DRAINAGE REPORT - City of East Orange

TABLE OF CONTENTS

Page No.

I. Summary………………………………………………….…….….1

II. Runoff Rate Reductions Performance……………………….......2

III. Proposed Water System…………………………………………...2

IV. Proposed Sanitary Sewer System………………………….……...3

V. Conclusion…………………………………………………….…...4

APPENDIX

• NRCS Web Soil Survey

• Runoff Curve Number (CN) Calculations – Existing

• Runoff Curve Number (CN) Calculations – Proposed

• Hydrograph Summary Reports – Existing and Proposed Conditions 2 yr. & 10 yr.

• Hydrograph Summary Reports – Existing and Proposed Conditions 100 yr.

• Stormwater Collection System Calculations

• Drainage Area Maps

• Surface infiltration Testing Report (By Dynamic Earth, LLC) (Under separate cover)

• Capacity of Circular Pipe Flowing ½ Full

KSH N. Oraton Development, LLC - 1 - December 2020

DEC# 3421-99-001 Last Revised February 2021

I. Summary This Drainage Statement & Water and Sanitary Sewer Engineer’s Report has been prepared to define

and analyze the stormwater drainage conditions as well as the water and sewer utility connections

that would occur as a result of the redevelopment of Block 243, Lot 1 as shown on the City of East

Orange Tax Map Sheet No. 24, located in the City of East Orange, Essex County, New Jersey. The

subject site consists of 0.305 acres (13,296 SF) and is located on North Oraton Parkway and Freeway

Drive East.

Under existing conditions, the site is undeveloped with gravel and surface vegetation. The proposed

project consists of developing the property with a 5-story multi-family apartment building with parking

provided beneath the ground floor. Additional site improvements will include lighting, landscaping,

grading, driveways, and other associated site amenities. The new development proposes to reduce the

impervious coverage on site by approximately 13.1% (1,737 SF).

The project consists of less than one (1) acre of disturbance and will not increase the impervious

coverage on-site by ¼ acre or more. Therefore, the proposed project does not meet the definition of a

‘major development’ and is not subject to the NJDEP Stormwater Management Rules (NJAC 7:8).

Furthermore, the proposed development does not increase the existing impervious surfaces on site;

therefore, it is not subject to the New Jersey Standards for Soil Erosion and Sediment Control runoff

rate reduction requirements.

The stormwater runoff is drains via sheet flow to the north of the property towards Route 280 and the

existing stormwater conveyance system located within the intersection of Route 280 and North Oraton

Parkway. Please reference the enclosed Boundary and Topographic Survey, prepared by Dynamic

Survey, LLC, dated 04/29/2020, last revised 10/27/2020, indicating the existing conditions of the

site for additional information.

For the stormwater analysis, the existing gravel surfaces onsite were modeled as impervious surfaces

in accordance with the NJDEP based on the surface infiltration testing and field study that was

conducted. Please refer to the Surface Infiltration Testing Report, prepared by Dynamic Earth, LLC,

dated November 13, 2020 for reference.



The stormwater drainage for the proposed site has been designed to maintain existing runoff patterns

as feasible. The proposed roof leader system routes stormwater from the roof of the proposed building

to the proposed inlets located within the parking lot. The stormwater within the parking lot and

subterranean parking area will be collected by the proposed trench drains and inlets that will be

ultimately drain into the existing stormwater conveyance system within Freeway Drive East.

Stormwater runoff from the landscaped areas on the remainder of the site will drain via sheet flow

towards the north of the site.

II. Runoff Rate Reduction Performance

As noted above, a majority of the stormwater runoff from the proposed development discharges into

the existing stormwater conveyance system located within Freeway Drive East. Due to the

improvements associated with the proposed development, the total runoff discharging to this existing

stormwater conveyance system decreases for the two (2), ten (10) and one-hundred (100) year design

storms modeled as 24-hour SCS Type III design storms as compared to existing conditions. Please

refer to the appendix of this report for the hydrography summary reports indicating the same.

Pre-Development and Post Development Peak Runoff Results Summary

for North Oraton Parkway and Freeway Drive East

Design Storm Pre-Development

Conditions

Post-Development

Conditions

Reduction in

Flow

2 Year 0.751 CFS 0.709 CFS 0.042 CFS

10 Year 1.147 CFS 1.105 CFS 0.042 CFS

100 Year 1.910 CFS 1.872 CFS 0.038 CFS

III. Proposed Water System

A 2.5” domestic water service line is proposed to connect to the existing main located long North

Oraton Parkway.

a) DOMESTIC WATER DEMAND CALCULATIONS

In accordance with N.J.A.C. 7:10-12.6(2) 2 – Table 1, the NJDEP standard for the daily

domestic water demand for multiple family dwellings (apartments) is 75 gallons per person.

Estimated domestic water average daily demand can be calculated as follows:



• Multiple family dwelling (28 one-bedroom & 12 two-bedroom units)

o 52 Persons * 75 GPD = 3,900 GPD

• Total Proposed Water Average Daily Demand = 3,900 GPD

IV. Proposed Sanitary Sewer System

A 6” SDR-35 sanitary sewer service lateral is proposed to connect to the existing sanitary sewer main

located within Freeway Drive East via doghouse manhole connection

a) PROPOSED SANITARY SEWER DEMANDS

In accordance with N.J.A.C. 7:14A-23.3(a), the NJDEP standard for the daily sanitary

sewerage flow for the one (1) bedroom units are 150 GPD and two (2) bedroom units are 225

GPD.

Estimated sanitary sewer average daily demand can be calculated as follows:

• One (1) bedroom unit:

o 28 Units* 150 GPD/Unit = 4,200 GPD

• Two (2) bedroom unit:

o 12 Units *225 GPD/Unit = 2,700 GPD

• Total Proposed Sanitary Sewer Demand = 6,900 GPD

b) PROPOSED SANITARY SEWER DESIGN

Per NJDEP regulations, the criteria for establishing the size of sanitary sewer gravity pipes is

to convey two times the average flow with the pipe flowing half full. Utilizing Manning’s

equation with a roughness coefficient of 0.010 for a PVC pipe, the following is the minimum

capacity of the proposed gravity sewer lateral.

Pipe Size Minimum Slope Roughness (n) Capacity at ½ Full 2 X ADF

6” 2.08% 0.010 334,262 GPD 13,800 GPD

The proposed sanitary sewer design can efficiently convey two times the proposed average

daily flow at minimum required pipe slope while flowing half full while utilizing

approximately 4.1% of the line’s total capacity.



V. Conclusion

The proposed project has been designed to ensure safe and efficient control of the stormwater runoff

in a manner that will not adversely impact the existing drainage patterns and systems, adjacent

roadways, or adjacent parcels. Furthermore, the project decreases the impervious coverage on-site and

thereby does not increase the peak stormwater runoff rates from the parcel. In addition, this report has

been prepared to further expand on the water and sanitary sewer designs for the proposed development

as shown within the accompanying site plan drawings. The water and sanitary sewer demand

generated from this development will not exceed the approved demands and allocated flows based on

the actual usages. We anticipate that the proposed development will not significantly impact the

existing drainage & utility infrastructure located within North Oraton Parkway, Freeway Drive East,

and Route 280.

APPENDIX

NRCS WEB SOIL SURVEY

Soil Map—Essex County, New Jersey

Natural ResourcesConservation Service

Web Soil SurveyNational Cooperative Soil Survey

5/13/2020Page 1 of 3

4512

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566797 566806 566815 566824 566833 566842 566851

566806 566815 566824 566833 566842 566851

40° 45' 31'' N74

° 1

2' 3

1'' W

40° 45' 31'' N

74° 1

2' 2

8'' W

40° 45' 28'' N

74° 1

2' 3

1'' W

40° 45' 28'' N

74° 1

2' 2

8'' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS840 15 30 60 90

Feet0 5 10 20 30

MetersMap Scale: 1:356 if printed on A portrait (8.5" x 11") sheet.

Soil Map may not be valid at this scale.

MAP LEGEND MAP INFORMATION

Area of Interest (AOI)Area of Interest (AOI)

SoilsSoil Map Unit Polygons

Soil Map Unit Lines

Soil Map Unit Points

Special Point FeaturesBlowout

Borrow Pit

Clay Spot

Closed Depression

Gravel Pit

Gravelly Spot

Landfill

Lava Flow

Marsh or swamp

Mine or Quarry

Miscellaneous Water

Perennial Water

Rock Outcrop

Saline Spot

Sandy Spot

Severely Eroded Spot

Sinkhole

Slide or Slip

Sodic Spot

Spoil Area

Stony Spot

Very Stony Spot

Wet Spot

Other

Special Line Features

Water FeaturesStreams and Canals

TransportationRails

Interstate Highways

US Routes

Major Roads

Local Roads

BackgroundAerial Photography

The soil surveys that comprise your AOI were mapped at 1:12,000.

Warning: Soil Map may not be valid at this scale.

Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale.

Please rely on the bar scale on each map sheet for map measurements.

Source of Map: Natural Resources Conservation ServiceWeb Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857)

Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required.

This product is generated from the USDA-NRCS certified data as of the version date(s) listed below.

Soil Survey Area: Essex County, New JerseySurvey Area Data: Version 15, Sep 16, 2019

Soil map units are labeled (as space allows) for map scales 1:50,000 or larger.

Date(s) aerial images were photographed: Aug 25, 2014—Sep 27, 2014

The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident.




5/13/2020Page 2 of 3

Map Unit Legend

Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI

USBOOB Urban land, Boonton substratum - Boonton complex, red sandstone lowland, 0 to 8 percent slopes

0.3 100.0%

Totals for Area of Interest 0.3 100.0%




5/13/2020Page 3 of 3

RUNOFF CURVE NUMBER (CN) CALCULATIONS

EXISTING

Project: Proposed Multi-Family Apartment Building Computed By: RTO

Job #: 3421-99-001 Checked By: LMS

Location: East Orange, NJ Date:

Drainage Area Impervious

Area (acre)

Impervious

Area (sf)

Curve

Number

(CN) Used

Avg. Perv.

Curve

Number

Total

Pervious

Area

(acres)

Total Area

(acres)

TC (Min.)

NORTH ORATON PARKWAY 0.31 13,296 98 N/A N/A 0.31 10

Total 0.31 13296.00 0.00 0.31

USBOOB HSG D Soil Urban

DescriptionImpervious Surface 98

Gravel 91Open Space (lawn) (good) 80

Woods (good) 77

12/1/2020

Runoff Curve Number (CN) (HSG

D)

Per County Soil Survey -

RUNOFF CURVE NUMBER (CN) CALCULATIONS

PROPOSED

Project: Proposed Multi-Family Apartment Building Computed By: RTO

Job #: 3421-99-001 Checked By: JEH

Location: East Orange, NJ Date:

Drainage Area Impervious

Area (acre)

Impervious

Area (sf)

Curve

Number

(CN) Used

HSG D -

Open

Space Area

(acre)

HSG D -

Open

Space Area

(sf)

Curve

Number

(CN) Used

Avg. Perv.

Curve

Number

Total

Pervious

Area

(acres)

Total Area

(acres)

TC (Min.)

NORTH ORATON PARKWAY 0.27 11,559 98 0.04 1,737 80 80 0.04 0.31 10

Total 0.27 11559.00 0.04 1737.00 0.04 0.31

USBOOB HSG D Soil Urban

DescriptionImpervious Surface 98

Gravel 91Open Space (lawn) (good) 80

2/17/2021

Runoff Curve Number (CN) (HSG

D)

Per County Soil Survey -

HYDROGRAPH SUMMARY REPORTS

EXISTING AND PROPOSED CONDITIONS

2YR & 10YR

HYDROGRAPH SUMMARY REPORTS

EXISTING AND PROPOSED CONDITIONS

100YR

STORMWATER COLLECTION SYSTEM

CALCULATIONS

NOTES:Project: Proposed Mult-Family Apartment Building Computed By: ACC 1) Design method used is Rational Method, unless otherwise noted.Job #: 3421-99-001 Checked By: RTO 2) Refer to Weighted Runoff Coefficient table

Location: East Orange Date: 11/30/2020 for calculation of incremental areas and C valuesDesign Storm: 25 YR

SUBCATCHMENT AREA

CUMULATIVE I PIPING INPUT PIPING DATA

FROM TO Area (Acres) "C" A x C Ac A x C (acres)Tc to Inlet (min)

Tc in Pipe

(min.)

Final Tc (min)

(In/Hr)Q to Inlet

(CFS)

Q cum. for Pipe (CFS)

Dia. (In)

Length (Ft)

Man. "n"

Slope (ft/ft)

Pipe Capacity

(cfs)

Pipe Velocity

(fps)

Trench Drain 1 Inlet 16 0.01 0.95 0.01 0.01 10 0.19 10 6.80 0.07 0.07 4 32 0.01 0.01 0.25 2.87Trench Drain 2 Inlet 16 0.01 0.95 0.01 0.01 10 0.05 10 6.80 0.07 0.07 4 9 0.01 0.01 0.25 2.87Trench Drain 3 Inlet 16 0.01 0.95 0.01 0.01 10 0.21 10 6.80 0.07 0.07 4 36 0.01 0.01 0.25 2.87Roof Leader 1 Inlet 16 0.08 0.95 0.08 0.08 10 0.1 10 6.80 0.54 0.54 6 23 0.01 0.01 0.73 3.72Roof Leader 2 Inlet 16 0.08 0.95 0.08 0.08 10 0.1 10 6.80 0.54 0.54 6 23 0.01 0.01 0.73 3.72Roof Leader 3 Inlet 16 0.08 0.95 0.08 0.08 10 0.22 10 6.80 0.54 0.54 6 50 0.01 0.01 0.73 3.72

Inlet 16 Inlet 17 0.07 0.95 0.07 0.34 10 0.26 10.22 6.80 0.48 2.31 15 58 0.013 0.005 4.57 3.73Trench Drain 4 Inlet 17 0.01 0.95 0.01 0.01 10 0.29 10 6.80 0.07 0.07 4 50 0.01 0.01 0.25 2.87Trench Drain 5 Inlet 17 0.01 0.95 0.01 0.01 10 0.18 10 6.80 0.07 0.07 4 31 0.01 0.01 0.25 2.87

Inlet 17 Inlet 18 0.07 0.95 0.07 0.43 10 0.21 10.48 6.80 0.48 2.92 15 46 0.013 0.005 4.57 3.73Inlet 18 Manhole 10 0.01 0.95 0.01 0.44 10 0.16 10.69 6.68 0.07 2.94 15 36 0.013 0.005 4.57 3.73

PIPE SECTION INCREMENTALTIME OF

CONCENTRATIONPEAK RUNOFF

DRAINAGE AREA MAPS

ã

1904 Main StreetLake Como, NJ 07719

T: 732.974.0198F: 732.974.3521

www.dynamicec.com

LAND DEVELOPMENT CONSULTING ● PERMITTING ● GEOTECHNICAL ● ENVIRONMENTAL ● SURVEY ● PLANNING & ZONINGOffices conveniently located in:

Lake Como, New Jersey T: 732.974.0198 | Chester, New Jersey T: 908.879.9229 | Newark, New Jersey T: 973.755.7200 | Toms River, New Jersey T: 732.974.0198Allen, Texas T: 972.534.2100 | Austin, Texas T:512.646.2646 | Houston, Texas T: 281.789.6400

Newtown, Pennsylvania T: 267.685.0276 | Delray Beach, Florida T: 561.921.8570

JAMES E. HENRYJOSHUA M. SEWALD

UP

ã

1904 Main StreetLake Como, NJ 07719

T: 732.974.0198F: 732.974.3521

www.dynamicec.com

LAND DEVELOPMENT CONSULTING ● PERMITTING ● GEOTECHNICAL ● ENVIRONMENTAL ● SURVEY ● PLANNING & ZONINGOffices conveniently located in:

Lake Como, New Jersey T: 732.974.0198 | Chester, New Jersey T: 908.879.9229 | Newark, New Jersey T: 973.755.7200 | Toms River, New Jersey T: 732.974.0198Allen, Texas T: 972.534.2100 | Austin, Texas T:512.646.2646 | Houston, Texas T: 281.789.6400

Newtown, Pennsylvania T: 267.685.0276 | Delray Beach, Florida T: 561.921.8570

JAMES E. HENRYJOSHUA M. SEWALD

SURFACE INFILTRATION REPORT

(BY DYNAMIC EARTH, LLC)

(UNDER SEPARATE COVER)

CAPACITY OF CIRCULAR PIPE FLOWING ½ FULL

Project: Parkway Commons Computed By: AC

Job #: 3421-99-001 Checked By: RTO

Location: City of East Orange, Essex County, NJ Date: 2/15/2021

PIPE DESCRIPTION SLOPE SIZE MANNING'S VELOCITY CAPACITY CAPACITY CAPACITY

(%) (IN) COEFFICIENT (FT/S) (CFS) (GPD) (MGD)

(n)

Prop. 6" Lateral 2.080% 6 0.010 5.27 0.52 334,262 0.33

Variables Defined Typical Values for Manning's Coefficient (n)

Q=Capacity of Pipe (CFS) n(RCP)= 0.013

V=Velocity in Pipe Section (FT/S) n(HDPE-Smooth Interior)= 0.012 *Varies with Manufacturer

R=Hydraulic Radius of Pipe Section n(DIP)= 0.013

S=Slope of Pipe Section (FT/FT) n(PVC)= 0.010

D=Diameter of Pipe (FT) n(CMP)= 0.024

d=Depth of Flow in Pipe (FT)

n=Manning's Coefficient

Wp=Wetted Perimeter (FT)

Equations used:

Q=VA

V=(1.49/n)*R^(2/3)*S^(1/2)

Q=(1.49/n)*R^(2/3)*S^(1/2)*A

Utilizing Appendix 16.A from the Civil Engineering Reference Manual-Seventh Edition, by Micheal Lindeburg, Copyright 1999

The following equations were utilized to calculate the Hydraulic Radius and Area of a Circular Pipe Section flowing 1/2 full

A=(π*D^2/4)*0.5=0.3927*D^2

R=A/Wp=0.3927*D^2/((2*π*D/2)*0.5)=0.25*D

Therefore:

Q=(1.49/n)*(0.25*D)^(2/3)*S^(1/2)*(0.3927*D^2)

V=(1.49/n)*(0.25*D)^(2/3)*S^(1/2)

Unit Conversion Equations

1 Cubic Foot=7.4805 Gallons

1 Day = 86,400 Seconds

Therefore:

Cubic Foot 86,400 Seconds 7.4805 Gallons Gallon

Second 1 Day 1 Cubic Foot Day

Gallon 1 Million Gallons Million Gallons

Day 1,000,000 Gallons Day

=X X

X =

DRAINAGE REPORT - City of East Orange

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