Proximity Lot Details

This table lists details of the wells and drainfieds of each of the lots. Below the table is an explanation of what all these numbers mean. We've also included some cost estimates for system installation. Kevin Oliveau (oliveau@aol.com) will be happy to answer any questions you might have.

Well Yield: Loudoun County requires all homes to have a well with flow rate of at least one gallon per minute (gpm). One gpm may not sound like much, but that works out to 1440 gallons per day. Typical consumption is 75-100 gallons per day per person which means that a 1 gpm well will support about 15 permanent residents in your home.

What about flow rates? You may be using more than 1 gpm at times (someone is in the shower, the washer is on, the dishwasher is on). But there is a large amount of stored water in the system. The lower yielding wells are very deep. Any well fills with water to within 30 ft of the surface and the pump is 20 ft from the bottom of the well. You get 1.5 gallons per 1 ft of filled well. So, for instance, Lot 15 (yeild 1gpm) has 650 ft of filled well as a buffer, which works out to 975 gallons buffered before the well runs dry. Similarly, Lot 6 has 825 gallons of stored water. So even if you're taking two showers, washing clothes and running the dishwasher simultaneously, you'll be fine. The one caveat is leaving the garden hose on too long. Full blast, a garden hose can consume 5-7 gallons per minute.At that rate, one of our 1 gpm wells will run dry in about two hours and burn out the pump.

Well system costs: A complete installed system (well, pressure tank, plumbing, 50 ft. trenching) runs $2,500 to $4,000. Zoning regulations requre the well to be at least 50 ft. from the house. If the well is more than 50 ft. from the house, additional trenching/pipe costs will run you $2.75/ft. If you burn out a pump, it will cost you $1,200 to $1,500 to replace. You can install a low-water-level shutoff to protect the pump for about $500.

Drainfield Capacity: Each drainfield is measured in terms of the number of people it can support. One bedroom equals two residents. Thus, a four bedroom drainfield will support eight permanent residents in the home.

Drainfield Reserves: Each lot comes with two drainfield sites, a primary (which you instaill when you build your home), and a designated reserve (which may never be installed). These sites are usually adjacent. Sometimes algae form in the drainfield pipes, cloging them. When this happens, you install a new drainfield at the reserve site. Without nutrients, the algae in the primary field die off. If the reserve clogs you shift back to the primary, and so on. This is why only two sites are needed.

Pumped Drainfields: Almost all of our drainfields are higher up than our building areas. This means that we will have to pump to our drainfield sites (as opposed to a gravity driven system). While this is more expensive, it does reduce the chances we will ever have to use our reserve sites. Because a pumped system waits until it has enough effluent to pump, it loads the drainfield more evenly than a gravity system. This means that the nutrients are distributed over a larger area, providing a lower nutrient density at any given point. A lower nutrient density means less chance algae can clog up the system.

Low Pressure and Pureflow: One way to boost the capacity of a drainfield is to put it under low pressure, which requires about $2,000 in extra equipment. Another, more expensive system is Pureflow, which involves altering the soils of the drainfield. In the table above, we've listed some cases where the primary system is conventional, but the designated reserve uses one of these technologies to increase capacity. Because the reserve is unlikely to be needed, it costs nothing to designate the reserve as low pressure or Pureflow. But it increases the area available for the primary contentional site, which increases the capacity.

Drainfield Costs: An installed pumped drainfield will cost about $10,500. Trenching costs will be $3-5/ft. If you go with a low pressure system, the cost increases to about $12,500. Pureflow is the most expensive, and varies with the size of the drainfield.