Checks & Balances

Aquatic Technology Pool & Spa
Paolo Benedetti

Geotechnical reports (soils reports) are required for the proper engineering of all swimming pools, spas, water features, and fountains, not just complex infinity edge, vanishing edge, slot overflow, knife edge, or perimeter overflow pools.

Since I have been in this industry, I have advocated the use of separate geo-technical and structural engineering firms. There is a great value and benefit for the consumer when using separate firms... the separation of "church & state." Simply stated, there becomes a series of checks & balances and peer reviews.

While there are a great many quality firms that provide all of these service under one roof, there is always the fear of inter-office politics wreaking havoc on a project. Since the "check & balance" peer review occurs behind the scenes, the validity and thoroughness cannot be guaranteed. This format does offer some advantages, such as less scheduling delays during the planning & design phases.

However, there is one major drawback... in the event of a catastrophic event or structural failure, a "one-stop shop" will "rally the troops & encircle the wagons" to protect their interests. They will be able to shield themselves from liability by destroying memos & inter-office communications. These documents and dialogues transfer openly between the Designer, Structural Engineer, and Soils Engineer, when separate geo-technical & structural engineering firms are employed.

The geo-technical engineer will initial make minimum recommendations for a foundation design, based upon the sites soil conditions. These recommendations are based upon a few small 4-6" diameter holes drilled randomly in the area of the proposed construction. The resulting report will make generalized conclusions based upon these random samplings, and therefore the report cannot possibly forecast every subterranean condition on the site.

The recommendations which are included in the geo-technical report, are forwarded to the Structural Engineering firm. They will rely more upon the soils analysis (coefficient of friction, load bearing values, expansiveness index, etc.), than the Soils Engineer's minimum structural recommendations.

The reason that the Structural Engineer does not rely much on the Soils Engineer's foundation recommendations, is because the load of the structure, seismic stability, computer modeling & stress analysis, and related calculus had not been performed. Most Soils Engineers do not possess the related education to even come close to making valid recommendations.

For instance if the structure is to be supported on friction caissons (aka: piers) , the Structural Engineer will be the one to calculate the surface area of the caisson. These piers rely upon the skin friction of the surface of the caisson against the earth, to resist movement. The surface area must be adequate to provide enough friction to overcome the loads placed upon them. Oftentimes, the minimum diameter specified by a Soils Engineer, is not of sufficient diameter to create the amount of surface area required to create the proper amount of friction. The "coefficient of friction" of the soil is multiplied by the surface area of the caisson, & the size of the caisson is increased, until the resultant value exceeds what is required. Soils with a high coefficient of friction require smaller caissons, while a low coefficient of friction requires larger & deeper caissons. This is why the Structural Engineer's specifications for the diameter & depth of a caisson design seems "like over-kill," when compared to the Soils Engineer's minimum recommendations.

After the Structural Engineering has been completed, the Geo-Technical Firm is sent a copy of the plans for review. They are looking to ensure that the design exceeds their minimum recommendations, drainage issues are addressed, and that the T's are crossed & the I's dotted. It is an informal type of "peer review." They then issue a letter, stating that they have reviewed the engineering plans and find them to be in compliance with their recommendations. This letter always accompanies the engineering plans, structural calculations, and designers layout & detail plans.

We have lost some projects over the years (good riddance), where the Soils Engineer has reported back to the property owners, "this engineering is over kill. You are going to spend a lot more money than you need to, on something that you will never see." The property owners then rely on ignorant statements like that, to "re-engineer" (dumb-down & degrade) the structural engineering. After all, what does the "pool guy" know?!

The problem is, that Soils Engineer did not fathom the weight of a filled concrete structure or the seismic loads (earthquake, landslide, subterranean water migration, avalanches, tidal surges, etc.) or stresses upon the structure. To make comments like that, when they have not performed computer generate 3-D modeling & stress analysis, mathematical calculations, or even possess a degree in structural engineering, is totally unprofessional, irresponsible & unconscionable.

For a contractor who may have the pleasure of bidding on one of our design projects, such comments should be the clients first cue to "turn & run" & "show the guy the door (with a boot in the backside for good measure)."

During construction, the first inspection will be by the Soils Engineer. When the initial site grading [dirt removal for the future build-up of the pool decks (base rock, concrete, & stone veneer), excavated pool, retaining wall footings & foundations] has been completed, the open holes will be inspected. This is to ensure that the soil conditions are not any worse than the small sample borings. Any changes in the design or structural engineering usually occur at this point, and can result in delays, while the engineering is modified & submitted to the regulating governmental agencies for approval.

Once the project has progressed to the point where the structural reinforcing steel is in place, the Structural Engineer will usually inspect the steel placement. They will look at the grade of steel; diameter of the bars; the steel's placement, spacing, and over-laps; and the clearances to the soil, plumbing, and other objects. This can be a physical on-site inspection if the Engineers are local, if they are remote & the client is willing to pay their travel expenses, or can be done through digital photography & emails.

More frequently, projects are being "virtually-reviewed." Not only does it save everyone time & money, but it provides the Engineer with a record of what occurred. If the Engineer wants to see something from a different angle or close-up, that can be requested. It is important that close-ups of the steel bars, showing the indicating marks for the grade & diameter, also be provided. A "scale" should always be provided in the images for reference - a yard stick, tape measure, or surveyors staff are perfect.

This system of checks & balances ensure that there is an on-going series of peer reviews during the project, until "everything is set in concrete." These inspections occur independently of Deputy (Special) Inspectors & Building Inspections.

The benefit:

The property owner is guaranteed that the contractor is maintaining the project's integrity. Do it right or don't do it!



Paolo Benedetti - Aquatic Artist
"Creating water as art."™
Aquatic Technology Pool & Spa
©www.aquatictechnology.com

What were you thinking?

Aquatic Technology Pool & Spa
Paolo Benedetti

Landscape contractors are not qualified to build swimming pools, let alone complex hillside caisson & grade beam vanishing edge or infinity edge pools.

In the State of California, Landscape Contractors (LC) can now act as an "outdoor general contractor." They can act as the primary contractor with a property owner. when contracting for the construction of a swimming pool, provided that they sub-contract the construction of the swimming pool to a licensed swimming pool contractor. They cannot solely build swimming pools, as any swimming pool contract must be a part of a larger project, for which they are contracting.

After they manage enough project, wherein a swimming pool is a component, they are magically qualified (in the liberal eyes of the great State of California) to take the contractors licensing exam. Though it is merely designed to tests an applicants "entry level" ability, many tout the license as their qualification to build any type of complex swimming pool structure (e.g. hillside pools with drilled caisson or bench stepped foundations).

Case Study:

A landscape contractor (LC) is doing the landscaping, irrigation and lighting on historic California estate, a one-of-a-kind $100,000,000 1920's era property! During one of the many meetings, he hears a comment that the owner desires to rebuild the 1920's era swimming pool. Though they are not licensed to build pools, the LC knows that he can act as the GC for the pool. He sees dollar signs flash across the sky, and offers to the owners "we can do the pool." Hence, the farce begins.

The owner's representative, does his due diligence and discovers that the LC is legally entitled (but not necessarily qualified) to build the swimming pool. The LC locates a locally licensed swimming pool contractor, who agrees to be a "consultant". The LC wants to maintain control of the entire project, and wants the swimming pool contractor to "consult as needed."

The LC locates a local civil engineer to perform the structural engineering. Granted, the structural engineer has never designed a swimming pool before, but hey how hard can a swimming pool be right? Little is he aware, but there are many specialties within his field of engineering, one being swimming pools.

He proceeds to engineer the swimming pool without the assistance of a geo-technical report or investigation. The LC and engineer fail to perform any research regarding the pitfalls of building a swimming pool in close proximity to the ocean. They also neglect to refer to specific California Building Codes (other than those that apply to swimming pools) that apply to structures in high tidal basins, subject to flooding, or near bodies of salt water. They also fail to do any research as to the detrimental effects upon steel, concrete or electrical systems in such close proximity to natural bodies of water.

The project starts off on the wrong foot, when the property owner insists that the project be placed in the exact location as the prior pool. The prior pool failed for reasons, that the LC & engineer failed to even investigate. The project was designed to be an exact replacement of the prior pool, with the addition of a spa, and a new equipment room. They were all designed to mirror the existing structures in appearance. They let the domineering owner dictate what was to occur, without educating them as to the inherent pitfalls. And they failed to offer suggestions to make this project a success.

They started construction by removing the existing swimming pool - but made a critical mistake - they failed to analyze it as it was torn apart. Next, they they drilled into the rock, creating what the engineer called "piers to tie the structure to the bedrock." Epoxy coated reinforcing steel was also cemented into the rock. A concrete box, reinforced with epoxy coated steel was formed & poured to contain the new swimming pool. At this point in construction, a winter storm hits the California Coast.

As it turns out, the existing pool has constantly been subject to severe storms - a few each year. Though on a calm day, the placid Pacific Ocean is 150 feet away, and below some house sized boulders. However, during the few severe winter storms that occur each year, the pool is literally hammered by wind blown waves and tidal surges. The waves actually crash against the cliffs that are behind the pool. Had they merely asked a few questions & looked at some historical images, they would have recognized this.

As they cleared away the storm damage to their form work, removed 2-3' diameter boulders, seaweed and dead fish, they realized that this structure may be subject to future storms. But they failed to take any action.

The project progressed quickly, as the LC's irrigation crews plumbed the pool, utilizing whatever piping was available on their trucks. On any single run, the suction & return lines dangerously vary in size. They are "cosmetically" brought into the equipment room so as to appear marginally adequate. The auto-fill standpipe has so many changes in elevation, that it has a permanent airlock. It simply cannot register changes in the pool or spa water levels.

Another winter storm hits, as the project is nearing completion the following winter. This storm tears out the pool equipment from INSIDE the reinforced concrete building, and carries it out to sea. The cartridge filters and heaters were last seen bobbing out in the Pacific Ocean! Inches of sand, fish, aquatic life and seaweed are cleaned from the shell, AGAIN!

When the masons arrive to install the marble veneer inside the pool, they observe over 50 feet of cracking in the floor area of the shell. When they inquire as to why the pool is already cracking, they are met with a shrug of the shoulders. No investigation is initiated, to determine WHY the shell is cracking BEFORE the pool is even completed.

The LC made a few telephone calls and retains a firm in Mountain View that will inject epoxy into the cracks, sealing them. This firm does not advise the LC that the epoxy is only a filler. They also do not advise that it does nothing to reinforce or stabilize the failing structure... like placing a sunscreen on skin cancer.

The masons begin their work, as the new pool equipment is installed. Shorty after the pool is filled with water, the estate manager observes that the lights in the pool are going on & off, going from bright to dim - though they are turned off! There is some inductive electricity in the pool, causing the filaments to glow. A few weeks later, the pool service technician reports that he feels "tingling" on his aluminum pole as he vacuums the pool.

I am called in to evaluate the project. We determine that the epoxy coated steel and other mistakes, has resulted in a poor bonding grid. The concrete used in the project is cracking & failing. The plumbing on the spa & pool suctions is reduced to such a small diameter & with so many elbows, that the line velocities are exceeding dangerous levels.

It is determined that the spa is loosing water, though a leak detection firm cannot locate any leaks. While examining the progression of construction, I discover that a step was later added to the floor of the spa. But there was a suction grate in that area, prior to the installation of the new step. That warranted further inspection. I discovered that the LC, "extended" the suction line, by placing a curved piece of 3" diameter corrugated drainage pipe into the step, to help extend it to the face of the new step.

Not only is this against every pool construction standard in existence, they failed to seal the original wall where this pipe originated. Water was just seeping through the porous gunite & new step, into the soil below.

Though I have never personally met the owner(s) I know that they are not of significant physical stature (not tall). When I was in the empty spa, I realized that it was almost 6 feet deep! There was absolutely no thought placed into the ergonomic design of this spa. On a project of this magnitude, the spa should have been fitted to the owners physical attributes, jets placed where they wanted them, and "their" custom seats placed to afford them the view that they wanted while in the spa. The air line for the spa venturi's was actually terminated in the rocks behind the spa, so that the owners are subject to the constant sucking sound of a small "shop vacuum" while trying to enjoy the spa.

The marble chosen for the interior of the pool was a significantly soft material and allowed for water to weep through it (marble is not recommended for constantly submerged applications, it decays & is not waterproof - Marble Institute of America).

Major storms still hit this structure, and it has to be drained with a sump pump and shoveled of debris. No provisions were made to vacate this waste water directly to the nearby ocean (a dump line). Nor was there a vacuum port installed for routine maintenance of the pool or spa.

The equipment room is subject to flooding and corrosion of the equipment, boilers, and electrical components. An appendix to the CBC (Calif. Building Code) specifies the methods that must be taken, when structures are built in such close proximity to the ocean & may be subject to flooding. Suffice it to say, the surcharging (impact) from the waves & storms was not considered when this project was engineered. Sealed submarine doors, extended waterproof venting and waterproof electrical systems were omitted (overlooked).

As it turns out, while this pool appeared simple on the surface, it was in fact a very complex project. It required a creative mind and strong personality ...One that could present options and alternatives, to the owners determination to rebuild the structures in the same location. There were creative options, and granted they would have been more expensive, they would have satisfied both the owners desire for an "authentic period reproduction" of the original structures and the need for totally sealed waterproof and submersible buildings.

Everyone involved in this project was involved in litigation. It will literally cost over a couple of million dollars to remove & replace this pool and the related structures. It cost the LC everything he owned - because he thought that "swimming pools are easy to build."

Now, I am sure that he's thinking otherwise.....

and the property owners are wishing they had hired the best design & build firm on the planet!



Paolo Benedetti - Aquatic Artist
"Creating water as art."™
Aquatic Technology Pool & Spa
www.aquatictechnology.com