fter the test hole is backfilled, the backhoe operator will then dig an additional hole off to the side. This depth is refered to as the "perk bench". The bench is excavated to the soil profile which was specified by the field technician. The percolation test is then performed in order to determine the application rate used for the design of the septic system. The percolation test involves digging a 6 inch diameter hole that is 12 inches deep into the bench that was excavated by the backhoe operator. This is usually done with a post hole digger. The hole is then filled with a standing head of water for a period of at least 4 hours. this is called the presoak period. The MOA will waive the requiredment of a presoak for the soil if when filled with water to a depth of 12 inches, two times, it will drain away completely in less than 10 minutes each time. For most soils, a presoak is required.

fter the presoak period the percolation test is performed. The "perk" test is performed by filling the perk hole with 8 inches of water and measuring how much the water level drops in 30 minutes. If all of the water drains away in less than 30 minutes, the time interval is changed to 10 minute readings. At the end of the 30 minute period, the hole is again filled to the 8 inch level and the process repeated. A minimum of three 30 minute readings are taken. From this, the percolation rate is calculated by dividing 30 minutes by the drop in inches during the 30 minute period. The following is a general classification of the percolation rates: Less than 1 minute per inch: Coarse sands/gravels that may require the installation of a sand filter to slow down the flow of wastewater through the soil 1-5 minutes per inch: Excellent 6-15 minutes per inch: Good to Fair 15-30 minutes per inch: Fair 30-60 minute per inch: Fair to Poor 60 - 120 minutes per inch: poor Greater than 120 minutes per inch: Unsuitable for an onsite septic system

Are You Purchasing Undeveloped Land?

f possible, negotiate the transaction so that the sellers pay for the soils testing (however, you should retain the right to select the engineer), with the agreement that you will reimburse them for their costs upon closing of the sale, assuming the test results are acceptable. Bear in mind that most sellers will not be receptive to this idea. Nonetheless, by heeding this advice, you won't risk investing money into a piece of land that turns out to be undevelopable.

n addition, you should retain the right to accept, or reject, the suitability of the percolation results. The reason for this is that if you make your only stipulation that "the lot be suitable for installing an onsite well and septic system", you may be bound to purchase a lot that, although suitable, will require an investment of $25,000 - $35,000 worth of engineering and "hi-tech" septic system technology in order to make it developable. If this turns out to be the case, then you want to right to re-negotiate the price of the lot.