COG General Forum met this evening as scheduled.
By unit vote, the five municipalities that participate in the regional parks program voted to endorse the easement, thus clearing the way for Toll Brothers contractors to start blasting and excavating in the Harter-Thomas recharge area in the coming weeks, and to ultimately build a large sewage holding tank and high-pressure sewage pipeline about a mile from our main public water supplies.
There is a lot of information to process, research and write about in coming days as construction and operation unfold, and as the political, public health and ecological consequences come into sharper view.
Some numbers to think about, for those interested in math:
- 1,093 x 100 gallons per day = 109,300 gallons per day sewage flow, using DEP 1997 Domestic Wastewater Manual. 109,300 gpd is greater than the 50,000 gpd trigger for public notice back in 2014, which didn’t happen.
- 1,093 x 70 gallons per day = 76,510 gallons per day sewage flow, using an extrapolation of the UAJA per capita sewage flow factor (1 EDU = 175 gallons per day per 2.5 people per household). 76,510 gpd is greater than the 50,000 gpd trigger for public notice back in 2014, which didn’t happen.
- 268 apartments x 175 gallons per day per EDU = 47,950 gallons per day sewage flow, using UAJA’s EDU system of 1 EDU per dwelling unit, regardless of occupancy. 47,950 gpd is less than the 50,000 gpd trigger for public notice, and it’s the calculation actually used on all currently available sewage planning documents. For 1,093 residents, this amounts to just under 44 gpd per capita.
- According to Cory Miller of UAJA during this evening’s meeting, the DEP authorized the Centre Region in 1996, through the Act 537 Plan, to use the EDU calculations of de facto 44 gpd instead of the 1997 manual’s 100 gpd calculation method, regardless of actual populations to be served, because we’re apparently extra good at water conservation around here, and our infiltration rates (the amount of stormwater that seeps into newly-installed conveyance pipes), is so very tiny. Further research needed to confirm or refute Miller’s assertions.
- Miller also stated a “safety factor” of four (4) has been used in this project design. Whether the appropriate safety factor is the same in all settings, under all geologic and climate conditions is another question for further research.
- In any case, the pump station, wet well and high-pressure pipeline as designed for the Cottages and now government-approved by Ferguson Township (December 2015), DEP (January 2016), UAJA (August 2018) and COG General Forum (this evening) are sized for 47,950 gallons per day, with a maximum peaking load capacity of 4 x 47,950 = 191,800 gallons per day.
- If it turns out that the actual daily load is 76,510 gallons per day (at 70 gpd per capita) then the peaking load will actually be 306,040 gallons per day, and the pump station as designed and government-approved will be undersized by 114,240 gallons per day.
- If it turns out that the actual daily load is 109,300 gallons per day (at 100 gpd per capita) then the peaking load will actually be 437,200 gallons per day, and the pump station as designed will be undersized by 245,400 gallons per day.
Feel free to check my math. (I’ll check it tomorrow too).