January 2009NJDEP – OPSC

www.nj.gov/dep/opsc

Overview of the Model Builder Application to Estimate Future Sewer Wastewater Flow and Septic Units

Draft Data Flow Chart

Description of the Model Builder Application

Parcel Base Methods

3/2008

Method 1 - Select greater or equal to minimum lot size after subtracting only LULC Urban 2002 from lot areas.

Method 2 - Select greater or equal minimum lot size after subtracting LULC Urban 2002 and Environmental Constraints from lot areas.

Environmental Constraints = a) C2 waters - 50' Bufferb) C1 waters - 300' Buffer c) Wetlandsd) Preserved Farmse) Open Space f) Surface water g) Municipal/ County Defined Feature

Method 1 - GIS Steps

1) Erase - LULC Urban 2002 from Parcel Layer2) Identity - Township zoning into Parcel Layer 3) Re-select - Remaining Parcel area > zoning minimum lot size – keep parcel

(Update output by removing Urban interpreted from Aerial 2007)4) Identity - Update Sewer and Septic Area 5) Identity - Open Space and Preserved Farms 6) Identity - HUC 11 joined to NO3 dilution densities7) Identity – HUC 14 for Highlands Region8) Identity - Water Purveyor Areas9) Erase - Environmental constraints in remaining Sewer lots.10) Erase - Wetlands and surface water in remaining Septic lots.11) Calculate - New Residential Units and Non-residential Floor Area 12) Quality Control - field verification of mapping and database results by County/

Municipality

Method 2 - GIS Steps

1) Erase - LULC Urban 2002 and Environmental constraints from Parcel Layer2) Identity - Township zoning into Parcel Layer 3) Re-select - Remaining Parcel area > zoning minimum lot size – keep parcel

(Update output by removing Urban interpreted from Aerial 2007)4) Identity - Update Sewer and Septic Area 5) Identity - Open Space and Preserved Farms 6) Identity - HUC 11 joined to NO3 dilution densities7) Identity – HUC 14 for Highlands Region8) Identity - Water Purveyor Areas8) Calculate - New Residential Units and Non-residential Floor Area 9) Quality Control - field verification of mapping and database results by County/

Municipality

Working Draft Model Builder Application

Minimum Lot Size Selection (Method1 Example)- Update output by removing Urban interpreted from Aerial 2007

Layer Integration

Integrate Sewer Area, HUC 11, Water Purveyor, Open Space, Preserved Farms

Working Draft Model Builder ApplicationSewer Area Selection and Environmental Features removed from

Remaining Lots

Examples of Environmental features removed

Wetlands, Surface Water, Open Space, Preserved Farms, Stream Buffers

• Nitrate dilution density values are calculated by a separate model (A Recharge-Based HUC11-Scale Nitrate – Carrying- Capacity Planning Tool for New Jersey, v1.0 (MS Excel Workbook) andjoined to the HUC 11 shape file.

Other methods to determine septic densitycould be considered by County and Municipality.

Septic Area ExtentWorking Draft Model Builder Application

• Allowable uses and development standards are not considered, these could include but are not limited to:

a) Minimum width and depth per lot b) Lot set backs c) Allowable building stories d) Road access defining building densities “land locked lot”e) Road right of ways not removed f) Percolation limits

• Urban 2002 is used, missing 6 years of development, not measuring re-development areas or existing development expansions. Also, does not measure existing urban on septic within sewer service areas.

• Population estimates not included, application represents all time or absolute build out (No time steps analyzed).

• Urban foot print does not remove the complete associated Minimum Lot Area, in some areas, this over estimates by 1 new unit in oversized lots.

Application Method Limitations(Updates)

Application Method Limitations

• 100% of selected environmental constraints (Wetlands, Stream Corridors & Open Space) are removed from sewer area, some flexibility related to buffer permitting requirements are not recognized.

• Water Purveyor Future Allocation Agreements and Stressed Ecological Flows are not measured in this analysis.

• Does not measure other specific regional zone requirements; 1) Highlands, 2) Pinelands, 3) Delaware River, 4) Meadowlands, 5) CAFRA, etc.

• HUC 11 analysis does not recognize other land use regulated features (ie. stream corridors) which may further restrict land use within specific Septic locations.

Application Method Limitations• HUC 11 Nitrate Dilution Analysis measures only densities for future

septic systems. Additional areas potentially providing dilution not recognized in the sewer areas.

• Contaminated sites not recognized by this application.

• Grandfathering, non-conforming (under Minimum Lot Size) lots are currently not recognized by this application.

• Overlay zones are not recognized by this application.

• Lot ownership current and future plans are not recognized by this application including but not limited to property owners’ and homeowners’ association common area, right of ways, easements, lot consolidation, etc.

• Specific municipal land use variances are not recognized by thisapplication.

Oversize Parcel Over Estimation

• Issue 1 - Urban foot print does not remove the complete associated Minimum Lot Area, in some areas, this over estimates by 1 new unit in oversized lots.

• Potential Fix – “If – Then; Else Statement” within the Access Database

If – Then; Else Statement Logic

1) Determine difference between the Original Parcel Area and the New Area (after Urban foot print removed).

2) “If” the area Difference is > = the Minimum Lot Size; “Then” use the New Area; “Else” use Original Parcel Area minus (-) Minimum Lot Size.

Simple Example

Original Area (Acres) New Area

Difference (Original - New) Minimum Lot Size

Final Size

NewUnits

23 20 3 10 13 1.3

23 20 3 2 20 10

IIf([Difference]>=sewer.MIN_LOT_SI,sewer.F_AREA,sewer.CACRES*43560-sewer.MIN_LOT

Access If – Then; Else Code Statement:

FINAL AREA:

Access Data Base Results

Original New Difference MinLot Final Size New_units

23 20 3 10 13 1.3

23 20 3 2 20 10

200 100 100 10 100 10

200 100 100 2 100 50

200 100 100 50 100 2

200 100 100 100 100 1

200 150 50 25 150 6

30 17 13 10 17 1.7

30 17 13 15 15 1

30 17 13 20 10 0.5

30 17 13 5 17 3.4

Access If – Than, Else Query Test Results

Access Data Base – Query Properties

- Set Unique Values to Yes, to eliminate duplicate records

• Issue 2 - Grandfathering, non-conforming (under Minimum Lot Size) lots are currently not recognized by this application.

• Potential Fix – Undersize Parcel Module

- Select parcels < Minimum lot size and remove urban and some environmental features.

Draft Wastewater Estimator Work

Wastewater Calculations

Sewer Service Area:

1) New Residential = Remaining Area * Zone Density* 300 gallon/unit/day

2) New Non Residential = Remaining Area * FAR * 0.1gal/sqft/day

Septic Area (Compare Existing Zoning to HUC 11 Nitrate Dilution Densities):

1) HUC 11 Nitrate Dilution Calculate New Units (With/ without Open Space)

a) New Residential Units

b) New Non - Residential (FAR)

Both (a) & (b) = Total Area/ HUC 11 Densities

2) Existing Zoning Calculate New Units

a) New Residential Units = Remaining Area * Zone Density

b) New Non - Residential Eq. Calculation = FAR * 0.125 Gal/ Sq. Ft./ Day500 Gal/ Unit/ Day

Branchburg Township, Somerset County –DRAFT Wastewater Flow Estimations for New Residential

Non – residential in Sewer Area

Estimated Wastewater Flows

New Residential = 109 Units

New Residential Wastewater Flow = 32,925 GPD

New Non – Residential = 1,262,560 Square feet

New Non – Residential Wastewater Flow = 126,256 GPD

Total Estimated New Wastewater Flow = 0.159 MGD

Wastewater Calculations – Somerset Raritan Valley SA – NJPDES NJ0024864

Note: Compare Total Estimated Wastewater Flow of the 15 Municipalities to Somerset Raritan Valley SA – NJPDES NJ0024864 Permit

(MGD) (MGD) (MGD)

Somerset Raritan Valley SA – NJPDES NJ0024864 –DMR Existing Wastewater Flow - Data Miner View

Branchburg Township, Somerset County – Estimations of New Units in Septic Area Based On Existing Zoning

Total New Unit Estimates based on Zoning

HUC 11

1) 02030105040 = 122 New units

2) 02030105050 = 14 New units

3) 02030105070 = 207 New units

Branchburg Township, Somerset County – Example of Estimations of New Units in Septic Area Based On HUC 11 Nitrate Dilution Densities Analysis

Total New Unit Estimates based on Nitrate Dilution Densities

HUC 11

1) 02030105040 = 87 New units

2) 02030105050 = 24 New units

3) 02030105070 = 56 New units

Estimated New Units in Septic – Nitrate Dilution Analysis and Zoning Comparison

Water Supply Demand

• WQMP - NJAC 7:15 – 5.25 (f) – Evaluation criteria for wastewater plans and amendments

- Safe Drinking Act – NJAC 7:10 -11.5 (f)

1) Residential Development - DCA Residential Site Improvement Standards (RSIS) at NJAC 5:21 – 5.2, Table 5.1 “Water Demand/Generation by Type/ Size of Housing”

2) Non – Residential Development – at NJAC 7:10 – 12.6 (b)2,Table 1

Residential - Table 5.1 “Water Demand/ Generation by Type/ Size of Housing”

Non – Residential – at NJAC 7:10 – 12.6 (b)2,Table 1

Branchburg Township, Somerset County –DRAFT Water Flow Estimations for New Residential

Non – residential in Sewer Area

Estimated Water Flows

New Residential = 109 Units

New Residential Water Flow = 35,121 GPD

New Non – Residential = 1,262,560 Square feet

New Non – Residential Water Flow = 157,820 GPD

Total Estimated Water Flow = 0.193 MGD

Estimated New Units in Septic – Nitrate Dilution Analysis and Zoning Comparisonwith New Water Demand

Public Water System Deficit/ Surplus

Branchburg Twp., Somerset - New Water Supply DemandElizabethtown Water Company - PWSID 2004002

Sewer New Water Flow = 0.193 MGD Septic New Water Flow = 0.053 MGD

Total Water Flow = 0.246 MGD

Outside Water Purveyor Area compare HUC 11 Water Demand to Water Supply Plan.

• Finalize Branchburg Twp. Wastewater Estimation work to fit the County Wastewater Management Template

• Further refinement of the Model Builder Application with more up to date local digital data or database records.

• Coordinate land use planning issues with DEP planners and sustainable community experts.

• Coordinate Quality Control of the process with Counties/ Municipalities at both GIS data level and the Access database level.

Next Steps