, 157 ETA system, 175, 176, 186-187 Coliform bacteria. See Bacteria ET/overflow system, 187 removal Evaporation rates, 177, 179-181 Collected subsurface sand filter, Evapotranspiration water budget, 161-162, 169, 170-173 181-184 250 ONSITE WASTEWATER DISPOSAL Flood irrigation, 134, 136-139 Percolation Flooding, 33 rate, 30, 32, 87, 107 test, 27-30,86-88,109 control, 74, 75, 101, 165 rates, 119 curve, 62 Friction loss, 119-121, 148, 149 dosing, 53, 59-62 Furrow irrigation, 135, 139 selection, 59-62, 121-122, Garbage disposal, 44, 69, 160, switching, 63, 64 205, 210, 233-234 Permeability, 26-27. See also Gas bubbles, 43, 46-47 Percolation rate Geotechnical fabric. See Barrier Plumbing, 39, 204 material Pore space, 18, 26 Grease, 8 Pressure reducing valve, 232 Ground water Pathogens. See Bacteria, Viruses clearance, 7, 14, 154 Plants, 22-24, 81, 133, 137-138, level, 17 178, 191-192 quality, 1, 197 Plot plan, 16 seasonal high, 22, 32 Grey water Recirculating sand filter, 164-167, quality, 203, 210 171-172 tank, 205-206 Retrofits, watersaving, 230-232 Retention time irrigation, 205 filtration, 207-208 septic tank, 8-9, 44 volume, 208 disinfection, 212-213 Reuse, water, 198, 203-204, Infiltration, 109, 226 206-207 Intermittent sand filter, 162-164 "Rootcanal," 226-227 Roots, 81, 98, 223 Laboratory testing, 216-217 Risers, 46, 49-50 Leaks, water, 229 Leveling, 76-78, 84 Salt buildup, 178, 193 Lifetime of system, 8, 12, 65, 100 Sand, 18, 155-156, 158, 179 Lime, 225 Setback distance, 7, 40, 49, 72 Loading rate, 31, 143-144 Settling efficiency, 45 Slime layer. See Biological mat Microorganisms. See Bacteria removal classification, 18-21 Mottling, soil, 22, 23 color, 22, 23 Nitrogen, 10, 194, 197, 235 peds, 24 poorly trained, 22 Odors, 9, 134 pore space, 18, 26 OSHA standards, 18 profile, 16, 18 Oxygen, 9, 10, 205. See also saturated, 14 Aerobic treatment unit sieve, 158-159 INDEX size, 18-19, 159 filters, 154, 208-210 structure, 24-26 disinfection units, 211 surveys, 16-18 System texture, 21, 23-24 failure, 12 well drained