NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Soil Interpretation Septic Systems – Can we do better?

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Name change Onsite wastewater treatment and dispersal system

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Current Interpretations Soil depth (separation distance) –Based on 1948 Public Health Service –120 cm needed to “restriction” Slope “Perc” rate –Too slow –Too fast Hydraulic measurements

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE State Code – Interpretations? Soil depth (separation distance) –Focus on treatment –45 – 60 cm needed for treatment Slope –Slope correction –Installation up to 30% NO perc test System sized on soil properties

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Georgeville – fine, kaolinitic, thermic, Typic Kanhapludults Soil Survey Interp – Moderate – percs slow Local Health Dept. Interp – Suitable

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Revised Interpretation Conventional system as a baseline Modification to a conventional system results in more limitations –Fill over system –Slope issues (< 30%) –Mineralogy (clay only) All of above lead to a issue with soil depth

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE 117 cm 45 cm 30 cm 15 cm 30 cm 15 cm A” 30% slope 90 cm trench x A = S x W A = 0.3 x 90 A = 27 How much soil is needed? Td = = 117

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Slight

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Note all depths are slope corrected ≥ cm 30 cm 30 cm or more Conventional (≥105 cm of usable soil) Unsuitable Material 30 cm cm 15 cm Shallow Placed (90 cm of usable soil) Unsuitable Material

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Moderate

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE cm 30 cm 15 cm Suitable Cover Ultra-shallow or At-grade (75cm of usable soil) Note all depths are slope corrected Unsuitable Material

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Severe

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE 45 to 60 cm unsuitable Suitable Fill Fill System Note all depths are slope corrected 30 cm Suitable Cover 15 cm cm 30 cm Unsuitable Material

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Unsuitable Material Clay mineralogy –Very sticky –Very Plastic –Very Firm Water table –Aquic –Oxyaquic Impermeable –Rock –Horizons – root restrcitive

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Unsuitable

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Additional variables Coarse fragments Slope –Depth –Installation Equipment Stabilization Silt content Mica content Slope –Position –Description

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE What about a “perc” test? Saturated hydraulic conductivity (Ksat)

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Hydropedology of a Benchmark Carolina Slate Belt Catena NCSS – NCSU Research Project

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Georgeville-Tatum-Chewacla Catena

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE LTAR – Soil Survey, Lab, Field, Morphology Soil Survey: 0.75 to 2.5 gpd/sq. ft.

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Recomendations Review current literature on treatment and dispersal Use a conventional system as a baseline –Suitable for conventional - SLIGHT –Ultra-shallow – Moderate –Fill or at-grade - Severe Adapt to state code as needed Consult with CIDWT for additional detatils