SEC, Inc. is one of the few consulting firms in the State of Tennessee that designs the decentralized sewage treatment systems know as STEP systems, and with over 4,200 STEP lots designed, there are few other firms with as much experience.

With pumps in the septic tanks, they are termed STEP Systems for Septic Tank Effluent Pump. However, this does not describe the treatment process. The effluent is pumped from the STEP tank into a common force main in the subdivision. The force main delivers the effluent to a recirculating sand filter (RSF). In the RSF, the effluent receives the majority of its treatment. The effluent passes through the RSF four times before it is pumped through a disc filter and ultraviolet light effectively destroying bacteria and viruses before releasing it in a subsurface drip irrigation system. At this point, the soil continues to provide treatment on an already cleaned effluent.

When compared to the standard sewage treatment plant (STP), residential effluent from a decentralized plant measures quite well. The BOD5 effluent averages 4.0mg/L with an efficiency of 98% [vs. a local STP 4.3mg/L, 98%]. The nitrate effluent averages 0.21mg/L with an efficiency of 99.6% [vs. 5.3mg/L (nitrate + nitrite)]. The total suspended solids (TSS) are below detectable levels [vs. 0.7mg/L]. The fecal coliform average 2.3/100ml [vs. 9/100ml]. Comparing the effluent, it is easily seen that the STEP System is more effective than the traditional tertiary STP for residential effluent.

A List of SEC, Inc. Designed S.T.E.P. Subdivisions: