It's my assertion that CTMU is one of the best uses for rainwater in commercial buildings, and provides the best payback. It's relatively easy to pipe, even in a retrofit. The rainwater is cleaner than the water in the cooling tower, so treat the water in the tower, not the incoming rainwater.  

But estimating demand correctly is key to maximizing payback.  Too small and you might buy water that you could have stored. Too big, and you bought more tank than you needed (and you dedicated more space than you ought). So trying to realistically estimate demand, I created a table like this:

Assuming a run time based on maximum and minimum average temperatures in a month. It wasn't the best possible estimate, but it was better than anything else I could find. Using these numbers, we came up with a total building demand that looks like this:

Which showed that for buildings 5 - 10 stories and taller, all available water from the rooftop could be used for cooling tower makeup. That's important, because we could use all available rainwater, but not have the extra expense of extra piping to all the fixtures. Just one riser to the cooling tower, which in many buildings is the way it was designed anyway.

Well, I was never happy with the calculation. I knew that there had to be something better. I mean, an outside air temperature equates to a certain cooling load requirement in the building, which after you go through some efficiency losses, equates to a certain amount of water that needs to evaporate (taking the heat with it) in the cooling tower. It's been a long time since I studied that in school.

Well finally!  I've found a resource to calculate the ACTUAL number of gallons of water used in a cooling tower. Not the maximum flow for the size, but how much is required at a given outside temperature. At 70°F outdoors, the cooling tower doesn't have to work nearly as hard as at 100°. First, the chiller doesn't reject as much heat, because the heating load is smaller. Second, the cooling tower is more efficient.  I always knew that there had to be a way to calculate it, but couldn't find the equation. But here it is! Thanks to SPX cooling towers for creating the page.

We also need to calculate the actual cooling load, but that's much simpler. Stay tuned for more reliable payback calculations!

Tuesday, February 11, 2014

Benefits of Above-Ground Tanks

  1. Cost - Above ground tanks cost approximately 40% less than below ground tanks.  Especially in areas of Georgia with rocky soil or high water table, above ground tanks are worth extra consideration. Cost savings are due to:
    a.  Reduced Shipping Costs
    b.  Reduced Material Handling Costs - carried by hand or skid-steer on the jobsite, not a crane.
    c.  Reduced Sitework - pouring a concrete foundation vs. excavating.
  2. Maintenance - With a properly functioning prefilter, neither tank requires much maintenance. Maybe every few years. In the past, both above and below ground tanks required confined space safety procedures. However, access hatches allowing egress through the liners are the next technological breakthrough for these tanks.
  3. Pumping - With positive suction pressure, pumps run smoother and more efficiently. Pumps can be located inside a mechanical room, safe from the environment and eliminating the need to run high voltage electricity outdoors.

Challenges of Above-Ground Tanks

  1. Freeze Protection - The biggest challenge with freeze protection is not the tank itself, but any piping with sitting water. The current generation of tanks solved that problem for the most part, with piping penetrations inside the tank.  The mass of water in the tank will freeze on the surface, but it will not damage the tank. Freeze protection in Georgia can be accomplished with smart recirculation, keeping initial costs low.
  2. Aesthetics - The Great Debate among engineers: are the tanks something to hide or something to show?.  With a tank such as this in full view of passersby and customers, people will certainly know that the business owner is collecting rainwater.  As described inthis Freakanomics article,that might be very desirable indeed.

    By far the most common visual option is unpainted galvanized steel. Epoxy coating and urethane mastic is available.  For a different look, the exterior can be clad in wooden planks to simulate staves, or stone or brick.
  3. Space - The best tactic for maximizing space is to size the tank for the usage, not expected rainfall. This also reduces the cost of the project. ​

Monday, January 27, 2014

Georgia Water *Treatment*???  GWT is now the Georgia industrial representative for Orival filters.  I've used these the past few years as my standard self-cleaning 5-10 micron filter.  For rainwater, we used them for flows from 5 - 150 gpm.  But Orival has standard products up to 24" and 10,000 gpm, with custom manifolds bigger than that.

You can catch a glimpse of one of these in action here:

Sunday, January 19, 2014

The Week Wasn't Over!

The LLC registration allowed me to do all the other stuff that I needed right away.

Bank Account - Since I use Bank of America for personal checking, I signed up for a business account. A little scary that I could transfer all the startup money to the new account, with just a phone call!  

Logo - This was a great process, and I highly recommend Crowdspring.  Here's a link to the project, which will be viewable until mid-February only.  For $300, I had over 100 choices, from dozens of different artists.

Now I need to print business cards before my Monday appointments!

Friday, January 17, 2014

Checked off the list this week:

LLC registration (tip:  Legal Zoom was worthless, and Georgia Secretary of State website VERY easy to use)

Business License - Dekalb County was a pleasure to work with.  Really. Had a little trouble categorizing the business, which surprised me.  How many manufacturer rep firms are there??? According to these guys anyway, the NAICS number is 541613.

The zoning department could have been my biggest obstacle, as there could be a real problem if I were storing the huge tanks in my front yard. Nice to see a little trust, even if they make a note to later check on me.

Liability Insurance - For a small company like mine, shopping the web was easiest.  I definitely recommend using a few of the services, especially if your business doesn't fit a neat category.  GWT is going to be mostly sales, but also a little jobsite labor.

Both the Licensing and the Insurance people want to know "how much are you going to sell this year?"  So do I!  I decided to guess low.  I think that they audit these things after your first year, and adjust next year's bill accordingly.

Thursday, January 9, 2014

Freeze Protection

After this week's cold snap (low was about 7°F), we have seen quite a bit of freeze damage. The concerns with above-ground water tanks include:

  1. Damage to the tank or liner.  Probably only going to happen if the whole tank freezes, as water can expand above or below the waterline.  We would need a full week of temperatures below 20 in order for that to happen.
  2. Damage to pumps or piping when the ice begins to thaw.  This is more likely.
  3. Damage to exterior above-ground piping.  MOST LIKELY.  But we can prevent this the same way we protect any other pipes.  Insulation and heat tape, drain, or bury.
If you have any tips for leak-free installations, please add them in the comments.


Tuesday, January 7, 2014

Hello World!

Back into the rep business.  I've learned so much the past 20 years.  I've seen successful rep companies, and some that weren't.  Big markets and small.  This is going to be fun!