Design Solutions: Dealing With New Code Issues

Transcription

1 Design Solutions: Dealing With New Code Issues MOWA 2013 Winter Conference - Alexandria, MN Glen Schilling St. Peter Well Drilling Adv. Designer, Adv. Inspector, Service Provider, Installer, Maintainer Tim Haeg Watab Inc. Adv. Designer, Adv. Inspector, Service Provider, Installer

2 Changing the Rules MPCA Subsurface Sewage Treatment Regulations Rule update process started in the early 2000 s Request for comments / public hearings / SONAR Rules were adopted & printed in the State Register 01/28/2008 Adoption of the new rules coincided with an economic recession Some Counties adopted the new rules right away, others delayed Transitions were sometimes difficult, problems found Rules further revised & refined in 2011

3 The New Rules Chapters

4 4 Parts of the New Rule 7080 & 7081: Minimum technical standards for individual and mid-size SSTS; 7082: A framework for local administration of SSTS programs; 7083: Statewide licensing and certification of SSTS professionals, SSTS product review and registration, and establishment of the SSTS Advisory Committee.

5 Product Registration Advanced Treatment Devices Soil Dispersal Media

6 Tank Testing & State Listing Product Listing on MPCA website & Product Ready for Installation

7 New License Categories Basic Designer: Types I-III, <2,500 GPD Intermediate Designer: Types I-V, <2,500 GPD Advanced Designer: Types I-V, <10,000 GPD No more Designer I or Designer II categories Increased Training, Mentorship

8 SST S Subsurface Sewage Treatment Systems System Classification (Types) Type I: Trenches, Beds, At-Grades, Mounds, Graywater Systems; Type II: Floodplain Areas, Privies, Holding Tanks; Type III: Non-typical soil-based systems; Type IV: Performance based systems using registered products Pre-Treatment Reduced Size Reduced Separation; Type V: Engineered Performance systems.

9 3 soil observations per site One must be in the area having the most limiting condition Must be within the site borders Hand augers or probes, or pits Soil observations before perc tests Be careful not to disturb the site

10 County Soil Verifications Soils must be verified prior to permitting Every county procedure is different: Meet Designer on site County performs testing County sub-contracts County makes Designer take care of it

11 Rapidly Permeable Soils In sand or loamy sand (perc rates 0.1 to 5 MPI) Pressure Distribution; or Maximum trench area 15% of total required area; or Vertical separation of at least 5.

12 High % of Rock Fragments Rock Fragments means anything larger than 2mm, and includes gravel, stones, cobbles, and boulders 50% treatment credit for soils with 35% to 50% rock fragments No treatment credit for soils with >50% rock fragments Dispersal media cannot contact soils with >35% rock fragments.

13 How to determine % of Rock Fragments Field Estimation Sieve analysis University of Minnesota has testing protocol available on their website

14 Calculating Separation Determine the depth to the limiting condition (redox, water, bedrock, etc.) Determine the treatment capacity of the dry soil (100%, 50%, 0%) Make sure the necessary separation will exist; Otherwise, design soil corrections or above-grade system.

15 Worksheets UofM design worksheets are widely accepted by many LGU s; Other design worksheet formats are also available; Make sure design report is comprehensive; Installers & Regulators may need to refer to different parts of the report.

16 Management Plans UofM offers several general and technology-specific plans; Important to communicate with the owner of the system; Can be tailored further by the designer; Consider offering the Owner s Guide in addition to the plan; Not a substitute for common sense.

17 Tanks with less than 2 feet of cover must be insulated Durable, water resistant insulation; R-Value of 10 or more Maintenance hole covers must be insulated

18 All Maintenance Hole Risers to Finished Grade Prevent surface water run-on; Risers must be water-tight; Maintenance hole covers must be insulated; Consider riser material choices for water-tightness, settling & finished grade accuracy.

19 Increased Septic Tank Sizes More capacity can mean more tanks More maintenance hole covers More tank fees for the installer

20 Effluent Screens Recommended in 2011 where they had been required in 2008; Tank registration list requires in some cases; When installed, alarms are required; Make sure alarms are labeled; Owner needs to be aware.

21 Pressure Distribution Systems Pressure required on all beds >12 ; 1/8 perforations allowed; 3 foot maximum spacing of perforations and laterals; Worksheets address details, pay close attention.

22 Cleanouts on Laterals Required on all pressure distribution systems Protect with valve boxes No HARD 90 s Optional shut-off valves for each lateral How specific are designers about the details?

23 Flow Measurement Required for all Other Establishments Required for all systems which use a pump Can be accomplished with a pump cycle event counter and/or elapsed time meter Only accurate if it s calibrated

24 Float Settings Rules require specific dose volumes; Installer must follow design closely to achieve correct dose; Some factory floats can t be set for small doses; Special floats are available, or use timers for specific doses.

25 Other Establishments Design Parameters Flows provided for Other Establishments; Can use flow equalization to downsize components after EQ Cannot discharge anything stronger than residential waste strength to a drainfield; organic loading rates to soil Pre-treatment may be required.

26 Larger SSTS (LISTS) 2, GPD Nitrogen Requirements Operating Permits Design Guidance

27 Mid-Sized Systems (MSTS) 5,000-10,000 GPD Aquifer Assessment Nitrogen Requirements Operating Permits Groundwater Mounding Design Guidance

28 Glen Schilling Tim Haeg Thank You!