Posts

Comment

Does it make sense to proceed on a path that treats the entire wastewater stream to a level that may be required for discharge to the Gallatin? If a majority of the volume of wastewater is intended to be used for golf course or other irrigation purposes, why would the district go to the expense of treating to further reduce the nutrients that are allowed for irrigation?

Response

Advanced treatment final design is several years out. At that time, a decision will be made as whether to treat all flows through Advanced Treatment or only those flows going to subsurface, or snowmaking, or direct discharge, or some combination of those. The issue with this is that “fit for use” distribution could require multiple distribution pipelines.

Comment

My concern with going down a path that recommends the latest and best available technology is that often these new and emerging systems have not been adequately refined to represent a reliable and efficient treatment system.

Response

Understood. MBR is not a new and emerging technology, it is approximately 25 years old at this stage, with well over 500 installations in the U.S.

Comment

TM 14: Surface Water Discharge
Question: Is algae (chl a/biomass) required as part of the permitting process?

Response

No, not at this time. Nutrient modeling can be used to predict chloraphyll A, but chlorophyll is not currently used by DEQ in discharge permitting.

Comment

TM 13: Reclaimed Water Irrigation
Comment: I would not estimate what is possible to irrigate on the golf courses/community park by assessing historical numbers for the effluent released by the district. The district has not been irrigating to agronomic uptake. Instead much of the “irrigation” is essentially disposal and way past agronomic uptake. Refining irrigation calculations should be a priority to reduce nutrient loading to the Upper West Fork/Middle Fork.

Response

This is debatable, based on analyses by Jacobs (formerly CH2M Hill), HKM (Dowl) and MBMG. Regardless, the actual irrigation values are within the calculations of these various groups.

Comment

TM 12: Question: to replace the drainfield at FMS, what was the reasoning to double the existing structure. Could the structure be more than doubled? Also if nitrogen concentrations in the treated wastewater effluent are significantly less (?10X or so) than that of the septic system couldn’t it be argued for a much higher flow limit in the permit?

Response

More than doubling the infiltration at that location could potentially lead to mounding of water and this could lead to flow paths, and mixing zone impacts that are difficult to predict. More research on groundwater and strata is needed to just permit the doubling of infiltration. In the process of that research effort, additional disposal capacity could potentially be identified. Data collected during operation will also provide information on whether the ultimate disposal capacity can be increased at this location.

Comment

TM 12: Indirect Subsurface Discharge
Comment: You analyzed the best option as FMS. Are the other two sites also viable. Why not explore more than just one?

Response

The other three sites (Horse Pasture / Tract B, the old golf course driving range, and the District property southeast of the WRF) are not as viable based on a preliminary review of the hydrogeology in those areas (shallow groundwater, shallow bedrock/shale, close proximity to surface water, and/or close proximity to drinking water wells) and discussions with DEQ.

Comment

TM 11, Comment on Figure 3: Where did you obtain Middle Fork discharge? If it is from the Task Force station, I would remove the winter data as it is impacted by ice and unreliable.

Response

Thank you for providing this information, it will be removed or otherwise statistically treated to remove outliers.

Comment

TM11  – Executive summary      Question: Where did the 185 MG for Direct discharge come in Table 1 – shouldn’t it be <=70 MG?

Response

Again, two different numbers. The 185 MG is simply an estimate for what the District might request to account for potential failures to reuse infrastructure, extreme weather events, etc. The lower values are placeholder approximations of what annual disposal may be necessary depending on continued development of other disposal alternatives, weather years, occupancy rates, etc.

Comment

TM1: I understand that MBR would treat effluent to a much lower level of nutrients than the current system. Would the same variability of effluent nutrients be expected with MBR treatment as shown in Figure 1 of the TM1 Executive Summary?

Response

No. MBR performance, with chemical addition, should be much more consistent than the existing treatment performance.

Comment

This point may be mute but I was told of a new disposal system at the hospital for medications. Has this been promoted by the district? A PR campaign may be beneficial to try and reduce the CECs from the source.

Response

Agreed.