MPCA Design Guidance for Large Subsurface Wastewater ...

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D. Will further detailed investigation be necessary to assess the suitability of on-site soils to accept wastewater at the proposed acceptance rate? Explain why or why not. _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ 2. Unsaturated treatment zone assessment A. Estimate the height of ground-water mounding above the saturated zone. B. Evaluate the potential for vadose zone mounding above a restrictive soil layer. C. Provide your preliminary assessment regarding the long-term maintenance of an unsaturated treatment zone of adequate thickness: _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ D. Will further detailed investigation be necessary to assess whether an unsaturated treatment zone of adequate thickness will be maintained after full operation of the LSTS? Explain why or why not. _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ Design Guidance for Large Subsurface Minnesota Pollution Control Agency Wastewater Treatment Systems April 2010 39
3. Nitrogen impact assessment (for those selecting Option #2 only) This option cannot be used where the nitrogen dilution cannot be modeled, such as karst geology. A. Estimate the concentration of total nitrogen that will be delivered to the soil absorption site. B. Model nitrogen dilution using the formula in Attachment 9 or other contaminate transport model. C. Provide your preliminary assessment regarding long-term compliance with the 10 mg/L total nitrogen as N limit at the facility’s property boundary. _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ D. Will further detailed investigation be necessary to assess potential nitrogen impacts and compliance with the nitrogen limit at the facility’s property boundary? Explain why or why not. _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ 4. Phosphorus impact assessment (for systems within 500 feet of a surface water) A. Estimate whether ground water flow direction is toward a surface water body. B. Evaluate if surficial ground water discharges to the surface water. C. Determine whether soil characteristics and other information suggest a high potential for longterm phosphorus attenuation. D. Provide your preliminary assessment regarding the impact of phosphorus to nearby surface water: _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ Design Guidance for Large Subsurface Minnesota Pollution Control Agency Wastewater Treatment Systems April 2010 40
Page 1 and 2: Design Guidance for Large Subsurfac
Page 3 and 4: Table of Contents Page Introduction
Page 5 and 6: How to Use This Guidance Document M
Page 7 and 8: 1. Knowing an MPCA permit is needed
Page 9 and 10: Table 1 Average Daily Flow for Four
Page 11 and 12: • depth to seasonally saturated s
Page 13 and 14: From this evaluation, a few tentati
Page 15 and 16: Permitting Option #1 may be mandato
Page 17 and 18: • Even distribution is necessary
Page 19 and 20: orings/wells may be allowed to be p
Page 21 and 22: Infiltration Trenches Plan View Sha
Page 23 and 24: Infiltration Trenches Plan View Sha
Page 25 and 26: The worksheet in Attachment 11 shal
Page 27 and 28: e. Seasonal operational changes —
Page 29 and 30: f. When mowed the drainfield inspec
Page 31 and 32: 5) A summary of any changes made to
Page 33 and 34: f. All soil test results (density,
Page 35 and 36: Attachment 1 — Knowing an MPCA pe
Page 37 and 38: Example 2: Flow for Other Establish
Page 39 and 40: Attachment 2 — Design flow consid
Page 41: W. Average daily ground water recha
Page 45 and 46: Attachment 4A — Soils evaluation
Page 47 and 48: Attachment 5 — Pathogen treatment
Page 49 and 50: Attachment 5 (continued) — Remova
Page 51 and 52: Attachment 6 — Nitrate-nitrogen t
Page 53 and 54: Attachment 8 — Phosphorus treatme
Page 55 and 56: K _____ ft/day — saturated hydrau

MPCA Design Guidance for Large Subsurface Wastewater ...

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