Figure: 30 TAC 285.91(8)

Table VIII. OSSF Excavation Length (3 Feet in Width or Less).

  Excavation Length (Feet)
  Soil Class Ib Soil Class II Soil Class III
Daily Sewage Flow (Q)2 For 1.5 Foot Excavation Width3 For 2.0 Foot Excavation Width For 3.0 Foot Excavation Width For 1.5 Foot Excavation Width3 For 2.0 Foot Excavation Width For 3.0 Foot Excavation Width For 1.5 Foot Excavation Width3 For 2.0 Foot Excavation Width For 3.0 Foot Excavation Width
100 75 66 53 114 100 80 143 125 100
125 94 82 66 143 125 100 179 156 125
150 113 99 79 171 150 120 214 188 150
180 135 118 95 206 180 144 257 225 180
200 150 132 105 229 200 160 286 250 200
225 169 148 118 257 225 180 321 281 225
240 180 158 126 274 240 192 343 300 240
275 207 181 145 314 275 220 393 344 275
300 226 197 158 343 300 240 429 375 300
325 244 214 171 371 325 260 464 406 325
360 271 237 189 411 360 288 514 450 360
375 282 247 197 429 375 300 536 469 375
400 301 263 211 457 400 320 571 500 400
420 316 276 221 480 420 336 600 525 420
450 338 296 237 514 450 360 643 563 450
475 357 313 250 543 475 380 679 594 475
500 376 329 263 571 500 400 714 625 500


1. To determine excavation lengths, greater than 3 feet in width or where the area and width are known, use the formulas provided in 285.33(b)(1)(A)(vii).
2. To determine excavation lengths (3 feet or less in width, but greater than or equal to 1.5 feet in width) for daily sewage flows (Q) not provided in this table, use the formula provided in 285.33(b)(1)(A) (vii)(III).
3. Minimum excavation width is 1.5 feet for all excavation lengths.