Transcript Wastewater Reclamation System for the Salisbury School

Prepared by WMC Consulting Engineers Inc.
John A. Wengell
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Student Population Fluctuates between 230
students to 300 students
50 Faculty Members & 70 Staff Members
Water Usage 23,200 GPD (Averaged- School in
Session)
Population Fluctuates – Added 15% Variation
= Average 26,700 GPD
Design Flow with a 50% Safety factor (DEEP
requirement) = 40,000 GPD
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Connect to the Town of Salisbury wastewater
treatment system (2+ miles)
Construct a standard type leaching system
Install a pretreatment system and disperse
effluent via low pressure to constructed
leaching bed with an additional leaching layer
Install a pretreatment system and disperse
effluent via low pressure to constructed
leaching bed and thru a series of wetland cells
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Use of enhanced pretreatment with deemed
cost effective
On Site disposal allows for groundwater
reclamation into existing groundwater system
Variety of enhanced pretreatment options
approved by DEEP
Reduction of cost with installation of wetland
cells over additional leaching layer needed to
achieve 21 days of travel time
1.
Zenon Systems (Cycle-Let) Technology
consisting of pretreatment, anoxic and aerobic
stage biological treatment, ultra-filtration
membrane separation, carbon adsorption and
UV disinfection
2.
Constructed Fill Leaching System
3.
Constructed Wetland Cell System
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Zenon System is capable of treating Nitrogen to
levels less than 10 mg/L
Zenon System is capable of treating Total
Phosphorus to levels less than 2 mg/L
Researched and proven to remove total
coliform to levels < 2.2 MPN/100ml and virus
to levels exceeding 99.998%
Performance around State
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Effluent dispersed via low pressure dispersal
system into leaching bed (18” Washed Stone)
Effluent flows thru a constructed fill layer 24”
thick of unsaturated material
To avert concerns of mounding a 12” blanket
drain of highly permeable material was placed
below the leaching fill
Allowed to break out at the toe of slope into a
collection swale
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Wetland Cells were designed to provide 100%
bacteria/virus removal back-up to the Zenon
System
Wastewater treatment via constructed
wetlands can provide high levels of bacteria
and virus removal efficiencies at Hydraulic
Residence Times (HRTs) of five to seven days
To comply with DEEP requirements the
Wetland Cells were designed to have an HRT
of a minimum of twenty one days.
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Cells were designed to retain 21 days of inflow
minus losses
Inflow = Treatment Plant design Flow plus a
50% safety factor, Direct Rainfall into the cells
and overland flow from run-off
Losses = Infiltration, Evaporation,
Transpiration and Cell Overflow
Conservatively Losses were only computed for
Evaporation
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Inflow (7,255 c.f./day) – Losses (567 c.f./day) =
6,688 c.f./day
Storage of 140,448 c.f. necessary for 21 day
requirement
Approximately 69,000 s.f. of pond area at a 2’
depth was constructed
Discharge Rate of 35 gpm spread over 150’ long
level spreader