stormwater management report-2

PACE UNIVERSITY

PLEASANTVILLE CAMPUS

TOWN OF MOUNT PLEASANT, NEW YORK

STORMWATER MANAGEMENT REPORT

Prepared for:

PACE UNIVERSITY

Mount Pleasant, New York

Prepared By:

DIVNEY TUNG SCHWALBE, LLP

One North Broadway, Suite 1407

White Plains, New York 10601

December 2011

PACE UNIVERSITY PLEASANTVILLE CAMPUS

MOUNT PLEASANT, NEW YORK


TABLE OF CONTENTS PAGE NO. I. EXECUTIVE SUMMARY .............................................................................................I-1 II. BACKGROUND ............................................................................................................II-1 A. Site Location ............................................................................................................II-1 B. Purpose and Objective ..............................................................................................II-1 C. Site Characteristics and Drainage Summary ..............................................................II-1 1. Site Characteristics ............................................................................................II-1 2. Existing Conditions ...........................................................................................II-2 3. Proposed Conditions .........................................................................................II-7 III. STORMWATER QUANTITY .......................................................................................III-1 A. Existing Conditions ..................................................................................................III-1 B. Developed Conditions ..............................................................................................III-1 C. Proposed Stormwater Management ..........................................................................III-1 D. Runoff Reduction .....................................................................................................III-3 E. Flood Zones .............................................................................................................III-7 IV. STORMWATER QUALITY ..........................................................................................IV-1 A. Stormwater Quality Analysis ....................................................................................IV-1 1. Existing Conditions ...........................................................................................IV-1 2. Post-Development Conditions Without Treatment ...........................................IV-1 3. Post-Development Conditions With Treatment ................................................IV-1 B. Stormwater Quality Management Measures .............................................................IV-1 1. Wet Extended Detention Pond ..........................................................................IV-6 2. Rain Garden / Bioretention Filters ....................................................................IV-8 3. Porous Pavement ...............................................................................................IV-8 4. Open Channels ..................................................................................................IV-8 5. Catch Basin Sumps ............................................................................................IV-8 6. Stormwater Pollution Prevention Plan ..............................................................IV-9




V. TECHNICAL APPENDIX .....................................................................................V-1

A. Methodology .....................................................................................................V-1 1. Zero Increase in Watershed Peak Runoff ..................................................V-1 2. Storm Frequencies......................................................................................V-1

3. Technical Approach ....................................................................................V-1 4. Soil Classifications ......................................................................................V-2 5. Detention Requirements ............................................................................V-2 6. Rainfall Intensity ........................................................................................V-2

B. Calculations .......................................................................................................V-3 1. Curve Numbers ..........................................................................................V-3 2. Times of Concentration and Travel Times ..................................................V-3 3. Pipe Sizing .................................................................................................V-3 4. Channel Protection Volume .......................................................................V-4 5. Water Quality Volume ...............................................................................V-4

C. Pond Pack Modeling 1. Existing Conditions ....................................................................................V-C-1 2. Proposed Conditions ..................................................................................V-C-2




LIST OF TABLES TABLE PAGE No. NO. 1 Existing Drainage Conditions ............................................................................... II-5 2 Proposed Drainage Conditions ............................................................................. II-10 3 Design Flow Summary ......................................................................................... III-2 4 DEC List of Approved Stormwater Measures – Green Infrastructure ................... III-4 5 DEC List of Approved Stormwater Measures – Standards Management Practices IV-2 6 Water Quality Volume and Runoff Reduction Volume Calculations ................... IV-7 7 Existing Conditions Curve Number Calculations ................................................. V-5 8 Proposed Conditions Curve Number Calculations ............................................... V-6 9 Existing Time of Concentration ........................................................................... V-7 10 Proposed Time of Concentration ......................................................................... V-8

LIST OF FIGURES FIGURE PAGE No. NO. 1 Overall Site Plan ................................................................................................... I-3 2 Existing Soils Map ................................................................................................ II-3 3 Existing Drainage Conditions ............................................................................... II-4 4 Developed Drainage Conditions ........................................................................... II-9

I - 1

I. EXECUTIVE SUMMARY

In support of the Pace University Master Plan Update, this Stormwater Management

Report evaluates potential changes in stormwater runoff quantity and quality and the

measures proposed to improve the stormwater conditions on the project site in

connection with the redevelopment of the Pleasantville Campus of Pace University.

The approximate 202-acre project site is located in the Town of Mount Pleasant,

Westchester County, New York. Figure No. 1, Master Plan Update presented on the

following page depicts the full build-out project, including all future phases of

development. Under the Master Plan Update it is proposed to construct nine (9) new

buildings and either relocate, renovate or put additions onto six (6) existing structures.

Work consists of the construction of six (6) new Residence Halls, Field House, Theater,

and Welcome Center. Also included is the expansion of the existing student union,

renovations to Martin and North Halls, and relocation of the existing Environmental

Center. The Master Plan Update also includes the demolition of 15 existing building.

There will be new roadways and parking lots associated with the new buildings. The

plan will increase the impervious surfaces within the site by approximately 3.5 acres

from approximately 34.2 acres to 37.7 acres. This increase in impervious area is

expected to cause an associated increase in stormwater peak flow rates and an increase in

nutrient and contaminant loads discharging to surface waters. However, the Proposed

Action also includes plans for the implementation of both structural and non-structural

best management practices to mitigate the potential impacts from development.

Present development of the site provides minimal water quality treatment and detention

of surface water runoff (from either buildings, roads, or parking lots) prior to

conveyance of the runoff to the unnamed stream along the Taconic State Parkway.

Under the Proposed Action, the project’s stormwater quality management objective is to

meet or exceed the requirements set forth in the NYSDEC SPDES General Permit for

I - 2

Stormwater Discharges from Construction Activity (Permit No. GP-0-10-001)

regarding post-development stormwater quantity and stormwater quality.

As such, a combination of Stormwater Management Practices (SMPs) are proposed

herein, including the expansion of an existing stormwater basin and pond, the

installation of new bio-retention basins, and the construction of new pervious pavement

areas to detain and treat the site’s stormwater runoff. The SMPs are designed to treat

the runoff from new buildings and parking lots from 90% of expected rain events, as

defined by the 2010 New York State Stormwater Management Design Manual. The

SMPs will also provide detention for storm events up to and including the 100-year

storm.

II - 1

II. BACKGROUND

A. SITE LOCATION

The approximate 202-acre project site is located in the Town of Mount Pleasant,

Westchester County, New York. The site is located to the east of the Taconic State

Parkway, to the north of New York State Route 117 (Bedford Road), to the west of

Choate Lane, and to the south of Pleasantville Road. Briarcliff High School is located to

the northwest of the campus.

B. PURPOSE AND OBJECTIVE

The purpose of this report is to evaluate the stormwater management requirements of the

proposed site plan. The report quantifies stormwater runoff on the site for both existing

and post-development conditions.

The project’s stormwater quality management objective is to improve the quality of

stormwater runoff from the on-site redevelopment areas as well as to manage the

stormwater quantity and quality of runoff in the areas of new construction, all in

accordance with the requirements set forth in the NYSDEC SPDES General Permit for

Stormwater Discharges from Construction Activity (Permit No. GP-0-10-001).

C. SITE CHARACTERISTICS AND DRAINAGE SUMMARY

1. Site Characteristics

The project area is generally limited to the existing campus development area. The

developed area consists of buildings, driveways, parking lots, and lawn areas. Outside

of the developed portions of the campus, the site is mostly wooded. The U.S.

Department of Agriculture Soil Conservation Service has classified soil types as shown

II - 2

on Figure No. 2, Existing Soils Map.

2. Existing Conditions

The existing conditions of the campus are shown on Figure No. 3, Existing Drainage

Conditions along with the existing drainage patterns. Development of the campus is

generally comprised of residence halls, academic buildings, a library, athletic fields,

sports and recreation facilities, utility infrastructure systems and appurtenances, and

associated parking facilities. The subject site contains sloping land that drops from a

high point elevation of approximately 580 feet (above average sea level) in the east

central quadrant of the site to an elevation of approximately 240 feet along the stream

leaving the western edge of the site in the area adjacent to the Taconic State Parkway

(Taconic) northbound lanes. Though approximately 70 acres of the site drains

through Choate Pond, located in the center of the campus development, it too

discharges to the stream system located along the Taconic. In total, runoff from

approximately 150 acres of the developed site discharges ultimately to the Pocantico

River via the existing stream system adjacent to the Taconic. Further, this 150-acre

portion of the site contains the majority of development on the site. The remaining

approximate 52 acres of the site is, with a minor exception, undeveloped and drains

toward Choate Lane, Pleasantville Road, and Briarcliff High School and ultimately

tributary to the Saw Mill River. The site contains USACOE, NYSDEC, and locally

regulated wetlands. Presented below is a more detailed description of the individual

watershed areas which comprise the project site.

The project area has been divided into eight (8) watershed sub-basins for evaluation

within this report. The drainage characteristics of each of the existing sub-basins are

shown on Table No. 1, Existing Drainage Conditions, and described below.

TABLE NO. 1

PACE UNIVERSITY

PLEASANTVILLE, NEW YORK

EXISTING DRAINAGE CONDITIONS

(1) (2) (3) (4)

I Rv CN Ia Tc

Roof Pavement IMP. TOTAL (%) (HRS)

A 2.63 6.14 8.77 41.71 50.48 17.37 0.21 67 1.0 0.28 1

B 3.00 10.88 13.88 40.51 54.39 25.52 0.28 69 0.9 0.26 1

C 0.00 1.30 1.30 14.22 15.52 8.38 0.20 64 1.1 0.23 1

D 0.12 1.88 2.00 5.98 7.98 25.06 0.28 71 0.8 0.16 1

E 0.60 1.95 2.55 0.78 3.33 76.58 0.74 92 0.2 0.15 1

F 0.02 2.31 2.33 2.09 4.42 52.71 0.52 82 0.4 0.08 1

G 0.63 2.27 2.90 2.05 4.95 58.59 0.58 82 0.4 0.16 1

H 0.00 0.46 0.46 2.35 2.81 16.37 0.20 67 1.0 0.00 2

TOTAL AREA 7.00 27.19 34.19 109.69 143.88 69

1. I=Percent Impervious, (Impervious Area/Total Area)*100%

2. Rv = 0.05+0.009(I), Minimum Rv=0.2

3. CN=Curve Number

4. Tc=Time of Concentration, Tt=Travel Time

DESIGN

POINT

#

AREA (AC)

IMPERVIOUSWATERSHED/

SUBBASIN ID TOTAL

AREAPERVIOUS

728 Stormwater Analysis GP-0-10-001 Updated.xls 12/21/2011 Divney Tung Schwalbe, LLP

II - 6

Sub-Basin A – This sub-basin is located in the north central portion of the

development and includes the existing Townhouse residence halls, the Administration

Center, and Goldstein Fitness Center. The sub-basin drains through an on-site stream

to the off-site stream along the Taconic State Parkway.

Sub-Basin B – This sub-basin is located in the central portion of campus and includes

Martin Hall, Kessel Student Center, Mortola Library, North Hall, Goldstein Academic

Center, Paton House, Environmental Center, Wilcox Hall, Entry Drives 2 and 3, and

Choate Pond. Though runoff within the basin drains to Choate Pond, the pond’s

outflow discharges through a series of pipes and open streams located in Sub-basin F

to the off-site stream along the Taconic State Parkway.

Sub-Basin C – This sub-basin is located in eastern portion of the development. The

sub-basin is mostly undeveloped but includes two parking lots, a basketball court and a

beach volleyball court. In addition, there is a depression adjacent to the largest

parking areas that forms a wetland and allows limited ponding with the sub-basin.

Runoff from this sub-basin is conveyed to Choate Pond located within sub-basin B.

Sub-Basin D – This sub-basin is located in the western portion of the campus and

includes the football field, field house, and student/athletic facility parking areas. The

sub-basin drains to the off-site stream along the Taconic State Parkway.

Sub-Basin E – This sub-basin is located in the western portion of the campus and

includes part of Lienhard and Miller Hall, as well as parking areas. The sub-basin

drains to the off-site stream along the Taconic State Parkway.

Sub-Basin F – This sub-basin is located in the southwestern portion of the campus and

includes the tennis courts, a parking lot and the on-site portion of the stream that

conveys the outflow from Choate Pond to the off-site stream along the Taconic State

Parkway.

II - 7

Sub-Basin G – This sub-basin is located in the southern portion of the campus along

Bedford Road and includes Dyson Hall, the Costello House, associated parking areas,

and a portion of the Entry 1 access drive. The sub-basin drains to the off-site stream

along the Taconic State Parkway.

Sub-Basin H – This sub-basin is located in the southwestern portion of the campus

and includes all three (3) campus entrances and the former 901 Bedford Road

property. The sub-basin drains to the Bedford Road.

Design Point – The design point for the analyses contained herein is the off-site stream

adjacent to the northwest corner of the property and is shown on Figure No. 3.

3. Proposed Conditions

The Pace University Master Plan Update involves the redevelopment of the existing

Pleasantville Campus. Under the Master Plan Update it is proposed to construct nine

(9) new buildings and either relocate, renovate or put additions onto six (6) existing

structures. Work consists of the construction of six (6) new Residence Halls, Field

House, Theater, and Welcome Center. Also included is the expansion of the existing

student union, renovations to Martin and North Halls, and relocation of the existing

Environmental Center. The Master Plan Update also includes the demolition of 15

existing building. There will be new roadways and parking lots associated with the

new buildings. The Master Plan Update will provide additional student residences and

facilities for the University while improving the on-site campus circulation, enhancing

the on-site natural features, and the allow for the implementation of a stormwater

management plan. The planning techniques incorporated into the Master Plan Update

include:

• Preservation of Undisturbed Areas

II - 8

• Preservation of Buffers

• Reduction of Clearing and Grading

• Locating Development in Less Sensitive Areas

• Open Space Design

• Soil Restoration

• Roadway Reduction

• Driveway Reduction

• Building Footprint Reduction

Post-development site conditions are shown on Figure No. 4, Proposed Drainage

Conditions. The amount of impervious area will increase by approximately 3.5 acres,

from 34.2 to 37.7 acres. The eight (8) existing sub-basins identified in Section 2,

Existing Conditions have been further divided into 11 sub-basins for the purposes of

evaluation and sizing of proposed stormwater treatment measures. The drainage

characteristics of each of the sub-basins are shown on Table No. 2, Developed

Drainage Conditions, and described briefly below.

Sub-Basin AA-1 – This Sub-Basin located on the northwestern portion of the site will

remain mostly unchanged, with the exception of the baseball field which will have its

natural grass field replaced with an artificial turf material complete with an integral

underdrain system.

Sub-Basin AA-2 – This Sub-Basin located on the northern portion of the site will have

three (3) existing residence halls removed and three (3) new residence halls

constructed. There will also be an expansion of the northerly most parking areas, and

the Environmental Center will be re-located to southerly end of this sub-basin,

adjacent to the Paton House. Runoff from this sub-basin will be routed to an

expanded wet extended detention pond located north of the Goldstein Fitness Center.

TABLE NO. 2

PACE UNIVERSITY


DEVELOPED DRAINAGE CONDITIONS

(1) (2) (3) (4)

I Rv CN Ia Tc

Roof Pavement IMP. TOTAL (%) (HRS)

AA-1 0.01 0.31 0.32 15.07 15.39 2.08 0.20 62 1.2 0.28 1

AA-2 2.57 5.59 8.16 25.23 33.39 24.44 0.27 69 0.9 0.28 1

BB1 3.46 7.27 10.73 18.07 28.80 37.26 0.39 74 0.7 0.26 1

BB2 1.35 3.85 5.20 17.64 22.84 22.77 0.25 67 1.0 0.00 1

BB3 0.83 1.88 2.71 2.61 5.32 50.94 0.51 79 0.5 0.00 1

CC 0.00 1.43 1.43 14.09 15.52 9.21 0.20 64 1.1 0.23 1

DD 0.37 2.15 2.52 5.44 7.96 31.66 0.33 73 0.7 0.16 1

EE 0.39 1.64 2.03 0.96 2.99 67.89 0.66 90 0.2 0.15 1

FF 0.03 2.08 2.11 2.11 4.22 50.00 0.50 82 0.5 0.08 1

GG 0.53 1.68 2.21 2.43 4.64 47.63 0.48 78 0.5 0.08 1

HH 0.00 0.28 0.28 2.53 2.81 9.96 0.20 65 1.1 0.08 2

TOTAL AREA 9.54 28.16 37.70 106.18 143.88 70

1. I=Percent Impervious, (Impervious Area/Total Area)*100%

2. Rv = 0.05+0.009(I), Minimum Rv=0.2

3. CN=Curve Number

4. Tc=Time of Concentration, Tt=Travel Time

WATERSHED/

SUBBASIN ID

DESIGN

POINT

#

AREA (AC)

IMPERVIOUS TOTAL

AREAPERVIOUS


II - 11

Sub-Basin BB-1 – This Sub-Basin located in center core of the campus will have three

(3) new residence halls, a new theater/academic building and an addition to the

existing student union. The road and walkway system will be revised to improve

vehicle and pedestrian circulation. Choate Pond will be enhanced through forebays,

bank stabilization and improvements, possible dredging. Stormwater runoff from the

new buildings will be directed to grass infiltration areas, bioretention basins, porous

pavement, and vegetated swales. All runoff from this sub-basin, as well as sub-basin

BB-2, BB-3 and CC outlined below, drains to Choate Pond.

Sub-Basin BB-2 – This Sub-Basin located east of Choate Pond includes Martin and

North Halls and a portion of new Residence Hall C. The runoff from this sub-basin

drains to an existing wetland just south of new Residence Hall B before entering

Choate Pond. Bioretention basins will be used to treat the runoff from the new

buildings, and the wetland and watercourse will be enhanced by day-lighting a

segment closest to Choate Pond. Porous pavement will also be used in the new

parking area to be constructed adjacent to new Residence Hall B. Runoff from sub-

basin CC will also drain through the wetland located within this sub-basin.

Sub-Basin BB-3 – This Sub-Basin located in the southern portion of the site will have

a new administrative building, welcome center and parking lot. Stormwater runoff

from the sub-basin will be directed to a bioretention basin before draining to Choate

Pond.

Sub-Basin CC – This Sub-Basin is mostly unchanged from existing conditions, with

the exception of the construction of a new parking lot in the area of the existing

basketball and beach volleyball courts.

Sub-Basin DD – This Sub-Basin located on the western portion of the site will have

the existing grass football replaced with an artificial turf field and recreational track.

Additionally there will be a new Field House, bleachers, and expansion and

II - 12

modifications to the existing parking lot at the top of the hill behind the existing

Choate House. The stormwater measures in this sub-basin will include porous

pavement, bioretention areas, vegetated swale, and an underdrain/infiltration system

for the turf field.

Sub-Basin EE – This Sub-Basin will remain unchanged, with the minor exception of

the addition of a small bioretention area adjacent to the new Field House.

Sub-Basin FF – This Sub-Basin will remain mostly unchanged with the exception of

the addition of one (1) tennis court to the three (3) existing courts.

Sub-Basin GG – This Sub-Basin located in the southwest portion of the site will

include a new parking lot and softball field. The stormwater measures in this sub-

basin will include porous pavement and vegetated swales.

Sub-Basin HH – This Sub-Basin will remain mostly unchanged with the exception of

the revised entrance road at existing Entry 1.

III - 1

III. STORMWATER QUANTITY

A. EXISTING CONDITIONS

Refer to Section II.C.2. for a description of existing conditions.

B. DEVELOPED CONDITIONS

Under proposed conditions, the total volume of runoff from the Project Area is expected

to increase due to an approximate 3.5-acre increase in on-site impervious area. However,

any increase in peak rates of runoff will be mitigated by the use of stormwater basins and

outlet controls on Choate Pond and two (2) on-site wetlands. Stormwater runoff from

developed areas will be directed to the stormwater basins via a combination of

underground piping and surface swales. The outlet controls of the detention systems will

control the rate of release of the detained water such that the peak rate of runoff at each of

the design points is less than or equal to existing runoff rate for up to the 100-year storm

event. A comparison of the pre- and post-development peak runoff rates is shown on

Table No. 3, Design Flow Summary.

C. PROPOSED STORMWATER MANAGEMENT

One objective of a stormwater management plan is to limit the proposed peak rate of off-site

stormwater runoff to levels equal to or less than the existing peak rates of off-site flows.

This will be accomplished by temporarily detaining a portion of the stormwater runoff in

the stormwater basins, Choate Pond, and the wetlands. Orifices are set on the outlet control

structure to detain the 1-year storm for 24 hours, and control the release rate of storms up

to the 100-year storm. An emergency overflow weir is located at the top of each stormwater

basin to safely convey the runoff if it exceeds the capacity of the outlet control structure. See

Table No. 3 for storage volumes associated with various size storm events.

TABLE NO. 3

PACE UNIVERSITY


DESIGN FLOW SUMMARY

SW Flow Runoff Volume SW Flow Runoff Volume SW Flow Runoff Volume SW Flow Runoff Volume SW Flow Runoff Volume

(CFS) (AC-FT) (CFS) (AC-FT) (CFS) (AC-FT) (CFS) (AC-FT) (CFS) (AC-FT)

1 Existing 45.6 7.36 68.5 10.43 149.0 21.34 226.2 32.18 460.2 52.26

Dev w/o SWM 46.7 7.83 69.8 11.02 150.5 22.25 246.1 33.31 490.4 53.69

Developed 31.3 6.70 49.2 9.85 169.5 20.98 280.2 31.97 459.1 52.23

Delta -14.3 -0.66 -19.4 -0.58 20.5 -0.36 54.1 -0.21 -1.1 -0.03

(1) Northeast Regional Climate Data Center

DESIGN

POINT NO.

1-YEAR 2-YEAR

3.0 3.5 5.0 6.3

Westchester

County Rainfall

(IN) (1)8.5

10-YEAR 25-YEAR 100-YEAR


III - 3

D. RUNOFF REDUCTION

As described in the NYSDEC Stormwater Manual (August 2010), runoff reduction is the

reduction of the total Water Quality Volume (WQV) by application of green infrastructure

techniques and Stormwater Management Practices (SMP) to replicate pre-development

hydrology. Table No. 4, DEC List of Approved Stormwater Measures – Green

Infrastructure provides a list of the Green Infrastructure techniques, the design requirements

and recommendations for each technique, and identifies whether or not the practices are

feasible at the project site. The minimum required Runoff Reduction Volume (RRV) is

defined as the Specified Reduction Factor (S), a percentage of the WQV.

The Green Infrastructure Techniques and their feasibility for this phase of the project are

summarized below:

a. Conservation of Natural Areas – While conservations easements are not being

offered, approximately 114 acres of the 200-acre site will remain undeveloped. The

majority of this land is wooded.

b. Sheet Flow to Riparian Buffers or Filter Strips – The 100’ wetland buffers will

generally be maintained on the site, however the steep slopes on the site are not

conducive for directly discharging runoff from impervious areas.

c. Vegetated Swale – Wherever feasible the project has proposed to use open channels.

The open channels will be vegetated swales in areas of low slopes. Approximately

1,700 feet of open channels will be provided.

TABLE NO. 4

PACE UNIVERSITY


DEC LIST OF APPROVED RUNOFF REDUCTION STORMWATER MEASURES

Design Requirements Design Recommendations RR-Volume RR-Area

1. Conservation Area 10,000 sf min. Uses: Forest, stream and river corridors, wetlands, vernal pools N Area &

Contributing

AreaOn-site contribution area of WQV.

Not disturbed during construction

Not managed turf

2. Sheetflow/Filter Strips 150' max contibuting length - pervious N Area &

Contributing

Area75' max contibuting length - impervious

Level spreader req'd for 3% - 15% slope

Min. Width: 50' @ 0-8%, 75' @ 8-12%, 100' @ 12-15%

C soils increase buffer width 15%

D soils increase buffer width 20%

3. Vegetated Swales Drainage area less than 5 acres 20% A & B N

WQV peak flow less than 3 cfs 10% C & D

A and B Soils 20% Runoff Reduction

C and D Soils 10% Runoff Reduction

C (modified) Soils 15% Runoff Reduction

D (modified) Soils 12% Runoff Reduction

100' minimum length

10 minute detention from point source

5 minute detention from sheet flow or multiple points

Velocity less than 1 fps

Depth less than 4 inches

Check Dams as needed

Trapezoid or parabolic shape, bottom width 2' min, 6' max

Max side slope 3:1

Slope between 0.5% and 4%

Convey 10-year storm w/6" freeboard

Practice

728 DEC Approved Stormwater Measures.xlsx - Green Techniques Divney Tung Schwalbe, LLP

Design Requirements Design Recommendations RR-Volume RR-AreaPractice

4. Tree Planting New Trees: N 100 sf

Trees from approved list Min. 1,000 cubic feet of soil material

Within 10' of ground-level directly connected impervious area

Deciduous trees 2-inch min. caliper

Evergreen trees 6 feet tall

Max 5% average slope for contributing area

Existing Trees: N 1/2 canopy

Directly connected impervious coverage equal to 1/2 canopy area

Trees from approved list

Within 20' of ground-level directly connected impervious area

Min. 4" caliper

Within drainage area

Maximum reduction of 25% of directly connected impervious area

5. Disconnection of Rooftop Runoff Encouraged in A and B soils N Imp. changed

to Perv. for

calc'sC and D soils evaluate permeability and water table depth

Maximum contributing flow length 75 feet

Downspouts 10 feet minimum from impervious surface

Maximum contributing area 500 sf, 2,000 sf w/level spreader

Drain through swale/filter strip equal to contributing flow length

Vegetative area average slope less than 5%

6. Stream Daylighting Stream channel capacity equal to or greater than culvert N Y

7. Rain Gardens Ponding depth should not exceed 6" 100% A & B N

Recommended Drainage area to infiltration area 5:1 max 40% C & D

Contribution area should be 1000 sf maximum

Typical Section 12"-18" Soil Media, 6-12" Washed Stone

Underdrain when required

Within 30' of downspout

Soil media 50%-70% sand, 30%-50% topsoil w/5% organic

2:1 flow path

8. Green Roofs 5 components: 100% N

Roof Structure

Waterproofing

Drainage System

Soil

Planting Types


Design Requirements Design Recommendations RR-Volume RR-AreaPractice

9. Stormwater Planters Recommended maximum contribution area 15,000 sf 30-100% N

Infiltration should be 10' min from structures

Should pond water for less than 12 hours and max 12" depth

For rooftop or courtyard runoff

Min. widths, 1.5' flow-through, 2.5' infiltration

Planter soil material 2 in/hr infiltration

Planter drainage layer 5 in/hr infiltration

Growing material 18" min. depth

Drainage material 12" min. depth

Native soil for infiltration planter min. 2 in/hr infiltration

3' min. infiltration depth to rock or groundwater

Infiltration planters should have no slope

C Soils Flow through 45% RRV credit

D Soils Flow through 30% RRV credit

10. Rain Barrels/Cisterns Min volume equal to WQV 100% N

Provide water budget analyis

11. Porous Pavement Bottom of reservoir 3 feet minimum above ground water A, B or C Soils 100% N

10-year 24 hour storm not to rise to pavement level 2' wide stone edge drain

Infiltration design IAW infiltration trenches of Ch 6. Slopes should not exceed 5%

Underlying soils should have minimum infiltration of 0.5 in/hr

25' down gradient from structures and septic systems

Legend

RR - Runoff Reduction

Y - Yes, can be used for runoff reduction credit

N - No, can not be used for runoff reduction credit

A, B, C, D - Hydrologic Soil Group Description (SCS)


III - 7

d. Tree Planting/Tree Pit – The plan provides for approximately 1,000 new trees.

e. Disconnection of Rooftop Runoff – The stormwater management plan is to direct

rooftop runoff from the new buildings to bioretention basins, infiltration areas, or

open channels wherever feasible. Approximately 167,000 square feet of new roofs

will be directed to these systems.

f. Stream Daylighting – There are currently two (2) wetlands that the discharge is

mostly piped to Choate Pond. The design will remove 600 feet of piping and

replace with an open channel to the extent feasible.

g. Rain Gardens – Bioretention areas, which will function similar to rain gardens, will

be located next to most of the new buildings.

h. Stormwater Planters – The bioretention areas will function similar to stormwater

planters. (See also Rain Gardens above)

i. Rain Barrels and Cisterns – Cisterns are proposed for the animal shelters.

j. Porous Pavement – Porous asphalt parking areas are proposed for new parking lots

that are not located in large cut or fill areas or subject to potential sediment load.

E. FLOOD ZONES

The site is located entirely out of the FEMA 100-year flood zone.

IV - 1

IV. STORMWATER QUALITY

A. STORMWATER QUALITY ANALYSIS

1. Existing Conditions

Refer to section II.C.1. and II.C.2 for a description of existing conditions.

2. Post-Development Conditions Without Treatment

The change in land use and increase in impervious area will result in the increase in

pollutant loading. Without treatment the pollutant loads would increase for Total

Suspended Solids (TSS), Total Phosphorus (TP), Total Nitrogen (TN), Metals, and

Bacteria.

3. Post-Development Conditions With Treatment

The use of wet extended detention ponds, porous pavement, bioretention filters, rain

gardens, and vegetated water quality swales are expected to reduce the pollutant

loading from the stormwater runoff. The treatment methods will be designed in

compliance with the NYDSDEC Stormwater Management Design Manual, dated

August 2010.

B. STORMWATER QUALITY MANAGEMENT MEASURES

The strategy of the Stormwater Management Plan is to tailor the treatment measures for

the various proposed land uses. A variety of measures will be used to maximize infiltration

of runoff into the ground when possible. Table No. 5 summarizes the standard

stormwater management practices and the feasibility of each for the project.

TABLE NO. 5

PACE UNIVERSITYPLEASANTVILLE, NEW YORK

DEC LIST OF APPROVED STORMWATER QUALITY MEASURES

STANDARD MANAGEMENT PRACTICES

Practice

I. Stormwater Ponds

Design Requirements Design RecommendationsDrainage Area size

Maintenance access to forebay P-2 to P-5 discouraged on Trout watersProtection at outlet, non-erosive velocities Stabilize inlet for 2-year stormMinimum Length to Width ratio 1.5:1 Partially submerged inlet pipeMinimum Surface Area to Drainage Area 1:100 Sediment depth in forebaySafety Bench 10’ min at 6% max slope, unless 4:1 or flatter side slopes Harden forebay bottom to ease sediment removalAquatic Bench up to 15’ and a maximum depth of 18” below normal water surface Provide WQV treatment off-linePond Buffer 25’ from maximum water surface Provide multiple treatment pathwaysWoody Vegetation 15’ min from toe of slope and 25’ min from spillway Long flow path, irregular shapeProvide low flow orifice Maintenance access to safety bench, riser and outlet w/vehicle turn aroundPond Drain, unless local slopes prohibit, capable of draining within 24 hours Maintenance access 12' wide, 15% max slopeAdjustable Gate Valve on WQ pipe and Pond Drain Protect low flow orifice w/trash rack or internal orifice protectionSide slopes to the pond shall not exceed 3:1 Size WQV-ED pipe and Pond Drain one pipe size larger than calculated

Pond fencing not encouraged

Soils Water Table Drainage Area Site Slope Head Additional Requirements RRV(acres) (ft)

P-1 Micropool Extended Detention HSG A may Require Liner OK 10 min. 15% or less 6' - 8' Permanent Pool 20% min. of WQV No

P-2 Wet Pond HSG A may Require Liner OK 25 min 15% or less 6' - 8' Permanent Pool 100% min. of WQV No

P-3 Wet Extended Detention Pond HSG A may Require Liner OK 25 min 15% or less 6' - 8' Permanent Pool 50% min. of WQV No

P-4 Multiple Pond HSG A may Require Liner OK 25 min 15% or less 6' - 8' Permanent Pool 50% min. of WQV No

P-5 Pocket Pond OK Below WT 5 max 15% or less 4' Permanent Pool 50% min. of WQV No

Forebay: 10% min. of WQV, at each inflow w/10% of flow, 4'-6' deep

728 DEC Approved Stormwater Measures.xlsx - Standard Practices Divney Tung Scwhalbe, LLP

Practice

II. Wetlands

Design Requirements Design RecommendationsMaximize flow paths Discouraged on Trout watersMinimal flow path of 2:1 (length to width) Use microtopology to enhance wetland diversitySurface area at least 1% of contributing area Maximize internal flow lengthAt least 35% of surface area to have depth of 6" or lessAt least 65% of surface area to have depth of 18" or lessAt least 25% of the WQV shall be in deepwater zones with depth of greater than 4'Max water surface 3' above permanent pool.Wetland plant buffer 25’ from maximum water surface15' setback to structures from wetland bufferForebay 4' to 6' deep and stores 10% of WQV


W-1 Shallow Wetland HSG A may Require Liner OK 25 min 8% or less 3' - 5' No

W-2 Extended Detention Wetland HSG A may Require Liner OK 25 min 8% or less 3' - 5' 50% of WQV in Permanent Pool No

W-3 Pond/Wetland HSG A may Require Liner OK 25 min 8% or less 3' - 5' No

W-4 Pocket Wetland OK Below WT 5 max 8% or less 2' - 3' No


Practice

III. Infiltration

Design Requirements Design RecommendationsOne test hole per 5000 sf Non-erosive velocities for 10-year overflow2 borings per facility Line trench and dry wells side with filter fabricClay content less than 20% and silt/clay content less than 40% Stone bottom should be flatCan not be located in fills, except top quarter of trench/dry wellBottom 3' min. above seasonally high ground water100' min from water supply wellDe-water entire WQV within 48 hoursDesign as off-line practice25% of the WQV in pretreatment50% of the WQV in pretreatment, if fc greater than 2 in/hr100% of the WQV in pretreatment, if fc greater than 5 in/hrExfiltrate WQV through bottom, sides not consideredDo not use practice area as sediment trapObservation well required for trench and dry wellProvide direct access


I-1 Infiltration Trench Infiltration > 0.5 in/hr 3' Separation 5 max 15% or less 1' 25' min from structures 90%sand or fine gravel coarse above gravel

I-2 Shallow Infiltration Basin Infiltration > 0.5 in/hr 3' Separation 10 max 15% or less 3' 25' min from structures 90%

I-3 Dry Well Infiltration > 0.5 in/hr 3' Separation 1 max 15% or less 1' 10' min. from structures 90%


Practice

IV. Filters

Design Requirements Design RecommendationsOff-line if from storm pipe Drainage Area sizeOverflow for percentage of WQV and 10-year storm4" min. perforated pipe underdrain25% WQV pre-treatmentTemporarily hold 75% of WQVSedimentation pretreatment if impervious cover less than 75%12" min. filter bed depth, 18" typical


F-1 Surface Sand Filter OK 2' 10 max 6% or less 5' 18" min. Sand No

F-2 Underground Sand Filter OK 2' 2 max 6% or less 5' - 7' 18" min. Sand No

F-3 Perimeter Sand Filter OK 2' 2 max 6% or less 2' - 3' 12" min. Sand No

F-4 Organic Filter OK 2' 5 max 6% or less 2' - 4' Peat/sand mix or leaf compost No

F-5 Bioretention OK 2' 5 max 6% or less 5' 2.5' - 4' planting soil, mulch layer, 6" surface

ponding

80% A & B

40% C &DRecommended pretreatment: filter strip, gravel

diaphragm, mulch layer

V. Open Channels

Design Requirements Design RecommendationsMax. slope 4% Check dams as required to retain WQVPeak 2-year velocity 5.0 fps Pea gravel diaphragm and gentle side slopes for lateral sheet flow to channelConvey 10-year storm w/6" of freeboard Max ponding depth 12" at midpoint, 18" at end point.48 hour maximum ponding time2:1 max side slope, 3:1 typical10% min WQV in pre-treatmentStore WQV, to be released over 30 minutesBottom width 2' min., 8' max


O-1 Dry Swale Made Soil 2' 5 max 4% or less 3' - 5' 30" Permeable Soil, 6" gravel, 4" Perf. PVC 20% A & B

10% C &DO-2 Wet Swale OK Below WT 5 max 4% or less 1' Not for use in residential areas No


IV - 6

Under the proposed master Plan Update a portion of the redevelopment areas will use the

alternative practices defined in Chapter 9, Redevelopment Projects, of the NYS

Stormwater Management Design Manual. The Stormwater Management Plan is based on

the analysis of the existing and proposed stormwater conditions discussed in the previous

section of this report and the design criteria of the stormwater management practices

noted below. As the Proposed Action will involve the construction of an approximately

3.5-acre increase in on-site impervious surfaces associated with pavements and roofs,

higher pollutant loadings would be expected to occur on the developed site. The total

water quality volume provided is shown on Table No. 6. An outline of the varying

stormwater quality management BMP’s, both structural and non-structural, to be

implemented both during construction and/or after project completion is presented below.

1. Wet Extended Detention Pond

Wet extended detention ponds will provide treatment of the NYSDEC required water

quality volume through extended detention. Each pond incorporates a pool of water at

its outlet to reduce sediment re-suspension. The treatment system includes a stone-

lined sediment forebay, stone rip-rap berm, permanent pool, outlet control drain

structure, and emergency overflow weir. The wet extended detention pond will treat

the 90% rainfall event through filtration and detain all storm events up to and

including a 100-year storm. In addition, each pond’s outlet control structure is

designed such that downstream flows will be less than or equal to existing conditions.

The modifications to Choate Pond are intended to allow the pond to function as a wet

extended detention pond.

TABLE NO. 6

PACE UNIVERSITY


WATER QUALITY AND RUNOFF REDUCTION VOLUME CALCULATIONS

Sub-Basin Bldg Name Bldg Area Adjacent

Imp.

Total Area Required

WQV

Soil S Min.Req'd

Volume

Technique Area Provided

WQV

Downstream

Practice

Notes

(sf) (sf) (sf) (cf) (cf) (sf) (cf)

AA2 ENV CTR 930 1,000 1,930 199 B 0.40 79 Rain Garden 350 228 Pond AA2

AA2 ENV CTR 1,630 1,000 2,630 271 B 0.40 108 Rain Garden 500 325 Pond AA2

AA2 ENV CTR 1,630 1,000 2,630 271 B 0.40 108 Rain Garden 500 325 Pond AA2

DD Field House 9,989 9,989 1,028 C 0.30 308 Bioretention 1,000 1,300 n/a

BB1 Future Theater 13,993 1,700 15,693 1,615 B 0.40 646 Bioretention 1,300 1,690 Choate Pond Future Bldg

BB1 Kessel Student 16,957 16,957 1,745 B 0.40 698 Bioretention 3,400 4,420 Choate Pond

BB3 New Marks 9,731 13,000 22,731 2,339 B 0.40 936 Bioretention 2,000 2,600 Choate Pond

BB1 RH A - E 10,173 16,000 26,173 2,694 B 0.40 1,077 Infiltration 5,500 2,750 Choate Pond

BB1 RH A - W 18,916 18,916 1,947 B 0.40 779 Infiltration 1,282 641 Choate Pond

BB1 RH B - N 11,042 11,042 1,136 B 0.40 455 Infiltration 2,400 1,200 Choate Pond

BB1 RH B - S 9,100 9,100 937 B 0.40 375 Infiltration 2,000 1,000 Choate Pond

BB1 RH C - E 9,604 2,500 12,104 1,246 B 0.40 498 Bioretention 3,600 4,680 Choate Pond

BB1 RH C - W 13,216 2,500 15,716 1,617 B 0.40 647 Bioretention 2,800 3,640 Choate Pond

BB1 RH D 12,276 7,500 19,776 2,035 B 0.40 814 Bioretention 1,600 2,080 Pond AA2

BB1 RH E 10,400 2,300 12,700 1,307 B 0.40 523 Bioretention 2,800 3,640 Pond AA2

BB1 RH F 10,400 2,000 12,400 1,276 B 0.40 510 Bioretention 1,600 2,080 Pond AA2

BB3 Welcome Center 7,533 54,000 61,533 6,333 B 0.40 2,533 Bioretention 5,000 6,500 Choate Pond

AA2 Animal Shelters 1,970 1,970 203 C 0.30 61 Cistern n/a 200 Pond AA2 1500 gal cistern

Other Areas

GG Parking - Softball-S 16,000 16,000 1,647 B 0.40 659 Porous Pavement 4,860 1,944 n/a

GG Parking - Softball-S 12,000 12,000 1,235 B 0.40 494 Porous Pavement 3,780 1,512 n/a

Entry Road 28,000 28,000 2,882 B 0.40 1,153 Bioretention 2,300 2,990 Choate Pond

BB1 Parking - Theatre 5,800 5,800 597 B 0.40 239 Porous Pavement 1,764 706 Choate Pond

DD Parking - Choate 12,000 12,000 1,235 B 0.40 494 Porous Pavement 3,740 1,496 n/a

BB1 Parking - RHB - S 6,700 6,700 690 B 0.40 276 Porous Pavement 2,000 800 Choate Pond

BB1 Parking - RHA - W 14,400 14,400 1,482 B 0.40 593 Porous Pavement 4,387 1,755 Choate Pond

BB2 Parking - North Hall 10,700 10,700 1,101 B 0.40 440 Bioretention 900 1,170 Choate Pond

AA2 Parking RH E 11,500 11,500 1,184 B 0.40 473 Porous Pavement 3,600 1,440 Pond AA2

AA2 Parking RH F 15,000 15,000 1,544 B 0.40 618 Porous Pavement 4,680 1,872 Pond AA2

Total (sf - cf) 169,490 236,600 406,090 41,793 16,594 54,983

Total (ac / ac-ft) 3.89 5.43 9.32 0.96 0.38 1.26

Green Infrastructure

IV - 8

2. Rain Garden/Bioretention Filter

Rain Gardens and Bioretention Filters are stormwater management practices that

manage and treat stormwater runoff using a conditioned planting soil bed and planting

materials to filter runoff stored within a shallow depression. The method combines

physical filtering and adsorption with bio-geochemical processes to remove pollutants.

3. Porous Pavement

Porous pavements infiltrate rainfall through the surface, thereby reducing stormwater

runoff from a site and providing some pollutant uptake in underlying soils.

4. Open Channels

A vegetated channel designed to filter stormwater runoff and meet velocity targets for

the water quality design storm and the two year storm events. A grass channel is

parabolic shaped with a minimum 2-foot wide center section and side walls at 2:1 slope

or flatter.

5. Catch Basin Sumps

All new catch basins will be provided with sumps to capture and collect sediment and

debris prior to it entering the stormwater conveyance system. Each catch basin sump

will be cleaned out periodically to remove the dirt and debris as part of routine campus

maintenance.

IV - 9

6. Stormwater Pollution Prevention Plan

In compliance with requirements established for the NYSDEC SPDES General Permit

For Stormwater Discharges from Construction Activity (Permit No. GP-0-10-001) a

Stormwater Pollution Prevention Plan will be prepared and implemented. As a result,

an Erosion Control Plan shall be prepared as part of the contract documents and will

require that the erosion and sedimentation controls set forth thereon be implemented

before the start of construction and further such controls will be monitored and

maintained during construction. Stabilization of the site shall also comply with the

conditions or requirements set forth therein and as shall further be established by the

Town of Mount Pleasant.

Several temporary structural practices to be utilized to mitigate any potential impacts

include, but shall not be limited to, surrounding material stockpiles with silt fencing

and hay bale dams, excavated and embankment areas will be graded to permit drainage

and the runoff will be intercepted in ditches with silt barriers or collected in settling

basins to permit sedimentation, and stabilized construction entrances will be

constructed and maintained during construction to minimize the off-site migration of

sediment.

V - 1

V. TECHNICAL APPENDIX

A. METHODOLOGY

1. Zero Increase in Watershed Peak Runoff

As typical for standard development practices, the peak rate of stormwater discharge

from the site after the completion of development will not exceed the estimated pre-

development peak discharge.

2. Storm Frequencies

The storm frequencies to be used as a basis for computing peak rate of discharge shall

be storms expected once every 1, 2, 10, 25, and 100 years with durations of 24 hours

as defined by the U.S. Department of Agriculture Soil Conservation Service.

3. Technical Approach

The method used for estimating peak discharge shall be as per the document released

by the Engineering Division of the U.S. Department of Agriculture Soil Conservation

Service titled “Urban Hydrology for Small Watersheds”, Technical Release No. 55,

dated June 1986, Type III Storm Distribution. This criterion governs the data that is

input into the software, namely the Haestead Methods Quick TR-55 computer

program. A summary of the flows under existing and proposed conditions is provided.

The complete input and output data is available upon request.

V - 2

4. Soil Classifications

The soil classifications and their limits were provided from mapping compiled by the

U.S. Department of Agriculture Soil Conservation Service.1

5. Detention Requirements

The continuity equation and level pool reservoir routing methods are used to route

watershed inflow hydrographs through detention basins.

6. Rainfall Intensity

Frequency and intensities, which have been used in this report, are as follows:

WESTCHESTER COUNTY

RAINFALL INTENSITY BY STORM FREQUENCY2

Storm Frequency

Year

Rainfall Intensity (24-Hour Period)

(Inches)

100 8.5 25 6.3 10 5.0 2 3.5 1 3.0

1 USDA, Soil Survey of Westcheter County, New York, 2002. 2 Northeast Regional Climate Data Center

V - 3

B. CALCULATIONS

1. Curve Numbers

Curve numbers have been calculated for the sub-watersheds using curve numbers for

various land uses provided in Tables 2.2a – 2.2d in TR-55, Urban Hydrology for

Small Watersheds, June 1986. The curve number calculations for pre- and post

development are shown on Table No. 7 and 8.

2. Times of Concentration

The times of concentration (Tc) have been estimated to determine the time of the

longest hydraulic route within the sub-watershed being analyzed. These routes

include overland, shallow-concentrated and channel or pipe flows. The time of

concentration for pre- and post development are shown on Table No. 9 and 10.

3. Pipe Sizing

The pipe capacity design is determined by using the Rational Method, which is well

suited for small areas and will include standard practices that take into consideration

headwater, velocity, slope, area and diameter. Manning’s Equation is used for pipes

that have sufficient length and constant slopes to establish uniform flow at normal

depth without backwater or pressure head. The storm pipes conveying water to the

stormwater basins will be sized for the 10-year storm with a minimum diameter of 15

inches. The outlet pipes from the stormwater basins will be sized for the 100-year

storm.

V - 4

4. Channel Protection Volume

Stream Channel Protection Volume (CPv) requirements are designed to protect

stream channels from erosion. Typically, in New York State, this goal is accomplished

by providing 24-hour extended detention of the one-year, 24-hour storm event. The

detention time is calculated by the storm modeling software PondPack. To reduce the

risk of clogging an anti-clogging device will be used for the bottom orifice of the

outlet control structure.

5. Water Quality Volume

The required water quality volume has been calculated in accordance with the New

York State Stormwater Management Design Manual, August 2010.

TABLE NO. 7

PACE UNIVERSITY


EXISTING CONDITIONS CURVE NUMBER COMPUTATIONS

Watershed Total Area Imp Wooded Open B C B/C Rev B Rev C Wood B Wood C Open B Open C Imp B Imp C CN S

(ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac)

A 50.48 8.77 25.98 15.73 37.41 9.33 3.74 40.40 10.08 20.79 5.19 12.59 3.14 7.02 1.75 66.7 0.38

B 54.39 13.88 19.82 20.69 41.60 0.79 11.45 52.84 1.55 19.25 0.57 20.10 0.59 13.48 0.40 68.6 0.40

C 15.52 1.30 12.08 2.14 8.80 4.64 2.08 10.16 5.36 7.91 4.17 1.40 0.74 0.85 0.45 64.1 0.37

D 7.98 2.00 1.28 4.70 6.86 1.12 0.00 6.86 1.12 1.10 0.18 4.04 0.66 1.72 0.28 70.7 0.39

E 3.33 2.55 0.11 0.67 0.56 2.77 0.00 0.56 2.77 0.02 0.09 0.11 0.56 0.43 2.12 91.7 0.32

F 4.42 2.33 0.72 1.37 2.55 1.87 0.00 2.55 1.87 0.42 0.30 0.79 0.58 1.34 0.99 82.3 0.36

G 4.95 2.90 0.34 1.71 4.80 0.15 0.00 4.80 0.15 0.33 0.01 1.66 0.05 2.81 0.09 82.4 0.40

H 2.81 0.46 0.00 2.35 2.81 0.00 0.00 2.81 0.00 0.00 0.00 2.35 0.00 0.46 0.00 67.1 0.40

1. Hydrologic Soil Group classification, see Soil Survey of Putnam and Westchester Counties, New York. United States Department of Agriculture, Soil Conservation Service.

2. S=Hydrologic Soil Group (HSG) Specific Reduction Factor

2. Cover Type as listed per Tables 2-2a.-c.-Runoff Curve Numbers for Urban Areas, TR-55 Urban Hydrology for Small Watersheds, Second Edition, June 1986, page 2-5.

3. Hydrologic Condition either Poor, Fair or Good per Tables 2-2a.-c.-Runoff Curve Numbers for Urban Areas, TR-55 Urban Hydrology for Small Watersheds, Second Edition, June 1986, page 2-5.

4. Specific Reduction factors for the HSGs per NYSSMDM, Chapter 4, Section 4.3:HSG A 0.55

HSG B 0.40

HSG C 0.30

HSG D 0.20

5. CN values from Tables 2-2a.-c.-Runoff Curve Numbers for Urban Areas, TR-55 Urban Hydrology for Small Watersheds, Second Edition, June 1986, page 2-5.

728 Stormwater Analysis GP-0-10-001 Updated.xls12/21/2011 Divney Tung Schwalbe, LLP

TABLE NO. 8

PACE UNIVERSITY


DEVELOPED CONDITIONS CURVE NUMBER COMPUTATIONS

Watershed Total Area Imp Wooded Open B C B/C Rev B Rev C Wood B Wood C Open B Open C Imp B Imp C CN S

(ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac) (ac)

AA-1 15.39 0.32 10.56 4.51 10.78 4.61 0.00 10.78 4.61 7.40 3.16 3.16 1.35 0.22 0.10 61.9 0.37

AA-2 33.39 8.16 14.83 10.40 24.94 4.71 3.74 28.09 5.30 12.47 2.36 8.75 1.65 6.86 1.30 69.1 0.38

BB1 28.80 10.73 5.20 12.87 26.41 0.46 0.59 26.99 1.81 4.87 0.33 12.06 0.81 10.06 0.67 74.2 0.39

BB2 22.84 5.20 11.23 6.41 11.68 0.30 10.86 22.27 0.57 10.95 0.28 6.25 0.16 5.07 0.13 66.7 0.40

BB3 5.32 2.71 0.50 2.11 5.32 0.00 0.00 5.32 0.00 0.50 0.00 2.11 0.00 2.71 0.00 79.3 0.40

CC 15.52 1.43 12.04 2.05 8.80 4.64 2.08 10.16 5.36 7.88 4.16 1.34 0.71 0.94 0.49 64.4 0.37

DD 7.96 2.52 1.01 4.43 6.83 1.13 0.00 6.83 1.13 0.87 0.14 3.80 0.63 2.16 0.36 73.2 0.39

EE 2.99 2.03 0.00 0.96 0.23 2.76 0.00 0.23 2.76 0.00 0.00 0.07 0.89 0.16 1.87 90.0 0.31

FF 4.22 2.11 0.67 1.44 2.36 1.86 0.00 2.36 1.86 0.37 0.30 0.81 0.63 1.18 0.93 81.6 0.36

GG 4.64 2.21 0.30 2.13 4.49 0.15 0.00 4.49 0.15 0.29 0.01 2.06 0.07 2.14 0.07 78.5 0.40

HH 2.81 0.28 0.00 2.53 2.81 0.00 0.00 2.81 0.00 0.00 0.00 2.53 0.00 0.28 0.00 64.7 0.40

1. Hydrologic Soil Group classification, see Soil Survey of Putnam and Westchester Counties, New York. United States Department of Agriculture, Soil Conservation Service.

2. S=Hydrologic Soil Group (HSG) Specific Reduction Factor

2. Cover Type as listed per Tables 2-2a.-c.-Runoff Curve Numbers for Urban Areas, TR-55 Urban Hydrology for Small Watersheds, Second Edition, June 1986, page 2-5.

3. Hydrologic Condition either Poor, Fair or Good per Tables 2-2a.-c.-Runoff Curve Numbers for Urban Areas, TR-55 Urban Hydrology for Small Watersheds, Second Edition, June 1986, page 2-5.

4. Specific Reduction factors for the HSGs per NYSSMDM, Chapter 4, Section 4.3:HSG A 0.55

HSG B 0.40

HSG C 0.30

HSG D 0.20

5. CN values from Tables 2-2a.-c.-Runoff Curve Numbers for Urban Areas, TR-55 Urban Hydrology for Small Watersheds, Second Edition, June 1986, page 2-5.

728 Stormwater Analysis GP-0-10-001 Updated.xls12/21/2011 Divney Tung Schwalbe, LLP

TABLE NO. 9

PACE UNIVERSITY


EXISTING TIME OF CONCENTRATION (OR TRAVEL TIME)

SHEET FLOW

A B C D E F G

1. Surface Description (See Table Below) 1 9 9 9 6 6 6 9

2. Mannings Roughness Coefficient n 0.4 0.4 0.4 0.24 0.24 0.24 0.4

3. Flow Length (Total L<100FT) L ft 100 100 100 100 80 40 85

4. 2-YR 24-HR Rainfall 2 P2 in 3.5 3.5 3.5 3.5 3.5 3.5 3.5

5. Land Slope s ft/ft 0.15 0.09 0.10 0.07 0.05 0.08 0.14

6. Travel Time

Tt = (0.007(nL)0.8)/(P20.5*s0.4) Tt hr 0.15 0.19 0.18 0.14 0.13 0.06 0.14

SHALLOW CONCENTRATED FLOW

7. Surface Description (paved or unpaved) unpaved unpaved unpaved unpaved Paved

8. Flow Length L ft 2000 1100 800 100 0 0 130

9. Watercourse Slope s ft/ft 0.13 0.22 0.55 0.35 0.00 0.00 0.07

10. Average Velocity 3 V ft/s 5.50 7.50 12.00 9.00 0.00 0.00 5.20

11. Tt = L / 3600V Tt hr 0.10 0.04 0.02 0.00 0.00 0.00 0.01

CHANNEL FLOW

12. Cross Sectional Flow Area a ft2 1.25 1.25 1.25 1.25 1.25 1.25 1.25

13. Wetted Perimeter pw ft 2.71 2.71 2.71 2.71 2.71 2.71 2.71

14. Hydraulic Radius, r = a/pw r ft 0.46 0.46 0.46 0.46 0.46 0.46 0.46

15. Channel Slope s ft/ft 0.05 0.04 0.02 0.03 0.03 0.05 0.01

16. Manning's Roughness Coefficient 4 n 0.015 0.015 0.015 0.015 0.015 0.015 0.015

17. Velocity = (1.49r2/3s1/2)/n V ft/s 13.46 11.28 8.00 10.48 10.52 12.79 5.93

18. Flow Length L ft 1400 1300 880 800 540 580 390

19. Tt = L / 3600V Tt hr 0.03 0.03 0.03 0.02 0.01 0.01 0.02

TOTAL WATERSHED Tc Tc hr 0.28 0.26 0.23 0.16 0.15 0.08 0.16

1 Smooth (conc, asphalt, gravel, bare soil) 0.011

2 Fallow (no residue) 0.05

3 Cultivated Soils, Residue Cover < 20% 0.06

4 Cultivated Soils, Residue Cover > 20% 0.17

5 Short Grass Prairie 0.15

6 Dense Grass 0.24

7 Bermuda Grass 0.41

8 Range (natural) 0.13

9 Woods (light) 0.4

1 Table 3-1. - Roughness coefficients (Manning's n) for SHEET FLOW, TR-55 Urban Hydrology for

Small Watersheds, page 3-3.

2 Westchester County Rainfall, NYSDEC Amendment NY-1, November 7, 1990, page 2-14.5

3 Figure 3-1. - Average velocities for estimating travel time for shallow concentrated flow, TR-55

Urban Hydrology forSmall Watersheds, page 3-2.

4 Roughness coefficients (Manning's n) for CHANNEL FLOW. See Handbook of Hydraulics or equal.

ROUGHNESS COEFFICIENTS (Manning's n)

FOR SHEET FLOW 1

WATERSHED/ SUBBASIN ID


TABLE NO. 10

PACE UNIVERSITY


DEVELOPED TIME OF CONCENTRATION (OR TRAVEL TIME)

SHEET FLOW

AA-1 AA-2 BB1 BB2 BB3 CC DD EE FF GG

1. Surface Description (See Table Below) 1 9 9 9 1 1 9 6 6 6 9

2. Mannings Roughness Coefficient n 0.4 0.4 0.4 0.011 0.011 0.4 0.24 0.24 0.24 0.4

3. Flow Length (Total L<100FT) L ft 100 100 100 0 0 100 100 80 40 85

4. 2-YR 24-HR Rainfall 2 P2 in 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5

5. Land Slope s ft/ft 0.15 0.15 0.09 0.00 0.00 0.10 0.07 0.05 0.08 0.14

6. Travel Time

Tt = (0.007(nL)0.8)/(P20.5*s0.4) Tt hr 0.15 0.15 0.19 0.00 0.00 0.18 0.14 0.13 0.06 0.14

SHALLOW CONCENTRATED FLOW

7. Surface Description (paved or unpaved) unpaved unpaved unpaved unpaved unpaved Paved

8. Flow Length L ft 2000 2000 1100 0 0 800 100 0 0 130

9. Watercourse Slope s ft/ft 0.13 0.13 0.22 0.00 0.00 0.55 0.35 0.00 0.00 0.07

10. Average Velocity 3 V ft/s 5.50 5.50 7.50 0.00 0.00 12.00 9.00 0.00 0.00 5.20

11. Tt = L / 3600V Tt hr 0.10 0.10 0.04 0.00 0.00 0.02 0.00 0.00 0.00 0.01

CHANNEL FLOW

12. Cross Sectional Flow Area a ft2 1.25 1.25 1.25 0 0 1.25 1.25 1.25 1.25 1.25

13. Wetted Perimeter pw ft 2.71 2.71 2.71 0 0 2.71 2.71 2.71 2.71 2.71

14. Hydraulic Radius, r = a/pw r ft 0.46 0.46 0.46 0 0 0.46 0.46 0.46 0.46 0.46

15. Channel Slope s ft/ft 0.05 0.05 0.04 0.00 0.00 0.02 0.03 0.03 0.05 0.01

16. Manning's Roughness Coefficient 4 n 0.015 0.015 0.015 0 0 0.015 0.015 0.015 0.015 0.015

17. Velocity = (1.49r2/3s1/2)/n V ft/s 13.46 13.46 11.28 0.00 0.00 8.00 10.48 10.52 12.79 5.93

18. Flow Length L ft 1400 1400 1300 0 0 880 800 540 580 390

19. Tt = L / 3600V Tt hr 0.03 0.03 0.03 0.00 0.00 0.03 0.02 0.01 0.01 0.02

TOTAL WATERSHED Tc Tc hr 0.28 0.28 0.26 0.00 0.00 0.23 0.16 0.15 0.08 0.16

1 Smooth (conc, asphalt, gravel, bare soil) 0.011

2 Fallow (no residue) 0.05

3 Cultivated Soils, Residue Cover < 20% 0.06

4 Cultivated Soils, Residue Cover > 20% 0.17

5 Short Grass Prairie 0.15

6 Dense Grass 0.24

7 Bermuda Grass 0.41

8 Range (natural) 0.13

9 Woods (light & dense) 0.4

1 Table 3-1. - Roughness coefficients (Manning's n) for SHEET FLOW, TR-55 Urban Hydrology for

Small Watersheds, page 3-3.

2 Westchester County Rainfall, NYSDEC Amendment NY-1, November 7, 1990, page 2-14.5

3 Figure 3-1. - Average velocities for estimating travel time for shallow concentrated flow, TR-55

Urban Hydrology forSmall Watersheds, page 3-2.

4 Roughness coefficients (Manning's n) for CHANNEL FLOW. See Handbook of Hydraulics or equal.

ROUGHNESS COEFFICIENTS (Manning's n)

FOR SHEET FLOW 1

WATERSHED/ SUBBASIN ID


V - C

C. POND PACK MODELING

The Pond Pack Modeling results are available in PDF format upon request.

V-C-1

POND PACK SUMMARY

EXISTING CONDITIONS

Outlet B

Outlet CA

ddlink 120

Addlin

k 110

Addlink 100

Addlink 90

Addlink 80

Addlink 70 Addlink 60 Addlink 50 Addlink 40 Addlink 30

Addlink 20

Addlink 10

AD

EF

G

CB

Junc A

Junc GJunc FJunc E

Junc D

Pond C

Pond B

DP 1

File.... J:\728 Pace - Pleasantville - Master Plan\728 Engineering\Stormwater\PondPak\728 Existing Conditions.ppw

Name.... Watershed

Type.... Master Network Summary Page 1.01

MASTER DESIGN STORM SUMMARY

Network Storm Collection: Sleepy Hollow

Total

Depth Rainfall

Return Event in Type RNF ID

------------ ------ ---------------- ----------------

1 3.0000 Synthetic Curve TypeIII 24hr





MASTER NETWORK SUMMARY

SCS Unit Hydrograph Method

(*Node=Outfall; +Node=Diversion;)

(Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt)

Max

Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage

Node ID Type Event ac-ft Trun hrs cfs ft ac-ft

----------------- ---- ------ ---------- -- --------- -------- -------- ------------

A AREA 1 2.460 12.2440 19.57

A AREA 2 3.575 12.2440 31.01

A AREA 10 7.583 12.2070 72.24

A AREA 25 11.602 12.2070 113.38

A AREA 100 19.092 12.2070 188.67

B AREA 1 3.035 12.2360 26.22

B AREA 2 4.323 12.2020 39.79

B AREA 10 8.870 12.2010 87.85

B AREA 25 13.362 12.2010 134.53

B AREA 100 21.650 12.2010 218.83

C AREA 1 .606 12.2340 4.57

C AREA 2 .912 12.2040 7.87

C AREA 10 2.044 12.1740 20.20

C AREA 25 3.206 12.1740 32.93

C AREA 100 5.410 12.1730 56.67

S/N:

Bentley PondPack (10.01.04.00) 6:40 PM 12/21/2011

Bentley Systems, Inc.


Name.... Watershed






Max



----------------- ---- ------ ---------- -- --------- -------- -------- ------------

D AREA 1 .506 12.1560 5.28

D AREA 2 .707 12.1380 7.71

D AREA 10 1.407 12.1370 16.06

D AREA 25 2.089 12.1370 24.04

D AREA 100 3.335 12.1370 38.25

*DP 1 JCT 1 7.357 R 12.2070 45.58

*DP 1 JCT 2 10.432 R 12.2070 68.52

*DP 1 JCT 10 21.340 R 12.2060 148.97

*DP 1 JCT 25 32.176 R 12.1800 226.16

*DP 1 JCT 100 52.261 R 12.2440 460.16

E AREA 1 .600 12.1190 6.80

E AREA 2 .732 12.1190 8.22

E AREA 10 1.134 12.1190 12.44

E AREA 25 1.488 12.1190 16.06

E AREA 100 2.091 12.1190 22.13

F AREA 1 .508 12.1090 6.39

F AREA 2 .656 12.1090 8.24

F AREA 10 1.134 12.1080 14.00

F AREA 25 1.570 12.0990 19.11

F AREA 100 2.333 12.0990 27.78

G AREA 1 .569 12.1370 6.53

G AREA 2 .735 12.1370 8.46

G AREA 10 1.270 12.1370 14.52

G AREA 25 1.758 12.1370 19.89

G AREA 100 2.613 12.1370 29.01

JUNC A JCT 1 7.357 R 12.2070 45.58

JUNC A JCT 2 10.432 R 12.2070 68.52

JUNC A JCT 10 21.340 R 12.2060 148.97

JUNC A JCT 25 32.176 R 12.1800 226.16

JUNC A JCT 100 52.261 R 12.2440 460.16

S/N:




Name.... Watershed






Max



----------------- ---- ------ ---------- -- --------- -------- -------- ------------

JUNC D JCT 1 5.178 R 12.1370 28.79

JUNC D JCT 2 7.230 R 12.1380 40.31

JUNC D JCT 10 14.422 R 12.1380 80.24

JUNC D JCT 25 21.502 R 12.4260 127.03

JUNC D JCT 100 34.546 R 12.2680 278.30

JUNC E JCT 1 1.560 R 12.1180 19.57

JUNC E JCT 2 1.982 R 12.1160 24.74

JUNC E JCT 10 3.324 R 12.1160 40.71

JUNC E JCT 25 4.539 R 12.1160 54.74

JUNC E JCT 100 6.653 R 12.1100 78.51

JUNC F JCT 1 .995 R 12.1160 12.77

JUNC F JCT 2 1.292 R 12.1160 16.53

JUNC F JCT 10 2.250 R 12.1100 28.30

JUNC F JCT 25 3.127 R 12.1100 38.75

JUNC F JCT 100 4.666 R 12.1100 56.48

JUNC G JCT 1 .526 R 12.1370 6.53

JUNC G JCT 2 .682 R 12.1370 8.46

JUNC G JCT 10 1.188 R 12.1370 14.52

JUNC G JCT 25 1.651 R 12.1370 19.89

JUNC G JCT 100 2.464 R 12.1370 29.01

POND B IN POND 1 3.238 R 12.2360 30.63

POND B IN POND 2 4.704 R 12.2340 46.89

POND B IN POND 10 9.979 R 12.2010 103.26

POND B IN POND 25 15.271 R 12.2010 153.22

POND B IN POND 100 25.143 R 12.2010 240.93

POND B OUT POND 1 3.238 12.6050 14.77 280.84 .744

POND B OUT POND 2 4.704 12.5800 22.89 281.14 1.154

POND B OUT POND 10 9.978 12.5630 51.52 282.19 2.653

POND B OUT POND 25 15.271 12.4590 97.97 282.93 3.792

POND B OUT POND 100 25.142 12.2940 210.49 283.31 4.465

S/N:




Name.... Watershed






Max



----------------- ---- ------ ---------- -- --------- -------- -------- ------------

POND C IN POND 1 .531 R 12.2340 4.57

POND C IN POND 2 .810 R 12.2040 7.87

POND C IN POND 10 1.856 R 12.1740 20.20

POND C IN POND 25 2.939 R 12.1740 32.93

POND C IN POND 100 5.007 R 12.1730 56.67

POND C OUT POND 1 .531 12.2700 4.48 311.02 .008

POND C OUT POND 2 .810 12.2690 7.44 311.34 .020

POND C OUT POND 10 1.856 12.3150 16.25 312.16 .117

POND C OUT POND 25 2.939 12.4130 20.15 312.78 .352

POND C OUT POND 100 5.007 12.5090 24.36 313.60 1.005

S/N:



V-C-2

POND PACK SUMMARY

DEVELOPED CONDITIONS

Route 60

Route 50

Outlet B

Addlink 160

Addlink 140

Addlink 13

0

Addlink 150

Addlink 120

Addlink 110

Addlink 100

Addlink 90

Addlink 80

Addlink 70 Addlink 60 Addlink 50 Addlink 40 Addlink 30

Addlink 20

Addlink 10

AA-1

DDEE FF

GG

CBB1

BB2

BB3

AA-2

Junc A

Junc GJunc FJunc EJunc D

Junc 10 Pond C

Pond B

Pond AA-2

DP 1

File.... J:\728 Pace - Pleasantville - Master Plan\728 Engineering\Stormwater\PondPak\728 Proposed Conditions.ppw

Name.... Watershed


MASTER DESIGN STORM SUMMARY

Network Storm Collection: Sleepy Hollow

Total

Depth Rainfall

Return Event in Type RNF ID

------------ ------ ---------------- ----------------










Max



----------------- ---- ------ ---------- -- --------- -------- -------- ------------

AA-1 AREA 1 .511 12.3160 3.26

AA-1 AREA 2 .789 12.2800 5.97

AA-1 AREA 10 1.844 12.2430 16.73

AA-1 AREA 25 2.947 12.2070 28.13

AA-1 AREA 100 5.062 12.2070 49.71

AA-2 AREA 1 1.863 12.2440 15.70

AA-2 AREA 2 2.654 12.2440 23.77

AA-2 AREA 10 5.445 12.2070 52.53

AA-2 AREA 25 8.203 12.2070 80.61

AA-2 AREA 100 13.291 12.2070 131.37

BB1 AREA 1 2.179 12.2020 20.62

BB1 AREA 2 2.975 12.2010 29.04

BB1 AREA 10 5.673 12.2010 57.15

BB1 AREA 25 8.251 12.2010 83.43

BB1 AREA 100 12.897 12.2010 129.61

S/N:




Name.... Watershed






Max



----------------- ---- ------ ---------- -- --------- -------- -------- ------------

BB2 AREA 1 1.113 12.2360 9.10

BB2 AREA 2 1.618 12.2340 14.36

BB2 AREA 10 3.431 12.2010 33.59

BB2 AREA 25 5.249 12.2010 52.60

BB2 AREA 100 8.638 12.2010 87.34

BB3 AREA 1 .527 12.1590 5.65

BB3 AREA 2 .694 12.1580 7.52

BB3 AREA 10 1.242 12.1580 13.55

BB3 AREA 25 1.750 12.1580 18.99

BB3 AREA 100 2.648 12.1580 28.33

C AREA 1 .606 12.2340 4.57

C AREA 2 .912 12.2040 7.87

C AREA 10 2.044 12.1740 20.20

C AREA 25 3.206 12.1740 32.93

C AREA 100 5.410 12.1730 56.67

DD AREA 1 .569 12.1380 6.11

DD AREA 2 .782 12.1370 8.69

DD AREA 10 1.512 12.1370 17.35

DD AREA 25 2.214 12.1370 25.49

DD AREA 100 3.485 12.1370 39.84

*DP 1 JCT 1 6.696 R 12.1590 31.31

*DP 1 JCT 2 9.850 R 12.4100 49.17

*DP 1 JCT 10 20.983 R 12.3360 169.48

*DP 1 JCT 25 31.968 R 12.2620 280.22

*DP 1 JCT 100 52.233 R 12.2360 459.05

EE AREA 1 .494 12.1190 5.68

EE AREA 2 .610 12.1190 6.95

EE AREA 10 .966 12.1190 10.77

EE AREA 25 1.280 12.1190 14.05

EE AREA 100 1.818 12.1190 19.55

S/N:




Name.... Watershed






Max



----------------- ---- ------ ---------- -- --------- -------- -------- ------------

FF AREA 1 .485 12.1090 6.10

FF AREA 2 .627 12.1090 7.86

FF AREA 10 1.083 12.1080 13.37

FF AREA 25 1.499 12.0990 18.25

FF AREA 100 2.227 12.0990 26.52

GG AREA 1 .436 12.1370 4.92

GG AREA 2 .579 12.1370 6.61

GG AREA 10 1.048 12.1370 12.06

GG AREA 25 1.486 12.1370 17.01

GG AREA 100 2.263 12.1370 25.53

JUNC 10 JCT 1 1.517 R 12.2360 13.51

JUNC 10 JCT 2 2.259 R 12.2360 21.69

JUNC 10 JCT 10 4.986 R 12.2020 49.01

JUNC 10 JCT 25 7.769 R 12.2010 71.29

JUNC 10 JCT 100 13.023 R 12.2010 109.44

JUNC A JCT 1 6.696 R 12.1590 31.31

JUNC A JCT 2 9.850 R 12.4100 49.17

JUNC A JCT 10 20.983 R 12.3360 169.48

JUNC A JCT 25 31.968 R 12.2620 280.22

JUNC A JCT 100 52.233 R 12.2360 459.05

JUNC D JCT 1 5.707 R 12.1380 29.08

JUNC D JCT 2 7.893 R 12.4200 43.36

JUNC D JCT 10 15.468 R 12.3270 112.93

JUNC D JCT 25 22.851 R 12.2900 176.82

JUNC D JCT 100 36.359 R 12.2360 282.97

JUNC E JCT 1 1.312 R 12.1180 16.55

JUNC E JCT 2 1.689 R 12.1180 21.24

JUNC E JCT 10 2.901 R 12.1160 35.93

JUNC E JCT 25 4.011 R 12.1160 48.96

JUNC E JCT 100 5.954 R 12.1100 71.15

S/N:




Name.... Watershed






Max



----------------- ---- ------ ---------- -- --------- -------- -------- ------------

JUNC F JCT 1 .849 R 12.1160 10.87

JUNC F JCT 2 1.116 R 12.1160 14.30

JUNC F JCT 10 1.989 R 12.1100 25.18

JUNC F JCT 25 2.799 R 12.1100 34.97

JUNC F JCT 100 4.229 R 12.1100 51.70

JUNC G JCT 1 .400 R 12.1370 4.92

JUNC G JCT 2 .533 R 12.1370 6.61

JUNC G JCT 10 .975 R 12.1370 12.06

JUNC G JCT 25 1.390 R 12.1370 17.01

JUNC G JCT 100 2.127 R 12.1370 25.53

POND AA-2 IN POND 1 1.661 R 12.2440 15.70

POND AA-2 IN POND 2 2.390 R 12.2440 23.77

POND AA-2 IN POND 10 4.985 R 12.2070 52.53

POND AA-2 IN POND 25 7.568 R 12.2070 80.61

POND AA-2 IN POND 100 12.359 R 12.2070 131.37

POND AA-2 OUT POND 1 1.494 R 16.4190 1.22 272.01 1.326

POND AA-2 OUT POND 2 2.211 R 13.1110 4.64 272.11 1.361

POND AA-2 OUT POND 10 4.776 R 12.3590 42.28 272.73 1.583

POND AA-2 OUT POND 25 7.338 R 12.2620 76.64 273.09 1.722

POND AA-2 OUT POND 100 12.097 R 12.2440 127.35 273.54 1.903

POND B IN POND 1 3.973 R 12.2050 39.11

POND B IN POND 2 5.612 R 12.2020 57.53

POND B IN POND 10 11.380 R 12.2010 118.93

POND B IN POND 25 17.072 R 12.2010 172.53

POND B IN POND 100 27.569 R 12.1850 265.84

POND B OUT POND 1 3.973 12.5900 18.11 280.97 .999

POND B OUT POND 2 5.612 12.5130 32.26 281.21 1.377

POND B OUT POND 10 11.380 12.3900 87.01 281.79 2.293

POND B OUT POND 25 17.071 12.3380 136.78 282.18 2.954

POND B OUT POND 100 27.568 12.3120 218.27 282.79 4.013

S/N:




Name.... Watershed






Max



----------------- ---- ------ ---------- -- --------- -------- -------- ------------

POND C IN POND 1 .531 R 12.2340 4.57

POND C IN POND 2 .810 R 12.2040 7.87

POND C IN POND 10 1.856 R 12.1740 20.20

POND C IN POND 25 2.939 R 12.1740 32.93

POND C IN POND 100 5.007 R 12.1730 56.67

POND C OUT POND 1 .531 12.2700 4.48 311.02 .008

POND C OUT POND 2 .810 12.2690 7.44 311.34 .020

POND C OUT POND 10 1.856 12.3150 16.25 312.16 .117

POND C OUT POND 25 2.939 12.4130 20.15 312.78 .352

POND C OUT POND 100 5.007 12.5090 24.36 313.60 1.005

S/N:



stormwater management report-2

Documents

existing conditions

proposed stormwater

proposed conditions

stormwater quantity

stormwater quality analysis

postdevelopment conditions

pace university mount

site characteristics