USING THE NEW REGULATIONS DESIGNING OWTS… Prepared for the Colorado Professionals in Onsite Wastewater (CPOW) 2014 Conference by Roger J. Shafer, P.E.

A CLASSIC EXAMPLE “THE EASY LOT”

High Mountain Rd. Well

SOIL TREATMENT AREA SIZING 3 Bedroom Home = (3) x (150 GPD) = 450 No 1.5 factor Sandy Loam Soil (16-25 MPI) LTAR = 0.6 GPD/ft² (Taken from Table 10.1) STA = 450 ÷ 0.6 = 750 ft² required USE 3 TRENCHES – 3’ WIDE BY 84’ LONG

High Mountain Rd. Well 100’ 99’ 98’

TRENCHES VERSUS BEDS Trench Cons Trenches take up more area 6 foot separation between trenches Harder to install Especially with 3+ trenches Slower to install dispersal gravel Inspection coordination can be difficult

TRENCHES VERSUS BEDS, CONT. Trench Pros Sidewall Area Three 3’ X 60’ trenches have 189 s.f. of sidewall versus a 9’ X 60’ bed has 69 s.f. of sidewall area Trench resting or alternating Maintain shallow depths on steep hillsides Greater dispersion Greater oxygen transfer Less soil compaction…

SERIAL VERSUS PARALLEL DISTRIBUTION Serial Distribution Sequential trench failure Biomat for treatment (creates unsaturated flow) Parallel Distribution Lower loading (hydraulic and organic) to the soils Allows trench resting Requires dosing (siphon or pump) Requires d-box or distributing valve

High Mountain Rd. Well 100’ 99’ 98’

IT ALL FLOWS DOWNHILL OR DOES IT?

High Mountain Rd. Well 100’ 99’ 98’

PUMP SYSTEM REQUIREMENTS Section 43.8 I – Wastewater Pumping and Dosing Systems (items to note) Floats to be mounted on a stem separate from the pump discharge assembly Discharge assembly must have a disconnect union Must have access riser to grade, and have a watertight connection to the pump tank Splice box outside the access riser Pump breaker separate from alarm breaker A switch to manually operate the pump Panels to be UL listed

EXAMPLES Not good

EXAMPLES Not goodGood

EXAMPLES Not goodGood

EXAMPLES Not good

SPECIFYING A PUMP SYSTEM WHAT TO PUT IN AND WHAT TO LEAVE OUT

SPECIFYING A PUMP SYSTEM, CONT. THE TANK; COMPARTMENT; BASIN Size State Approved Materials (concrete; fiberglass; plastic) Bury depth Risers to grade Type of risers Inlet and Outlet locations Anti-floatation Make and Model

SPECIFYING A PUMP SYSTEM, CONT. THE PUMP SYSTEM Horsepower Total Dynamic Head and Flow Rate Voltage Conventional low-head or well-style Floats (mechanical; low-voltage; transducer) Splice Box Control Panel (indoor; outdoor; etc.) Audible and Visual Alarm Make and Model

WHAT ABOUT THE NEIGHBOR’S WELL?

High Mountain Rd. Well 100’ 99’ 98’ 100’ radius Well

High Mountain Rd. Well 100’ 99’ 98’ 100’ radius Well

TABLE 10.2 SIZE ADJUSTMENT FACTORS Gravity Bed = (450 GPD) ÷ (0.6 GPD/ft²) x (1.2 factor) = 900 ft² Pressure Dosed Bed = (450 GPD) ÷ (0.6 GPD/ft²) x (1.0 factor) = 750 ft²

TABLE 10.3 SIZE ADJUSTMENT FACTOR Reduction for Chambers: Gravity Bed = (900 ft²) x (0.7 factor) = 630 ft² required Pressure Dosed Bed = (750 ft²) x (0.7 factor) = 525 ft² required

High Mountain Rd. Well 100’ 99’ 98’ 100’ radius Well

High Mountain Rd. Well 100’ 99’ 98’ 100’ radius Well 100’ radius

ADVANCED TREATMENT LOADING RATES

SOIL TREATMENT AREA SIZING 3 Bedroom Home = (3) x (150 GPD) = 450 GPD No 1.5 factor Sandy Loam Soil (16-25 MPI) LTAR = 1.0 GPD/ft² (Taken from Table 10.1 for TL3N) STA = (450 GPD) ÷ (1.0 GPD/ft²) = 450 ft² required Pressure Dosed Bed = (450 ft²) x (1.0 factor) = 450 ft² No additional reduction for chambers Compared to 525 ft² for a bed with chambers Not that much difference!

MINIMUM DISTANCES PRESSURE DOSING REQUIRED ITEMOWTS DESIGN CONSIDERATION Treatment Levels 1 and 2 Treatment Level 2N Treatment Level 3 Treatment Level 3N Horizontal Separation Distances 1Distance from soil treatment area to on-site well Greater than or equal to 100 feet Greater than or equal to 75 feet 2Distance from soil treatment area to pond, creek, lake, or other surface water feature Greater than or equal to 50 feet Greater than or equal to 25 feet 3Distance from soil treatment area to dry gulch or cut bank Greater than or equal to 25 feet Greater than or equal to 10 feet Vertical Separation Distances 4Depth in feet from soil treatment area infiltrative surface to restrictive layer or ground water 4 feet (3 feet with pressure dosing) Greater than or equal to 2 feet

High Mountain Rd. Well 100’ 99’ 98’ 100’ radius Well 100’ radius 75’ radius Alt. area

REAL-WORLD EXAMPLES

> 25 feet with TL3N Soil Treatment Area Residence Treatment Unit Stream Retaining Wall

STREAM PROPERTY LINE HOUSE WELL SOIL TREATMENT AREA TREATMENT UNIT > 25’ with TL3 <75’ with TL3

WHY USE ADVANCED TREATMENT? Separation Distance Reduction Horizontal and vertical Required by County Special Watershed Requirement Lot Size Requirement Distance Reduction to Wells (for counties with greater distance requirements) Higher loading rates = smaller STA If you don’t use chambers or chamber reduction not allowed in your county

WHY USE ADVANCED TREATMENT, CONT. In Very Clayey Soils Biomat plugging a bigger issue in clayey soils An accumulation of risk factors Development Density Shallow bedrock or ground water Proximity to surface water Lack of repair field location Steep slopes

QUESTIONS? ROGER J. SHAFER, P.E