Friday, May 29, 2009
There is more than one theory of climate change and I certainly do not know the true importance of the factors that can impact global temperature change, but I am unwilling to dismiss any theory or area of investigation at this stage. The world is not black and white and our knowledge of the interlacing systems that make up the ecosystems of the earth is truly limited. The visions of the future are not cut and dried. The real world is the one that is subtly interconnected where we have limited knowledge and resources and we need to evaluate the best use of our resources, financial, intellectual, natural, and emotional.
Many greenhouse gases occur naturally in the atmosphere and are also produced by man’s activities, such as carbon dioxide, methane, water vapor, and nitrous oxide, while others are entirely synthetic. Those that are synthetic, man-made include the chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs) and Perfluorocarbons (PFCs), as well as sulfur hexafluoride (SF6). Atmospheric concentrations of both the natural and man-made gases are reported to have been rising over the last few centuries. With increasing global population and technology our reliance on fossil fuels (such as coal, oil and natural gas) has increased, so emissions of greenhouse gases have risen. While gases such as carbon dioxide occur naturally in the atmosphere, man’s activities through burning forest lands, or mining and burning coal, we moved carbon from solid storage to its gaseous state, increasing atmospheric concentrations.
Carbon dioxide levels fluctuate throughout the year, but appear to be consistently rising. From 1970 to 2000, the concentration rose by about 1.5 ppm each year, but since 2000 it has risen to an average 2.1ppm. (ppm is a part per million, a percentage is a part per hundred) These changes are believed to threaten the global environmental equilibrium. According to the National Climate Data Center at NOAA CO2 levels have increased from 280 parts per million in 1850 to 385 parts per million today. According to data from the US Department of Energy, and National Climate Data Center, the carbon in the atmosphere has increased 24% since pre-industrial times but only about 4% of that increase was attributed to human activity. Though this sounds incredibly small, many believe that this small percentage is the tipping point for the carbon cycle and the cause of global warming, the increase in the average temperature that was recorded during the past century.
Water Vapor is the most abundant greenhouse gas in the atmosphere accounting for 94%. It is believed by many that the small change in CO2 emissions due to man causes large changes in water vapor concentrations due to a climate feedback cycle. As the temperature of the atmosphere rises, more water is evaporated from surface sources. Because the air is warmer, it is able to 'hold' more water leading to more water vapor in the atmosphere. As a greenhouse gas, the higher concentration of water vapor is then able to absorb more thermal IR energy radiated from the Earth, thus further warming the atmosphere. The warmer atmosphere can then hold more water vapor and so on and so forth. The proposals to reduce greenhouse gases are intended to move the ecological cycle back from the tipping point.
The best measurements of global air temperatures come from our weather satellites, and they reportedly show fluctuations, but no overall change in air temperature since 1999. (Though record warm and cold years have been recorded since that time the average seems to be the same.) The leveling off of global warming as measured by air temperature while CO2 levels continue to increase is heralded by the school of thought, which says that the sun drives climate changes more emphatically than greenhouse gases do.
Solar cosmic rays intensity and frequency affect the production rate of radiocarbon, C14, the substance that is used by archaeologists to date objects. The original C14 content is due to the amount present in the air at the time of death or encapsulation. The atoms gradually decay back to nitrogen and thus provide a method for dating materials. It was discovered in 1958 by Hessel de Vries of Gronigen that the rate of C14 production varies. Measurements in well-dated annual rings of growth in ancient trees were the key to identifying this. The C14 variations allowed the variation in the solar production of cosmic rays to be measured. Roger Bray of the New Zealand Department of Scientific and Industrial Research then Jack Eddy of High Altitude Observatory in Colorado documented the correlation of solar cosmic rays and the earth’s climate changes.
After becoming much more active during the 20th century, the sun now stands at a high but roughly level state of activity. Solar physicists warn of possible global cooling, if solar activity falls. The earth is such a complicated system with so many inputs and dependent cycles that an accurate model has not been developed and is unlikely to be developed to test these theories. If something as relatively simple as the world economy could not be adequately modeled and controlled to predict and prevent a global recession, how is the more complicated system of earth to be simplified and controlled?
Wednesday, May 27, 2009
Starting next month (July 1, 2009) Loudoun County, Virginia will be requiring all non- traditional septic systems, which were permitted before November 2, 2008 to be inspected annually. Non-traditional systems approved after November 2, 2008 will require annual inspection and an annual maintenance contract. This regulation should ensure that non-traditional septic systems are appropriately maintained and operated in their county. These non-traditional septic systems include: aerobic tank or ATU’s, peat filter systems, single and recirculation sand filters, mound, drip dispersal, spray and low pressure dispersal. Manufacturers of these systems include but are not limited to: Advantex, Aquarobic, Puraflo, Eco-Flo, Whitewater, FAST, BEST, American Drip, and Geoflo.
Though the three chamber system also known as aerobic tank or ATU system is becoming the most popular alternative type system, it is also the most sensitive to improper use and maintenance. They are great when they work, but you need to baby them. These systems were discussed in a previous post. The other non-traditional systems are essentially other methods of replacing a traditional leach field with other filtering methods.
The peat media filter system is a traditional septic tank with peat filtration system instead of a leach field. The filtration system is the aerobic portion of the treatment and is located in tanks which are filled with peat moss. The water is evenly spread over the peat moss then seeps through the media and has a place to collect at the bottom. The peat is an excellent media for allowing the natural secondary treatment of the sewage waste to take place: Absorption and filtration of any impurities chemical adsorption, and microbial assimilation. As a result, these systems are typically capable of removing 90% or more of the polluted mater (characterized as BOD, SS, Coli forms and E. Coli). The life of these systems are 15 years or less until the media is exhausted and needs to be replaced.
Sand filters are a type of aerobic treatment system these are less effective treatments than a peat medium system removing only around 70% of the polluted matter, but that is usually enough in the instances where they are used. These systems date back to the last century and were generally installed above ground to solve a problem with a failing septic. There are single pass sand filters and multi pass re-circulating sand filters. Both types of sand filter are built in a watertight container. Though these systems could be excavated and buried, but they are usually visible and above ground. In addition to physically filtering the water, they perform as a biological filter. A Mound is another form of above ground filtration system. The mound is used as an intermittent sand filter to treat waste water and to disperse effluent through the natural soil. These kind of filtration systems are usually very visible and can be very unsightly.
The basic principles for drip distribution are the same as for other soil-based treatment systems: filtering and bacterial decomposition of waste. The difference is that a drip distribution system distributes the effluent evenly over a large area. A drip distribution system has four main parts: a pretreatment device, a pump tank, a filtering/flushing device, and the distribution system.
I will watch with interest as the Loudoun County program is rolled out. The one area where the county did not think out the implications of their program was requiring all existing system inspections to take place between May 1 and June 30th annually. They need to spread these inspections throughout the year. Their program could serve as a model and test for the new Commonwealth of Virginia regulations required under § 32.1-164 of the Code of Virginia. Loudoun County’s proactive stance could serve the rest of the state in working out all the roadblocks and hurdles for the proper functioning of the regulatory scheme.
Monday, May 25, 2009
This spring I used the WaterCheck with Pesticides to test my water quality. This is a test kit you can either buy and take the sample yourself and ship it off to the laboratory in Michigan or you can have a local laboratory do the sampling to ensure that the local laboratory does a same day analysis for Bacteria (presence/absence for coliform and E.coli) and nitrates. My confidence in the results of the bacterial tests for a sample shipped next day on ice was limited so I went with my local laboratory. The kits are made by National Testing Labs and can be purchased directly from them or from a variety of distributors. A sample report can be seen at this link.
This is an informational test packages targeted to be an affordable option for consumers. It is easy to read with the simple four symbols of green check, blue dot, yellow triangle and red cross. If your entire report is green and blue there is nothing to worry about. If any yellow or red symbols appear, you want to gather more information starting with your department of health and the Laboratory that performed the analysis. Additional testing might be necessary. The WaterCheck with Pesticide covers total Coliform and E.Coli bacteria, 15 heavy metals, 5 inorganic chemicals, 5 physical factors, 4 trihalo methanes, 43 volatile organic chemicals (solvents), and 20 pesticides, herbicides and PCB’s. The Minimum Detection Levels, which are the lowest levels at which the laboratory detects that contaminant with an acceptable degree of accuracy are below the levels established by the Safe Drinking Water Act, but in many instances higher than those required for a compliance test. These tests are designed to give an overall picture of water quality, but do not cover all contaminants that are regulated by the EPA under the Safe Drinking Water Act and are not admissible as evidence in court, which I hope never to need. I believe most people will find that their drinking water source has not been impacted, nonetherless; you should check.
Friday, May 22, 2009
The Congressional Budget Office analysis estimated that price increases associated with a 15% cut in carbon dioxide emissions would cost the average U.S. household $1,600.00 a year. This weekend the World Business Summit on Climate Change will meet in Copenhagen. Bjorn Lomborg, in his opinion piece in the WSJ discusses the cost of green jobs in Spain as well as his opinion of the "Climate-Industrial Complex." (A lovely turn of phrase.) It is difficult to determine the cost benefit analysis of ACES since the exact relationship of man made greenhouse gas reduction and climate change is not known. It is evident, however; that reducing greenhouse gas emissions or any other custodial care of our planet takes resources: money, time, energy and passion. Spend to care for the earth and its atmosphere and there will be less for other things. We as a whole will be poorer, but hopefully with a more sustainable earth. We need to spend wisely to get the most effect from our resources and efforts.
A cap and trade system will cost the American consumer more for power, transportation and many goods. There will be profits to be made in a cap and trade system, who will hold the profits and who will bear the costs remains to be seen. Hopefully, the unintended consequences will not overwhelm the goals of the bill.
I do see the first glimmers of green jobs. This month in CEP (Chemical Engineering Progress) was a very helpful and inspiring article by Jeffrey H. Siegell titled "Improve Your Air Emissions Estimates." With the apparent goal to properly estimate the baseline, Mr. Siegell identified several problem areas in typical reporting estimates. I love system mass balance, waste stream sampling, release modeling-all of it. Though I have not modeled a processing plant since my US EPA and DuPont days, I think there will be great opportunities in systems emissions modeling.
Wednesday, May 20, 2009
A drinking water well that is contaminated could significantly impact your health and the value of your property. There is no requirement, but as one of the 15% of American families whose drinking water is supplied by a private well, I feel I should test my drinking water for these primary and secondary contaminants of concern to the US EPA. In this we need to serve as our own watch dogs. Part of the price of your own water supply is maintaining it and testing it. City and county health departments have local rules and regulations for the installation of wells and can often help with testing for bacteria and nitrates which are contaminants from septic systems, drain fields and livestock. The water well test that was performed when you bought your house probably only tested for bacteria and nitrates. Are you certain that the water you drink is safe?
Due to its protected location underground, most groundwater is naturally clean and free from pollution. However, not all groundwater is clean and safe because we as an industrial society have buried and poured out too much waste. The excellent case studies by Rosemary Stephen “Trichloroethylene (TCE) Water Contamination” illustrates this point better than I could here. For twenty or thirty years homeowners in Sterling, Virginia were drinking water contaminated with TCE and its biodegradation products. According to Ms Stephen “In 1988, Loudoun County Department of Health and the EPA started studies on the land fill, testing for hazardous substances. In three residential wells located close to the landfill, they found traces of TCE, its biodegradation products and pesticides. In 2005, Loudoun County Health Department carried out testing on 68 more wells in the area of the landfill. Forty-five wells tested positive for TCE; 17 of these wells contained concentrations of TCE above the maximum contaminant level (MCL) of 5 micrograms per liter (mcg/L) while 28 other wells contained TCE, but below the MCL.” The site was declared a CERCLA (Superfund) site in 2008. Between 1988 and 2005 no testing was done on the individual homeowner wells. The water was consumed by the young and old.
Have you tested your drinking water this year and if so what have you tested it for?
Monday, May 18, 2009
Groundwater is water that fills the cracks and pores of rocks and sediments that lie beneath the surface of the earth saturating those materials. Gravel, sand, sandstone, or fractured rock have large connected spaces that allows water to flow through them allowing an aquifer to form. Impervious layers of clay and bedrock prevent ground water moving from one space to another. Usable aquifers are bound by impermeable layers; however, if the groundwater is isolated and prevented from flowing the groundwater is said to be perched and is unusable.
Groundwater is ubiquitous and like all water on earth it comes from precipitation that percolates through the soil until it reaches the zone of saturation. Though groundwater is everywhere the quantity and usability of groundwater varies from location to location based on geology and precipitation. Due to its protected location underground, most groundwater is naturally clean and free from pollution. Not understanding the nature of groundwater we have abused it. In the past when we buried things in the earth, fuel tanks, industrial and household waste at landfills, poured solvents out into the dirt, used excessive amounts of fertilizer, had uncontrolled waste from animal feedlots we were contributing to the contamination of groundwater. Homeowner disposal of chemicals, treating a home for termites, excessive use of fertilizers (even organic), and malfunctioning septic systems can all impact onsite groundwater quality and potentially down gradient sites.
Friday, May 15, 2009
According to the US EPA: "Ground water is an important natural resource. More than 50 percent of the people in the United States, including almost everyone who lives in rural areas, use ground water for drinking and other household uses. Ground water is also used in some way by about 75 percent of cities and by many factories. The largest use of ground water is to irrigate crops. We can run out of ground water if more water is discharged than recharged. For example, during periods of dry weather, recharge to the aquifers decreases. If too much ground water is pumped during these times, the water table may fall and wells may go dry.” Wells going dry is what some Californians are worried about. Compliance with the request for water monitoring in California has been limited. Regulation of the water use, charging for private well pumping is something the farmers and rural residents fear.
Americans do not appreciate the true value of clean, potable, on demand water. We take for granted its unlimited availability and overlook the interconnected nature of our water supplies. There are those who think only in the short term, those who do not appreciate the experience of the past, and those who think the past is a perfect predictor of the future. Like 15% of all Americans my water is supplied from a well on my land. All my water comes from groundwater. One of the selection criteria for this house was the water and its quality. Many of the decisions I make on how I live are about protecting my water and the watershed and river in the woods behind my yard. Who owns the water and has rights to it is an interesting question. Ideally, all property owners would see themselves as the custodians of the land resources that they are. We need to think beyond carbon footprint, to understand that all the resources of the earth are limited in some way. Air and water are critical elements of life. Water rights are tied not only to the land but to life.
1. First identify the manufacturer and find a septic maintenance firm certified by the manufacturer. E-mail or call the customer service department to get a list of names. Not all state health departments keep lists of certified maintenance companies. A note of caution, companies that are certified to install may not have the skills to inspect or maintain.
2. Have the system inspected and tested.
There are certain things to note when testing an alternative septic system, which have more than one tank or at least a multi compartment tank.
1. First, the air compressor for the aerobic tank should be running constantly and making a nice humming sound. The condition of the pump(s) and compressor should be assessed.
2. The alarm test buttons should work. (Make sure that the alarm switch is in the sound mode, a bulb can burn out if the alarm is silenced and the system is left with the alarm light on for months.) The alarms should be tested. Trip the alarm by lifting the water level gauge in the second or third tank which is much less disgusting than opening the first tank, but for a full test of the system all the alarms should be tripped.
3. The condition of the tanks should be assessed.
4. The absorption field should be inspected and the valves should be tested one at a time by over riding the timer on the zoner. Tufts of lush green grass around the valves during dry weather could indicate a broken valve or other system leak.
5. Finally, to truly test the system remove some water from the zoner/diverter valve by loosening the top to the valve and letting water flow out for a few seconds and place in a jar and test for bacteria and nitrogen. (Make sure the gasket is properly seated when reattaching the top.) An alternative system should have removed at least 90% of the nitrogen and bacterial load at that point.
It is to be noted that the system takes a period of time to establish the appropriate bacteria levels and achieve operational equilibrium. A house that has been vacant with the water and power turned off can not be properly tested for effectiveness of treatment. It takes a few weeks of use to the system to reach equilibrium. The properly operating effectiveness of the tank treatment system and the ability to track the functioning of the system is the beauty of alternative systems. However, the systems need to be maintained and monitored constantly.
Wednesday, May 13, 2009
When buying a home there are really no simple and sure method of determining if the traditional septic system and leach field are functioning properly. There are signs and indications that a septic system has problems and has failed, but there is not easy way to determine that a traditional septic system is functioning properly. The Septic System Loading and Dye Tests required for some types of mortgages, involves flushing a special florescent dye down a toilet or other drain combined with a known quantity of water sufficient to put a working load on the leach field. If waste water leaks to the ground surface there is a serious septic failure. Depending on various design features, soil conditions and system use, this test can take from 30 minutes to several days. A failed system that has just been pumped or a system that has not been used for a period of time may “pass” the dye test, while the septic system has already failed.
Many septic service companies will perform the service for free or at a minimal expense because it brings in a lot of business. This first thing is to obtain the as built diagram from the health department to identify the type of system, the age of the system and locate the leach/absorption field. The leach/absorption field has sometimes been located in some fairly surprising places.
Septic system failure is unpleasant, unsanitary, could be a source of serious disease and cost thousands to tens of thousands of dollars to resolve. Yet, most homeowners wait until a system fails to take action. The functional lifetime of a traditional septic system is limited. The system is designed so that with proper maintenance it will last 20 to 30 years, under the best conditions. Many other factors can cause early failure of a septic system. Pipes blocked by roots, soils saturated by storm water, compacting of the drain field by parking vehicles or heavy objects on the top of the field, improper location, poor original design or poor installation can all lead to major problems.
It is more likely that these systems fail because they are abused, improperly maintained or just old. Remember that the entire functioning of a traditional septic system is based on natural ecological cycles. It needs to be treated kindly and kept in balance. When a system is poorly maintained and not pumped out on a regular basis, sludge (solid material) builds up inside the septic tank, and then flows into the leach (absorption) field, clogging it beyond repair. Excessive load from toilets and garbage disposal, putting grease, coffee grinds, kitty litter down the drain will shorten the life of and potentially overload the system. Even with proper use and maintenance the system will wear out. Eventually, the soil around the leach field becomes clogged with organic material, forcing sewage upward into the yard or back into the house. Before that happens, however, there are warnings signs. It may be difficult to identify many of these signs without living or spending time in the house.
Signs that a Septic System is Failing:
1. Sewage backup in your drains or toilets. This is often seen as an unpleasant smelling black liquid.
2. Slow flushing of all or most of your toilets. Many of the drains in your house will drain much slower than usual, despite the use of plungers or drain cleaning products (which by the way should not be used with a septic system). Unfortunately, this is often gradual and goes unnoticed.
3. Liquid seeping along the surface of the ground in the back yard near the leach field. It may or may not have a noticeable odor associated with it. Lush green grass growing over the absorption field, even during dry weather or visual stripes in the grass texture and quality is often an indication that an excessive amount of liquid from your system is moving up through the soil, instead of downward, as it should. While some upward movement of liquid from the leach field is expected, too much could indicate major problems.
4. The presence of nitrates or bacteria in the drinking water well. This indicates that liquid from the system may be flowing into the well through the ground or over the surface. Water tests available from your local health department will indicate if you have this problem.
Monday, May 11, 2009
In the 1950’s when Bell Labs fist developed the PV cell operating efficiency was 4%, in the 1970’s efficiency was 9%. Currently efficiency is 15% and there are developers working on higher efficiency PV and concentrating systems. Between manufacturing cost reductions and increase efficiency we find ourselves with solar PV cells at $2 watt. Is that good enough?
Today a PV cell provides 1,000 watts per square meter (costing $2,000 at the current recession discount). At noon on a cloudless day in the Arizona desert (optimal conditions) that square meter produces an impressive 6 kilowatts hours per day. Unfortunately, most of the United States (my address included) has less than optimal solar conditions for much of the year. For the worst part of the year with the current 15% efficiency I calculate that I would get less than 1 kilowatt hour per day from that square meter of solar PV cell in the winter and rainy days, the optimal production for my location seems to be about 4 kilowatt hours per day (despite my location on a knoll and with a dead on southern facing roof). Even this level of pricing does not meet my hurdle rate of return on investment (the best use of my money). Despite my goal to someday move off the grid which will take a combination of technologies, I am tethered until solar and residential turbine technology make the next leap. Until that time, passive solar techniques are where I'm spending.
Friday, May 8, 2009
According to data compiled by Loudoun and Fauquier Counties Virginia these systems fail at a rate significantly higher than traditional systems and the majority of their alternative systems are not functioning properly. Alternative systems can provide excellent onsite waste treatment; however, they need to be maintained. My experience with my alternative system has been that on going care and monitoring is necessary to keep my system humming (literally, the motor for the air compressor to the aerobic tank makes a humming sound when it working properly). It took a considerable amount of money and effort to ensure that the system that that came with the house I bought was and remains operational.
On April 8, 2009 the General Assembly of Virginia passed HB 1788/SB 1276. According to the Piedmont Environmental Council this legislation denies localities the ability to restrict use of alternative septic systems and require maintenance of such systems. However, the legislation contains enactment clauses and HB 1788/SB1276 will force the Virginia Board of Health to finally act on the issue. Uniform regulations throughout the Commonwealth might facilitate homeowner awareness and compliance. § 32.1-164 of the Code of Virginia requires Virginia Board of Health to begin an O&M program for alternative septic systems that is based on the manufacturer’s operation and maintenance instructions, local requirements, or state rules and policies whichever is most stringent. These requirements go into effect on July 9th 2009 and remain in effect until final regulations for O&M of alternative systems are in place. The Virginia Department of Health, VDH, is currently trying to decide if these requirements would apply to all alternative systems or only those installed after July 9, 2009.
The VDH has been working to promulgate these regulations under § 32.1-164 of the Code of Virginia, since the DEQ handed over authority at the beginning of this decade. So far there are no regulations and the VDH is considering whether all the alternative systems installed in the past decade should be regulated in the interim. Developing appropriate, fair and functional regulations that will serve homeowners, and protect all the waters of the state is a difficult task that certainly will take time. However, ignoring the existing inventory of alternative systems that require maintenance to function for the duration of time that it will take to develop and implement regulations would appear irresponsible and not protective of the homeowners. All too often homeowners are unaware they have a problem until sewage is backing up into their homes or surfacing in their yards. Simple consistent interim regulations could prevent that.
The US EPA has found that adequately managed decentralized waste water treatment systems are a cost effective long term option for meeting public health and water quality goals in less densely populated areas. So, let’s manage them correctly. While the VDH works to develop regulations, in order to protect health and local water resources, what’s left of our property value, and conservation of groundwater, they should create a default O&M schedule of once or twice a year for all alternative systems installed before July 9, 2009. The three manufacturers I checked with had almost identical maintenance recommendations for their systems. The VDH should pick one and apply it to every alternative system currently in operation.
Wednesday, May 6, 2009
In the “1996 Report to Congress on the National Water Quality Inventory” the second most frequently cited contaminated source for water was improperly constructed and poorly maintained septic systems causing nutrient and microbial contamination to groundwater. In that survey 500 communities were noted to have had public health problems caused by failed septic systems. In 2003 EPA reported that 168,000 viral and 34,000 bacterial illnesses occur each year from drinking water contaminated by waterborne pathogens from fecal contamination. Proper maintenance of septic systems (both traditional and alternative) is essential for protection of public health and local water resources. In 1996 more than 25% of existing homes and 33% of new developments were served by septic systems. The EPA estimated that by 1999 over 30% of the households were served by onsite septic systems, and that number has probably crept up with the building boom that took place in 2000-2006. More than half of the existing onsite systems are over 30 years old and 10% of these older systems back up into homes or yards each year. Reportedly, the homeowner was unaware that there was a problem with their system until it backed up. This problem will only be made worse by the increasing number of alternative systems that require more maintenance. Long before global warming impacts the earth’s populations; lack of clean reliable potable water will. Our water resources need to be protected.
My libertarian streak would love to believe that homeowners would care for their septic systems appropriately to avoid the system backing up in the future, contamination of the groundwater (which may be the source of the local drinking water), and future septic system repair bills of tens of thousands of dollars to remediate and replace a system. Unfortunately, many homeowners are unaware of how septic systems work and what is necessary to maintain them. In addition, people do not seem to be able take appropriate responsibility for their systems. One method to deal with this problem is to eliminate all but the most basic systems in the most geologically favorable locations (reduce percolation rate tolerances and design the systems as conservatively as possible). The other method is to regulate, control and track. Establish system performance and monitoring and maintenance requirements, establish a tracking system and operating permits for compliance monitoring, and establish fee system and fines to fund and enforce the program. As a society we collect taxes, we license, register, and inspect cars; how different would it be to license, register and inspect/maintain a septic system. After all, unlike cars, septic systems stay put and should be easy to track.
Monday, May 4, 2009
There are many different types of septic system designs. The most common type used for single family homes consists of a septic tank and leach field. A septic tank can be an anaerobic (without air) tank or an aerobic tank (with air). The anaerobic system is a single chamber tank that receives the toilet and drain waste from the house and allows the solids to settle down to the bottom of the tank where the anaerobic bacteria that live in the tank digest the organic materials while the effluent (water around all that stuff) flows out to the leach field to be purified by passing through soil until it reaches the groundwater. Scum consisting of oil and grease floats on top of the water layer and can be pulled into the leach field limiting its effectiveness.
The septic tank effluent water is either pumped or allowed to flow to a leach field or other soil absorption system, where it percolates into the soil, which provides final treatment by removing harmful bacteria, viruses, and nutrients. Suitable soil is necessary for successful waste water treatment. The “percolation rate” is the rate at which water moves through soil. The acceptable rates are between one minute and one hour per inch of soil. Take either more or less time for the water to pass through your soil and the natural soil is unsuitable for treatment of the waste water. If the water moves too slowly through the soil the leach field will flood with contaminated, foul smelling water or the water will back up into the house. If the water moves too quickly thought the soil the water will be untreated and contaminate nearby ground or surface water.
An aerobic system consists of a multi chamber tank or several tanks. After separation of solids in the first tank waste is forced through a filter into a second chamber or tank where air is pumped in to enhance aerobic bacteria which decomposes the organic material. The waste then flows into a third chamber or settling chamber which collects the bacteria and passes the liquid on to the leach field or drip field. Aerobic systems can remove more than 90% of the organic material and suspended solids within the tanks themselves, but require much more maintenance. (These systems are like the British sports cars of the septic world.) The biological load delivered to the leach field or other absorption system is much reduced and would allow (if permitted under regulation) the successful treatment of septic waste where soils are rocky, impermeable or groundwater is particularly shallow.
Indoor water use in the typical single-family home is between 50-70 gallons per person per day. Septic systems are sized by bedrooms, which is an estimate of the number of people living in a home. However, even if the number of people living within your home is appropriate for the size of the septic system, you can still overload the system. Use too much water in a short period of time and the system will be overwhelmed. Each time the system is overwhelmed untreated sewage will leave the tank and begin to clog the leach field. A leaky toilet alone can add as much as 200 gallons of waste water to the system each day. The less water used the less water enters the septic system, and reduces the risk of failure. If the amount of waste water entering the system is more than the system can handle, the waste water containing raw sewage eventually backs up into the house or yard and creates a health hazard. By the time you can smell or see a problem, however, the damage to the leach field might already be done. Replacement of a leach field can run to the tens of thousands of dollars. So caring for your septic system not only cares for the earth but also cares for your wallet. By limiting your water use and spreading out peak demands on the system you can reduce the amount of waste water your system must treat. When you have your system inspected and pumped as needed, you reduce the chance of system failure.
The US EPA’s Homeowner’s Guide to Septic Systems is a terrific basic guide to caring for and maintaining your septic system. Follow the Dos and Don’ts and your septic system may last forever. Remember though, what goes into your septic system goes into the earth. Rethink the products you use to clean your house. Paint, solvents, gasoline, insecticides and poisons should never go down your drain. Every chemical you pour down your drain is buried in your yard. In a multitude of ways your yard is part of the earth’s yard.
Friday, May 1, 2009
After six months electricity usage (as measured in kilowatts for the same six months the previous year) had been reduced by 6% and the winter liquid propane usage (as measured in volume use December through March both years) was reduced by 25%. Also, the overall comfort in the bedroom over the garage and the master bedroom has been vastly improved. I was very surprised at the energy savings for what was a well insulated home.