Table 1: Soil types and Hydraulic Loading Rates
Soil Type | Soil Textural Classification | Maximum Hydraulic Loading Rate, for residential strength effluent, gpd/sf |
1 | Gravelly and very gravelly coarse sands, all extremely gravelly soils. | 1.0 |
2 | Coarse sands. | 1.0 |
3 | Medium sands, loamy coarse sands, loamy medium sands. | 0.8 |
4 | Fine sands, loamy fine sands, sandy loams, loams. | 0.6 |
5 | Very fine sands, very fine loamy sand, very fine sandy loams; or silt loams and sandy clay loams with a moderate or strong structure (excluding platy structure). | 0.4 |
6 | Other silt loams, sandy clay loams, clay loams, silty clay loams. | Not suitable |
7 | Sandy clay, clay, silty clay, strongly cemented or firm soils, soil with a moderate or strong platy structure, any soil with a massive structure, any soil with appreciable amounts of expanding clays. Soils greater than 90% rock. | Not suitable |
Wash. Admin. Code § 246-272B-03400
Statutory Authority: RCW 70.118B.020. 11-12-035, § 246-272B-03400, filed 5/25/11, effective 7/1/11.