Shallow foundations of a house versus the deep foundations of a skyscraper. A foundation (or, more commonly, base) is the element of an architectural structure which connects it to the ground, and transfers loads from the structure to the ground. Foundations are generally considered either shallow or deep. Foundation engineering is the application of soil mechanics and rock mechanics (Geotechnical engineering) in the design of foundation elements of structures. The simplest foundation, a padstone. Latvian Ethnographic Open Air Museum Buildings and structures have a long history of being built with wood in contact with the ground. Post in ground construction may technically have no foundation. Timber pilings were used on soft or wet ground even below stone or masonry walls. In marine construction and bridge building a crisscross of timbers or steel beams in concrete is called grillage. Perhaps the simplest foundation is the padstone, a single stone which both spreads the weight on the ground and raises the timber off the ground. Staddle stones are a specific type of padstone. Dry stone and stones laid in mortar to build foundations are common in many parts of the world. Dry laid stone foundations may have been painted with mortar after construction. Sometimes the top, visible course of stone is hewn, quarried stones. Besides using mortar, stones can also be put in a gabion. One disadvantage is that if using regular steel rebars, the gabion would last much less long than when using mortar (due to rusting). Using weathering steel rebars could reduce this disadvantage somewhat. Rubble trench foundations are a shallow trench filled with rubble or stones. These foundations extend below the frost line and may have a drain pipe which helps groundwater drain away. They are suitable for soils with a capacity of more than 10 tonnes/m² (2,000 pounds per square foot). Main article: Shallow foundation Play media Shallow foundation construction example Shallow foundations, often called footings, are usually embedded about a metre or so into soil. One common type is the spread footing which consists of strips or pads of concrete (or other materials) which extend below the frost line and transfer the weight from walls and columns to the soil or bedrock. Another common type of shallow foundation is the slab-on-grade foundation where the weight of the structure is transferred to the soil through a concrete slab placed at the surface. Slab-on-grade foundations can be reinforced mat slabs, which range from 25 cm to several meters thick, depending on the size of the building, or post-tensioned slabs, which are typically at least 20 cm for houses, and thicker for heavier structures. Main article: Deep foundation A deep foundation is used to transfer the load of a structure down through the upper weak layer of topsoil to the stronger layer of subsoil below. There are different types of deep footings including impact driven piles, drilled shafts, caissons, helical piles, geo-piers and earth stabilized columns. The naming conventions for different types of footings vary between different engineers. Historically, piles were wood, later steel, reinforced concrete, and pre-tensioned concrete. Main article: Monopile foundation A monopile foundation is a type of deep foundation which uses a single, generally large-diameter, structural element embedded into the earth to support all the loads (weight, wind, etc.) of a large above-surface structure. A large number of monopile foundations have been utilized in recent years for economically constructing fixed-bottom offshore wind farms in shallow-water subsea locations. For example, a single wind farm off the coast of England went online in 2008 with over 100 turbines, each mounted on a 4.74-meter-diameter monopile footing in ocean depths up to 16 metres of water. Inadequate foundations in muddy soils below sea level caused these houses in the Netherlands to subside. Foundations are designed to have an adequate load capacity depending on the type of subsoil supporting the foundation by a geotechnical engineer, and the footing itself may be designed structurally by a structural engineer. The primary design concerns are settlement and bearing capacity. When considering settlement, total settlement and differential settlement is normally considered. Differential settlement is when one part of a foundation settles more than another part. This can cause problems to the structure which the foundation is supporting. Expansive clay soils can also cause problems.
July 13, 2017 update: For the latest, please read “Zebras: Let’s Get In Formation.”A year ago we wrote “Sex & Startups.” The premise was this: The current technology and venture capital structure is broken. It rewards quantity over quality, consumption over creation, quick exits over sustainable growth, and shareholder profit over shared prosperity. It chases after “unicorn” companies bent on “disruption” rather than supporting businesses that repair, cultivate, and connect. After publishing the essay, we heard from hundreds of founders, investors, and advocates who agreed: “We cannot win at this game.”This is an urgent problem. For in this game, far more than money is at stake. When VC firms prize time on site over truth, a lucky few may profit, but civil society suffers. When shareholder return trumps collective well-being, democracy itself is threatened. The reality is that business models breed behavior, and at scale, that behavior can lead to far-reaching, sometimes destructive outcomes.Facebook — the ultimate unicorn — was weaponized to spread fake news during the presidential election. Uber has come under fire for supporting dubious political agendas, tolerating a toxic workplace culture, manipulating employee wages, and circumnavigating regulations. Medium has backpedaled, having realized that while clickbait content may produce the ad-revenue hockey stick investors want to see, it undermines the founders’ original mission to create a publishing model that enlightens, informs, and rewards quality over quantity.Many well-reasoned think pieces* have been written about the gaping chasm between the world we need and the world that exists. Today, we want to provide the seeds of a solution — and to encourage founders, investors, foundations, corporations, and their allies to organize around it.A company’s business model is the first domino in a long chain of consequences. In short: “The business model is the message.” From that business model flows company culture and beliefs, strategies for success, end-user experiences, and, ultimately, the very shape of society.We believe that developing alternative business models to the startup status quo has become a central moral challenge of our time. These alternative models will balance profit and purpose, champion democracy, and put a premium on sharing power and resources. Companies that create a more just and responsible society will hear, help, and heal the customers and communities they serve.Think of our most valuable institutions — journalism, education, healthcare, government, the “third sector” of nonprofits and social enterprises — as houses upon which democracy rests. Unicorn companies are rewarded for disrupting these, for razing them to the ground.Instead, we ought to support companies that provide extreme home makeovers. We can’t assume these companies will be created by accident. We must intentionally build the infrastructure to nurture them.ENTER THE ZEBRAThis new movement demands a new symbol, so we’re claiming an animal of our own: the zebra.Why zebras?To state the obvious: unlike unicorns, zebras are real.Zebra companies are both black and white: they are profitable and improve society. They won’t sacrifice one for the other.Zebras are also mutualistic: by banding together in groups, they protect and preserve one another. Their individual input results in stronger collective output.Zebra companies are built with peerless stamina and capital efficiency, as long as conditions allow them to survive.The capital system is failing society in part because it is failing zebra companies: profitable businesses that solve real, meaningful problems and in the process repair existing social systems.Drawing from the work of many thinkers,** we’ve developed a portrait of what a zebra company is, does, and stands for. This chart outlines how a zebra company compares with its mythical cousin, the unicorn.For a downloadable, printable version, click here.WHY IS IT SO HARD TO BUILD ZEBRA COMPANIES?In the last year we’ve spoken to countless founders, investors, foundations, and thought leaders who believe zebra companies are crucial to our society’s success. Yet zebras struggle for survival because they lack the environment to encourage their birth, let alone to support them through maturity. “I wonder how many change-makers are stuck under the demands of unicorn investors,” said TJ Abood of Access Ventures, who added that he worried about “the opportunity cost to society” under this model.From our conversations with stakeholders, we distilled the most common challenges facing zebra companies:1. The problem isn’t product, it’s process. Tech isn’t a silver bullet. Building more won’t solve the biggest challenges we face today. An app won’t address the homelessness crisis in San Francisco or unite bitterly divided partisan politicians. The obstacle is that we are not investing in the process and time it takes to help institutions adopt, deploy, and measure the success of innovation, apps or otherwise.2. Zebra companies are often started by women and other underrepresented founders. Three percent of venture funding goes to women and less than one percent to people of color. Although women start 30 percent of businesses, they receive only 5 percent of small-business loans and 3 percent of venture capital. Yet when surveyed, women — who perform better overall than founding teams composed exclusively of men — say they are in it for the long haul: to build profitable, sustainable companies.3. You can’t be it if you can’t see it. Look hard outside of Silicon Valley and you’ll find promising zebra companies. But existing and aspiring business owners haven’t seen enough proof that they’ll have a higher chance of becoming financially successful and socially celebrated if they follow sustainable business practices. They lack heroes to emulate, so they default to the “growth at all costs” model. Imagine if every fund allocated a small percentage for zebra experiments. The investing firm Indie.vc has bravely stepped into this space, but it shouldn’t stand alone.4. Zebras are stuck between two outdated paradigms, nonprofit and for-profit. For young companies pursuing both profit and purpose, the existing imperfect structures (hybrid for-profit/nonprofit, Public Benefit Corps, B-Corps, L3Cs) can be prohibitively expensive. The expense comes not only in legal fees, but in the consumption of a founder’s most precious commodity: time. Months are lost searching for aligned, strategic investors who are both familiar and comfortable with alternative models. This presents a chicken-and-egg problem for foundations, philanthropists, and investors alike. They are spooked by unproven alternative models, but companies can’t prove their models work without experiments to fund them in the first place. Moreover, the current tax system doesn’t reward — or even acknowledge — anything other than for-profit (tax) or nonprofit (deduction) strategies. From the IRS’s perspective, there is nothing akin to a “50 percent financial return, 50 percent social impact” investment. This leaves many potential investors in a straitjacket.5. Impact investing’s thesis is detrimentally narrow and risk-averse. Much of the $36 billion in impact investment funding is restricted to verticals like clean technology, microfinance, or global health. This immature market limits innovation in other sectors — like journalism and education — that could desperately use it.“So how will investors turn a profit and mitigate risks?” you may be asking. Dividends? Equity crowdfunding? We don’t have all the answers. But we’ve seen how a company’s business model and values can negatively affect the bottom line (#deleteuber). So what if the opposite is also true? What if more-enlightened dollars invested in more-enlightened companies led to stronger returns? What if companies that stood for something were in fact more profitable? Patagonia, Warby Parker, Zingerman’s, Etsy, Mailchimp, Basecamp, and Kickstarter are a start — but the world needs so much more.MAKE ZEBRAS: JOIN USIf you believe technology and capital must do better, if you are building a zebra company or want to help carve out a space for them to thrive: join usOur goal is to gather zebra founders, philanthropists, investors, thinkers, and advocates to meet in person this year for DazzleCon (November 15–17 in Portland, Oregon)— a group of zebras is called a dazzle! — to learn from one another and pool resources, ideas, and best practices, to collectively advance this set of ambitions. From this gathering, we will capture and share the unique patterns that zebra founders and funders are finding, and we’ll turn a loose network into a powerful, cohesive movement.Are you in? Go here.Jennifer Brandel is the co-founder and CEO of Hearken. Mara Zepeda is the co-founder and CEO of Switchboard. Extra special thanks to Astrid Scholz, founder and CEO of Sphaera.DazzleCon is proudly supported by Knight Foundation, Artha Investing for Impact, Social Capital Markets, Portland Incubator Experiment, and Catalyst Law. Interested in sponsoring? Get in touch.*Thought piece roundup: Anil Dash on Humane Tech, Joe Edelman’s “Nothing to be Done,” Victoria Fram’s “Why An Equity-Only Investment Strategy Overlooks Many Promising Entrepreneurs,” Caterina Fake’s “The Age of the Cockaroach,” Jason Fried’s “Why We Chose Profit,” Christie George’s “Investing in Sharing,” Tristan Harris’s “How Technology Hijacks People’s Minds — from a Magician and Google’s Design Ethicist,” David Heinemeier Hansson’s “Exponential Growth Devours and Corrupts,” Julie Menter’s “On Unicorns: We’re Looking for a Different Kind of Magic,” Tim O’Reilly’s “We’ve Got This Whole Unicorn Thing Wrong,” Andrew Wilkinson’s “Unicorns vs. Horses.”**Jenn Armbrust’s Feminist Business School, Amber Case’s Calm Technology, Jerry Colonna, Ali Schultz and the work of Reboot.io, Anil Dash in conversation with Krista Tippett, in On Being; Seth Godin’s Tribes: We Need You to Lead Us; Jonathan Harris’ Modern Medicine; Ivan Illich’s Deschooling Society; Michael Karlberg’s “Beyond the Culture of Contest”; Jerry Michalski’s “What if we Trusted You?,” Howard Rheingold’s “Toward a Literacy of Cooperation”; Douglas Rushkoff’s Throwing Rocks at the Google Bus; Natasha Dow Schüll’s Addiction by Design; Shel Silverstein’s poem “Zebra Question”; Peter Thiel’s Zero to One; Ari Weinzweig’s Anarchist’s Guide to Building a Better Business series. Zebra companies have been referred to in journalism articles and academic papers, and by some VC firms.Thanks to Jenn Armbrust, Adam Brault, David Chen, Molly deAguiar, John Dimatos, Lennon Day-Reynolds, Corey Ford, Christie George, Seth Godin, Andrew Haeg, Jason Kunesh, Rachel Hankerson, Jonathan Harris, Jennifer Jordan, Luke Kanies, Duncan Malashock, Kanyi Maqubela, Ellen Mayer, Julie Menter, Douglas Rushkoff, Jake Shapiro, Michael Slaby, Rick Turoczy, Stephanie Pereira, April Rinne, Tom Watson. And to Jen McDonald for editing; and to Arthur Jones for the illustrations.
A small submersible AC sump pump with a garden hose connector A sump pump is a pump used to remove water that has accumulated in a water-collecting sump basin, commonly found in the basements of homes. The water may enter via the perimeter drains of a basement waterproofing system, funneling into the basin or because of rain or natural ground water, if the basement is below the water table level. Sump pumps are used where basement flooding happens regularly and to solve dampness where the water table is above the foundation of a home. Sump pumps send water away from a house to any place where it is no longer problematic, such as a municipal storm drain or a dry well. Pumps may discharge to the sanitary sewer in older installations. Once considered acceptable, this practice may now violate the plumbing code or municipal bylaws, because it can overwhelm the municipal sewage treatment system. Municipalities urge homeowners to disconnect and reroute sump pump discharge away from sanitary sewers. Fines may be imposed for noncompliance. Many homeowners have inherited their sump pump configurations and do not realize that the pump discharges into the sewer. Usually hardwired into a home's electrical system, sump pumps may have a battery backup. The home's pressurized water supply powers some pumps, eliminating the need for electricity at the expense of using potable water, potentially making them more expensive to operate than electrical pumps and creating an additional water disposal problem. Since a sump basin may overflow if not constantly pumped, a backup system is important for cases when the main power is out for prolonged periods of time, as during a severe storm. There are generally two types of sump pumps—pedestal and submersible. In the case of the pedestal pump, the motor is mounted above the sump—where it is more easily serviced, but is also more conspicuous. The pump impeller is driven by a long, vertical extension shaft and the impeller is in a scroll housing in the base of the pump. The submersible pump, on the other hand, is entirely mounted inside the sump, and is specially sealed to prevent electrical short circuits. There is debate about which variety of sump pump is better. Pedestal sump pumps usually last longer (25 to 30 years) if they are installed properly and kept free of debris. They are less expensive and easier to remove. Submersible pumps will only last 5 to 15 years. They are more expensive to purchase but can take up debris without clogging. Sump pump systems are also utilized in industrial and commercial applications to control water table-related problems in surface soil. An artesian aquifer or periodic high water table situation can cause the ground to become unstable due to water saturation. As long as the pump functions, the surface soil will remain stable. These sumps are typically ten feet in depth or more; lined with corrugated metal pipe that contains perforations or drain holes throughout. They may include electronic control systems with visual and audible alarms and are usually covered to prevent debris and animals from falling in. Modern sump pump components in the United States are standardized. They consist of: The selection of a sump pump will depend on the application in which it will be used. To select the appropriate sump pump, consider the following: A secondary, typically battery-powered sump pump can operate if the first pump fails. A battery-powered secondary pump requires the following components in parallel with the above others: Alternative sump pump systems can be driven by municipal water pressure. Water-powered sump pumps are similar to backup-battery-driven systems with a separate pump, float and check valves. During installation, the float is mounted in the sump pit above the normal high water mark. Under normal conditions, your main electric powered sump pump will handle all the pumping duties. When water rises higher than normal for any reason, the backup float in the sump is lifted and activates the backup sump pump. As municipal water rushes through the ejector, it creates a powerful suction force which causes the PVC pipe to act like a giant soda straw, drawing water up from the sump and ejecting it outdoors. There are no impellers, turbines, motors, or mechanical parts to wear out. There are no batteries, wires, or chargers to monitor, tend to, or replace. One can also use an ejector pump that uses an ordinary garden hose to supply high-pressure water and another garden hose to carry the water away. Although such ejector pumps waste water and are relatively inefficient, they have the advantage of having no moving parts and offer the utmost in reliability. If the backup sump system is rarely used, a component failure may not be noticed, and the system may fail when needed. Some battery control units test the system periodically and alert on failed electrical components. A simple, battery-powered water alarm can be hung a short distance below the top of the sump to sound an alarm should the water level rise too high. Illustration of a typical pedestal-type sump pump. Sump basins and sump pumps must be maintained. Typical recommendations suggest examining equipment every year. Pumps running frequently due to higher water table, water drainage, or weather conditions should be examined more frequently. Sump pumps, being mechanical devices, will fail eventually, which could lead to a flooded basement and costly repairs. Redundancy in the system (multiple/secondary pumps) can help to avoid problems when maintenance and repairs are needed on the primary system. When examining a sump pump and cleaning it, dirt, gravel, sand, and other debris should be removed to increase efficiency and extend the life of the pump. These obstructions can also decrease the pump's ability to drain the sump, and can allow the sump to overflow. The check valve can also jam from the debris. Examine the discharge line opening, when applicable, to ensure there are no obstructions in the line. Even a partially obstructed discharge line can force a sump pump to work harder and increase its chance of overheating and failure. Float switches are used to automatically turn the sump pump on when water rises to a preset level. Float switches must be clear of any obstructions within the sump. A float guard can be used to prevent the float switch from accidentally resting on the pump housing, and remaining on. As mechanical float switches can wear out, they should be periodically tested by actuating them manually to assure that they continue to move freely and that the switch contacts are opening and closing properly. If left in standing water, pedestal pumps should be manually run from time to time, even if the water in the sump isn't high enough to trip the float switch. This is because these pumps are incapable of removing all the water in a sump and the lower bearing or bushing for the pump impeller shaft tends to remain submerged, making it prone to corrosion and eventually freezing the drive shaft in the bearing. In the alternative, a pedestal pump that is expected to remain idle for an extended time should be removed from the sump and stored out of water, or the sump should be mopped out to bring the level of the remaining water well below the lower shaft bearing.