Wastewater disposal by conventional septic usually is the most straight-forward and cost-effective to evaluate, engineer, design and operate. Permitting a conventional septic disposal system requires soils with suitable percolation rates, and adequate thicknesses (generally four feet) of unsaturated soil to provide for additional land treatment of the wastewater being applied. Large volumes usually require pre-treatment. ALWI’s relevant experience is exemplified by one Frederick County, Maryland project where ALWI is completing a soils and hydrogeologic feasibility and permit application evaluation for a 52,000 gallon-per-day conventional septic disposal system.
When the site soils are unsuitable for disposal by conventional septic disposal, alternative and unconventional methods of wastewater disposal may be considered. These include spray irrigation, drip irrigation, sand mounds, rapid infiltration basins, and overland flow systems. Double-ring infiltrometer testing within shallow limiting horizons usually is required, and groundwater mounding during seasonally-high water table conditions can impose permitting constraints. ALWI’s hydrogeological and hydrological staff is adept at working closely with regulatory agency personnel in performing the needed studies and evaluations in a timely and cost-effective manner while still remaining focused on client-oriented solutions.
Representative professional services performed by ALWI’s wastewater division include the following:
- Soil Infiltration, Permeability & Infiltrometer Tests
- Monitoring Well Design, Sampling & Monitoring
- Nutrient Loading Analyses & Nitrogen Balance Calculations
- Groundwater Mounding & Hydrologic Mass Balance Evaluations
- Horizontal Hydraulic Conductivity / Slug Tests
- TMDLs and Chesapeake Bay Protection
- TMDL Planning Evaluations
- Pond & Lagoon Leakage Evaluations
- Permit Applications, Regulatory Coordination & Expert Testimony