PPSSD PUBLIC HEARING
July 6, 2010
The meeting was opened by Chairman Nevalainen at 7:00 pm and immediately handed over to SEH Engineer, Julie Kennedy. Ms Kennedy introduced herself and asked if everyone in the room was up to speed with the PPSSD. Julie gave a brief explanation to the group about reason for the meeting, the Addendum to the Preliminary Engineering Report.
The purpose of the addendum is to provide an update to the treatment system with respect to the Minnesota Pollution Control Agency nitrogen policy and treatment system suitability and to further evaluate an alternative for seasonal woodland irrigation. The addendum includes these updates to the PER; Design Basis Update, Nitrogen Removal Policy, Treatment System Suitability, Seasonal Woodland Irrigation/Infiltration Bed System, Recommendations.
Design Basis Update; In section 4.3 wastewater design loadings of the PER, mass loadings were provided in Table 4.4 based on an equivalent design population of 253 and typical per capita loading factors. In Appendix F of the Amended PER dated May 2007, a revised flow of 22,000 gpd was provided. Table 4.4A provides an update to the design loads based on the increase in the projected wastewater flow from 20,000 gpd to 22,000 gpd (a 10% increase). Design flow and loading assumes the inclusion of the Wooden Frog Campground.
Nitrogen Removal Component; The MPCA has a Large Subsurface Treatment System (LSTS) ground water nitrate nitrogen policy. This policy requires every new LSTS to achieve a 10 milligram per liter or less nitrate nitrogen concentration in ground water at the property boundary or nearest receptor. The policy includes two permitting options. Option No. 1 requires an abridged hydrogeologic assessment.. Option No. 2 requires a complete hydrogeologic assessment and a ground water monitoring well network
The project has a projected design flow that is above 10,000 gpd and therefore the system is classified as an LSTS. AS an LSTS, the treatment system will need to be designed to meet the MPCA nitrate nitrogen removal policy. The PER selected option No. 1. However, for this project, it is recommended that a pretreatment treatment system be provided to meet an EOP limit of 10 mg/L total nitrogen under permitting option No. 1. Option No. 1 is a guaranteed method of complying with the nitrogen policy.
Treatment System Suitability; because of the reliability of the aerobic treatment units to provide treatment throughout the year, the aerobic treatment unit is recommended over the constructed wetland.
Seasonal Woodland Irrigation; the use of a woodland irrigation system during summer would preclude the system from falling under the design requirements of an LSTS. However, nitrogen treatment would be addressed in the design as well as the requirements for disinfection. The woodland irrigation system would be designed to minimize environmental disturbance.
Recommendations; The recommended system includes a STEP collection, aerobic treatment, seasonal woodland irrigation with offseason infiltration beds.
Questions asked were about the timeline for the work to be done and cost. Brett Balavance commented on the permitting process. EDU versus monitoring of business parcels. Mr. Balavance stated that Debt service and operating and maintenance stated individually on a statement works very well.
Mary Manninen, Clerk
See attached attendance list