drainage report: cold harbor brewery 66 otis street

Drainage Report:

Cold Harbor Brewery 66 Otis Street

Westborough, Massachusetts

Submitted to:

Town of Westborough Planning Board

August 25, 2021

66 Otis Street Westborough, Massachusetts

STORM WATER MANAGEMENT DESIGN August 25, 2021

INTRODUCTION The project site is comprised of approximately 2.66 acres of land located in the Business Highway/Industrial at 66 Otis Street. The site currently has an existing single-family home and an existing detached garage on the property. The site is bound by Otis Street to the to the east and north, a commercial property to the west, and an industrial property to the south. Refer to Figure 1 for the Locus Plan. The proposed project includes the construction of an approximately 12,000 SF commercial building with associated site improvements. The roof runoff from the proposed structure will be collected by a roof leader system and conveyed to the proposed stormwater basin. The runoff from the pavement areas will drain to a series a catch basin and will be conveyed to the proposed stormwater basins.

The hydrologic study area is comprised of approximately 2.66 acres. Based on the USDA Natural Resources Conservation Service soil survey, the majority of the site is comprised of Merrimac fine sandy loam, which is a Hydrologic Soil Group (HSG) “A” Soil. Soil testing was conducted on site and it was found that the soils were consistently sandy loams and medium sands with high infiltrative capacities consistent with an “A” soil. Refer to Appendix A for the NRCS soil survey.

EXISTING CONDITIONS As described above, the site consists of a single-family home and detached garage. The site is comprised of 0.07 acres of rooftop, 0.05 acres of pavement, 0.013 acres of patio area, 2.44 acres of grass, and 0.09 acres of woods. The existing site is comprised of two watershed areas.

Area 1 includes front portion of the house and lot. This area sheet flows to Otis Street which is considered Point of Analysis 1 (POA-1).

Area 2 includes the remaining lot area. This area sheet flows to the wetland system west of the site, which is considered Point of Analysis 2 (POA-2). Refer to Figure 2- Existing Watershed Plan.

66 Otis Street Westborough, Massachusetts Storm Water Management Design

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PROPOSED CONDITIONS Under proposed conditions, the site is comprised of approximately 1.48 acres of grass, 0.72 acres of pavement, 0.033 acres of concrete, 0.27 acres of roof top and 0.16 acres of woods. The post-development peak run-off rates will be mitigated to meet the pre-development runoff rates for all design storm events through the use of at grade and below grade infiltration basin. The proposed site is comprised of 5 watershed areas.

Area 1 includes the parking field located along Otis Street and half of the parking field and drive aisle located to the south of the proposed building. This area sheet flows to the proposed catch basins and is conveyed through a pipe network to the proposed below grade infiltration basin. The basin discharges to the drainage network located in Otis Street, which is considered Point of Analysis 1 (POA-1).

Area 2 includes the remaining parking areas, the proposed building and the western portion of the grassed area. The proposed impervious area sheet flows to the proposed catch basin and trench drain and is conveyed through a piped network to the proposed at grade infiltration basin. The proposed pervious area sheet flows to the at grade infiltration basin. The proposed basin discharges to the wetland system, which is considered Point of Analysis 2 (POA-2).

Area 3 includes the grassed area located on the southern side of the parking area. This are sheet flows to POA-1.

Area 4 includes the grassed and wooded area located on the northern side of the site. This area sheet flows to POA-2.

Area 5 includes the grassed area between Otis Street and the parking field. This area sheet flows to POA-1. Refer to Figure 3 – Proposed Watershed Plan.

STORMWATER MANAGEMENT The proposed drainage design was based on the revised Massachusetts Department of Environmental Protection (MADEP) Stormwater Management Standards (Stormwater Policy). The standards have been revised to promote increased stormwater recharge, the treatment of more runoff from polluting land uses, pollution prevention, the removal of illicit discharges to stormwater management systems, and improved operation and maintenance of stormwater best management practices (BMP’s). The following summarizes the proposed project’s compliance with the revised Stormwater Management Standards.

Standard #1 Untreated Storm Water: No new storm water conveyances have been proposed to discharge untreated stormwater directly to or cause erosion in wetlands or waters of the Commonwealth. Stormwater Best Management Practices (BMP’s), such as deep sump catch basins, at grade infiltration basin, and below grade infiltration basin are


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proposed within the project to provide stormwater quality control prior to discharging runoff from the site.

Standard #2 Post-Development Peak Discharge Rates: As a result of the increase in net impervious area from existing to proposed conditions, storm water BMP’s have been developed to meet the peak discharge rates for the 2, 10, 25 and 100 year, 24-hour storm events. Refer to Table 1 for the pre- and post-development peak discharge rates.

Standard #3 Recharge to Groundwater: The project site is located within Hydrologic Soil Group (HSG) “A” classified soil. Per MA DEP standards, recharge is required to eliminate or minimize the loss of annual recharge to groundwater through the use of environmentally sensitive site design, BMP’s and good operation and maintenance. As the project will result in an increase in impervious area, and no infiltration BMP’s were present on the existing site, the entire impervious area of the development is being considered in the sizing of the proposed recharge facilities.

The required recharge volume for the proposed impervious area (1.04 ac) resulting from the project is 0.052 AC-FT. For the 2-year storm event, the below grade infiltration basin will provide approximately 0.085 AC-FT of recharge to groundwater and 0.06 AC-FT of recharge to the groundwater for the at grade infiltration basin. Refer to the HydroCAD model in Appendix B. In addition, the project will provide approximately 1,858 CF of volume (>1.0” water quality volume) below the outlet of the below grade infiltration basin and 5,375 CF of volume (>1.0” water quality volume) below the spillway for the at grade infiltration basin.

Because the basin is located within an “A” soil, the water quality volumes will draw down within 3 hours. Refer to Appendix A for the recharge calculations and drawdown analysis.

Standard #4 80 Percent TSS Removal: Based on the proposed stormwater management system design, the proposed BMP’s will remove in excess of the required 80% of the Total Suspended Solids (TSS) from the stormwater runoff discharging from the site. This is being achieved through the use of Deep Sump Catch Basins, Water Quality Units and At Grade and Below grade Infiltration Basin. The proposed BMP’s have also been sized to treat in excess of the required 1” water quality volume. The proposed Water Quality Units are providing an excess of 80% TSS removal prior to reaching the Infiltration Basins as required for sites with a rapid infiltration rate (>2.4 in/hr) Refer to Appendix A for the Water Quality Volume calculations and the TSS Removal Worksheet.

Standard #5 Higher Potential Pollutant Loads: The proposed project is not classified by the DEP as a source for higher pollutant loads.

Standard #6 Protection of Critical Areas: The project site is not considered a Critical Area as defined by MassDEP.


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Standard #7 Redevelopment Project: The project is new development.

Standard #8 Erosion/Sediment Control: Erosion and sediment controls are incorporated into the project design to prevent erosion, control sediment movement, and stabilize exposed soils during construction. During construction, control practices will be utilized such as the placement of straw wattle barriers, silt fencing, and the implementation of soil stabilization practices. These control measures will be periodically checked and maintained as necessary throughout the entire construction duration.

Standard #9 Operation/Maintenance Plan: A long term operation and maintenance plan has been developed to ensure the stormwater management system will function as designed. See Appendix A for the Operation and Maintenance Plan and Long-Term Pollution Prevention plan.

Standard #10 Illicit Discharges to Stormwater Management System: The Stormwater Management System associated with the development has been designed such that prior to storm water runoff discharging from the site, it is treated through a series of best management practices. To the Engineer’s knowledge, there are no known or designed non-storm water discharges that are or will be connected to the storm water collection system that would convey pollutants directly to groundwater or surface waters. See Appendix A for the Illicit Discharge Compliance Statement. The proposed design meets all applicable DEP Stormwater Management Standards. Refer to Appendix A for the MADEP Stormwater Checklist.

DRAINAGE COLLECTION SYSTEM DESIGN The proposed drain pipe network is composed of deep sump catch basins and manholes that will collect runoff from the parking and landscaped areas within the proposed development and convey it to the proposed infiltration basin. The pipe layout is depicted on the Grading and Drainage Plan in the plan set.

Pipe sizes were determined using the Rational Method to determine contributing flows to catch basins, as well as the Manning’s Equation to calculate pipe flows (refer to Appendix A for pipe sizing calculations.)

The following criteria were used to design the pipe network:

Manholes are provided at all changes in direction or changes in pipe size.

Pipe sizes are based on flows for the 25-year storm frequency.

Storm drain pipes shall be HDPE.

Pipe flow velocities are maintained at a maximum of 12 fps.


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STORMWATER QUANTITY Due to the proposed increase in impervious area, the project will require BMP’s for infiltration and detention in order to comply with Standards # 2 and #3 of the DEP Stormwater Management Policy. The stormwater facilities proposed will include an at grade and below grade infiltration basins. The proposed basins will recharge the required water quality volume in addition to attenuating the peak runoff rates for the 2, 10, 25 and 100-year, 24-hour storm events.

Hydrologic analyses were performed utilizing the computer program, HydroCAD©. In order to determine the peak rate of discharge for existing and proposed conditions, runoff hydrographs were generated for the 2-, 10-, 25- and 100-year, 24-hour storm events using the SCS TR-20 Method and Type III rainfall distribution (refer to Appendix B for the existing and proposed HydroCAD models). Under proposed conditions, the post development runoff hydrographs were flood routed through the proposed stormwater management facilities.

Table 1 compares peak runoff rates for the 2-, 10-, 25-, and 100-year storm events for existing and proposed conditions.

As shown in Table 1, peak runoff rates under proposed conditions are equal to or less than existing conditions for the 2-, 10-, 25- and 100-year storm events. Therefore, the proposed stormwater design complies with Standard #2 of the MA DEP Stormwater Management Policy.

STORMWATER QUALITY All stormwater runoff will be treated to address water quality concerns through the use of DEP approved BMP’s. The following BMP’s will be provided on-site and when combined will achieve in excess of 80% TSS removal: deep sump hooded catch basins, at grade infiltration basin. (See Appendix A for TSS Removal Worksheets)

Storm Event Existing Flow (cfs) Proposed Flow (cfs) Existing Flow (cfs) Proposed Flow (cfs)

POA-1 POA-1 POA-2 POA-2

2-Year 0.00 0.00 0.00 0.00

10-Year 0.11 0.03 0.04 0.00

25-Year 0.26 0.25 0.19 0.01

100-Year 0.61 0.61 0.64 0.64


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Deep Sump Catch Basins

The catch basins on the proposed site will be deep sump/hooded catch basins, which will serve to trap sediment and floatables before entering the drainage system. The sump will be four-feet deep. A hood will be provided with a vacuum-break to avoid siphoning of floatables out of the catch basin. Inlets in the catch basin should be cleaned a minimum of four times per year and inspected monthly. All sediments and hydrocarbons should be properly handled and disposed, in accordance with local, state, and federal guidelines and regulations.

Water Quality Unit

The proposed design of the on-site drainage system will incorporate a Stormceptor® unit prior to connecting to the at grade and below grade infiltration basin on site. Maintenance will be performed per the manufacturer’s recommendations; however basic maintenance will consist of monthly inspections and after each major storm event during the first year of installation to accurately establish the required maintenance schedule. The structures will be cleaned out twice per year or upon the stored volume reaching 15% of the particle separator’s capacity, or immediately in the event of a spill. Floatables and sediment will be removed through the 24-inch diameter outlet riser pipe and hydrocarbons will be removed through the 6-inch oil inspection port. Below grade Infiltration Basins Once constructed, infiltration basins will be inspected at a minimum after several storm events for the first year and annually thereafter to confirm drainage system functions as designed. Problems will be addressed immediately. System shall be cleaned as required per the manufacturer’s recommendations

At Grade Infiltration Basin

Once constructed, the infiltration basin will be inspected after several storm events to confirm drainage system functions, bank stability, and vegetation growth. Any problems will be addressed immediately. The basin will be inspected for proper operation at least once per year. Inspections will be conducted during wet weather to determine if the basin is functioning properly. At least twice during the growing season, the upper-stage, side slopes, embankment, and emergency spillway will be mowed. Accumulated trash and debris will be removed. Sediment will be removed from the basin as necessary, at least once every 10 years. CONCLUSION The proposed stormwater management plan for the project addresses both water quantity and quality issues, and conforms to the standards outlined in the revised MADEP Stormwater Management Policy.

Table of Contents INTRODUCTION ....................................................................................................... 1

EXISTING CONDITIONS .......................................................................................... 1

PROPOSED CONDITIONS ........................................................................................ 2

STORMWATER MANAGEMENT ............................................................................ 2

DRAINAGE COLLECTION SYSTEM DESIGN ...................................................... 4

STORMWATER QUANTITY .................................................................................... 4

STORMWATER QUALITY ....................................................................................... 5

CONCLUSION ............................................................................................................ 6

List of Tables Table 1 Comparison of Peak Runoff Rates .............................................. 5

List of Figures Figure 1 Locus Plan

Figure 2 Existing Watershed Plan

Figure 3 Proposed Watershed Plan

Appendix A NRCS Soil Survey

Recharge Calculations

Drawdown Analysis

Water Quality Volume & Flow Rate Calculations

TSS Removal Worksheets

Operation and Maintenance Plan

Long Term Pollution Prevention Plan

MADEP Stormwater Checklist

Pipe Sizing (Culverts) Calculations

Sediment Forebay Sizing Calculations

Illicit Discharge Compliance Statement

Appendix B

Existing Conditions HydroCAD Model Proposed Conditions HydroCAD Model

Figures

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SITE

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Site Locus Map 08/25/2021

Appendix A

NRCS Soil Survey

Hydrologic Soil Group—Worcester County, Massachusetts, Northeastern Part

Natural ResourcesConservation Service

Web Soil SurveyNational Cooperative Soil Survey

8/17/2021Page 1 of 4

4684

230

4684

250

4684

270

4684

290

4684

310

4684

330

4684

350

4684

370

4684

390

4684

230

4684

250

4684

270

4684

290

4684

310

4684

330

4684

350

4684

370

4684

390

281170 281190 281210 281230 281250 281270 281290 281310 281330 281350 281370 281390 281410 281430

281170 281190 281210 281230 281250 281270 281290 281310 281330 281350 281370 281390 281410

42° 16' 52'' N71

° 3

9' 1

4'' W

42° 16' 52'' N

71° 3

9' 2

'' W

42° 16' 46'' N

71° 3

9' 1

4'' W

42° 16' 46'' N

71° 3

9' 2

'' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 19N WGS840 50 100 200 300

Feet0 15 30 60 90

MetersMap Scale: 1:1,220 if printed on A landscape (11" x 8.5") sheet.

Soil Map may not be valid at this scale.

MAP LEGEND MAP INFORMATION

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

SoilsSoil Rating Polygons

A

A/D

B

B/D

C

C/D

D

Not rated or not available

Soil Rating LinesA

A/D

B

B/D

C

C/D

D


Soil Rating PointsA

A/D

B

B/D

C

C/D

D


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 1:20,000.

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: Worcester County, Massachusetts, Northeastern PartSurvey Area Data: Version 15, Jun 10, 2020

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

Date(s) aerial images were photographed: Jul 26, 2019—Oct 5, 2019

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.




8/17/2021Page 2 of 4

Hydrologic Soil Group

Map unit symbol Map unit name Rating Acres in AOI Percent of AOI

1 Water 0.2 6.6%

254A Merrimac fine sandy loam, 0 to 3 percent slopes

A 2.9 81.4%

254D Merrimac fine sandy loam, 15 to 25 percent slopes

A 0.4 11.9%

Totals for Area of Interest 3.5 100.0%

Description

Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms.

The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows:

Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission.

Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission.

Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission.

Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission.

If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes.




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Rating Options

Aggregation Method: Dominant Condition

Component Percent Cutoff: None Specified

Tie-break Rule: Higher




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Soil Testing Results

Recharge Calculations

McCarty Engineering, INC. Project: Cold HarborStormwater Recharge Date: 8/25/21

Comp: JLLCity: Westborough Check : BRMState: MA

Recharge Required

Hydrologic Soil Goup

Volume to Recharge (in)

A 0.6

Required Recharge Volume

Soil groupA 1.04 0.052

Total 0.052

Recharge Provided *Total Recharge Provided in Infiltration Basins during the 2-year storm= 0.145 AC-FT

*All recharge is taking place through the bottom of the infiltration basins. Refer to the ProposedConditions HydroCAD Model for the Recharge Volume for all storm events.

Required Volume (ac-ft)

Impervious Area (ac)

P:\MEI\206-Alexander\Drainage\2021-08-18 Recharge Infiltration Basins .xls

Drawdown Analysis

McCarty Engineering, INC. Project: Cold Harbor Proj. No: 206Drawdown Analysis Date: 8/25/21

City: Westborough Comp: JLLState: MA Check : BRM

At Grade Infiltration BasinStorage Volume Below the Outlet = 5,375 CFHydraulic Conductivity for a Sand = 2.41 in/hr (Rawls Rate)

Drawdown Time = Storage Volume/(Saturated Hydraulic Conductivity x Bottom Area)

Drawdown Time Silt Loam = 1,776 cf/(2.41in/hr(1ft/12in)(4,286 sf))

Dt = 2.1 hours

P:\MEI\206-Alexander\Drainage\2021-08-25 Drawdown Analysis At Grade Basin .xls

McCarty Engineering, INC. Project: Cold Harbor Proj. No: 206Drawdown Analysis Date: 8/25/21


Underground Infiltration BasinStorage Volume Below the Outlet = 1,776 CFHydraulic Conductivity for a Sand = 2.41 in/hr (Rawls Rate)

Drawdown Time = Storage Volume/(Saturated Hydraulic Conductivity x Bottom Area)

Drawdown Time Silt Loam = 1,858 cf/(2.41in/hr(1ft/12in)(2,105.2 sf))

Dt = 2.2 hours

P:\MEI\206-Alexander\Drainage\2021-08-25 Drawdown Analysis Underground Basin 1.xls

Water Quality Volume & Flow Rate Calculations

Type III 24-hr 100-Year Rainfall=6.50"2021-08-17 Proposed Printed 8/23/2021Prepared by {enter your company name here}

HydroCAD® 10.00-22 s/n 02034 © 2018 HydroCAD Software Solutions LLC

Stage-Area-Storage for Pond 1P: Underground Basin (continued)

Elevation(feet)

Surface(sq-ft)

Storage(cubic-feet)

304.56 2,105 1,379304.57 2,105 1,395304.58 2,105 1,412304.59 2,105 1,429304.60 2,105 1,446304.61 2,105 1,462304.62 2,105 1,479304.63 2,105 1,496304.64 2,105 1,512304.65 2,105 1,529304.66 2,105 1,545304.67 2,105 1,562304.68 2,105 1,579304.69 2,105 1,595304.70 2,105 1,612304.71 2,105 1,628304.72 2,105 1,645304.73 2,105 1,661304.74 2,105 1,678304.75 2,105 1,694304.76 2,105 1,711304.77 2,105 1,727304.78 2,105 1,743304.79 2,105 1,760304.80 2,105 1,776304.81 2,105 1,792304.82 2,105 1,809304.83 2,105 1,825304.84 2,105 1,841304.85 2,105 1,858304.86 2,105 1,874304.87 2,105 1,890304.88 2,105 1,906304.89 2,105 1,923304.90 2,105 1,939304.91 2,105 1,955304.92 2,105 1,971304.93 2,105 1,987304.94 2,105 2,003304.95 2,105 2,019304.96 2,105 2,035304.97 2,105 2,052304.98 2,105 2,068304.99 2,105 2,084305.00 2,105 2,100305.01 2,105 2,116305.02 2,105 2,131305.03 2,105 2,147305.04 2,105 2,163305.05 2,105 2,179305.06 2,105 2,195305.07 2,105 2,211305.08 2,105 2,227

Elevation(feet)

Surface(sq-ft)

Storage(cubic-feet)

305.09 2,105 2,243305.10 2,105 2,258305.11 2,105 2,274305.12 2,105 2,290305.13 2,105 2,305305.14 2,105 2,321305.15 2,105 2,337305.16 2,105 2,352305.17 2,105 2,368305.18 2,105 2,383305.19 2,105 2,399305.20 2,105 2,415305.21 2,105 2,430305.22 2,105 2,446305.23 2,105 2,461305.24 2,105 2,476305.25 2,105 2,492305.26 2,105 2,507305.27 2,105 2,522305.28 2,105 2,538305.29 2,105 2,553305.30 2,105 2,568305.31 2,105 2,584305.32 2,105 2,599305.33 2,105 2,614305.34 2,105 2,629305.35 2,105 2,644305.36 2,105 2,659305.37 2,105 2,674305.38 2,105 2,690305.39 2,105 2,705305.40 2,105 2,720305.41 2,105 2,734305.42 2,105 2,749305.43 2,105 2,764305.44 2,105 2,779305.45 2,105 2,794305.46 2,105 2,809305.47 2,105 2,824305.48 2,105 2,838305.49 2,105 2,853305.50 2,105 2,868305.51 2,105 2,882305.52 2,105 2,897305.53 2,105 2,912305.54 2,105 2,926305.55 2,105 2,941305.56 2,105 2,955305.57 2,105 2,970305.58 2,105 2,984305.59 2,105 2,999305.60 2,105 3,013305.61 2,105 3,027

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Water Quality Volume Calculation-Underground Basin

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Outlet Invert =

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WQv Provided

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WQv Required=1.0in x Area Inp. sf x 1ft/12in

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WQv Required=1.0in x 16,138 sf x 1ft/12in =1,344.83 cf

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1,858 cf > 1,344.83 cf



Stage-Area-Storage for Pond 3P: Above Ground Basin (continued)

Elevation(feet)

Surface(sq-ft)

Storage(cubic-feet)

304.06 5,467 5,155304.07 5,483 5,209304.08 5,499 5,264304.09 5,515 5,319304.10 5,530 5,375304.11 5,546 5,430304.12 5,562 5,486304.13 5,578 5,541304.14 5,593 5,597304.15 5,609 5,653304.16 5,625 5,709304.17 5,641 5,766304.18 5,656 5,822304.19 5,672 5,879304.20 5,688 5,936304.21 5,704 5,993304.22 5,719 6,050304.23 5,735 6,107304.24 5,751 6,164304.25 5,767 6,222304.26 5,782 6,280304.27 5,798 6,338304.28 5,814 6,396304.29 5,829 6,454304.30 5,845 6,512304.31 5,861 6,571304.32 5,877 6,629304.33 5,892 6,688304.34 5,908 6,747304.35 5,924 6,806304.36 5,940 6,866304.37 5,955 6,925304.38 5,971 6,985304.39 5,987 7,045304.40 6,003 7,105304.41 6,018 7,165304.42 6,034 7,225304.43 6,050 7,285304.44 6,066 7,346304.45 6,081 7,407304.46 6,097 7,468304.47 6,113 7,529304.48 6,129 7,590304.49 6,144 7,651304.50 6,160 7,713304.51 6,176 7,774304.52 6,191 7,836304.53 6,207 7,898304.54 6,223 7,960304.55 6,239 8,023304.56 6,254 8,085304.57 6,270 8,148304.58 6,286 8,211

Elevation(feet)

Surface(sq-ft)

Storage(cubic-feet)

304.59 6,302 8,274304.60 6,317 8,337304.61 6,333 8,400304.62 6,349 8,463304.63 6,365 8,527304.64 6,380 8,591304.65 6,396 8,654304.66 6,412 8,718304.67 6,428 8,783304.68 6,443 8,847304.69 6,459 8,912304.70 6,475 8,976304.71 6,491 9,041304.72 6,506 9,106304.73 6,522 9,171304.74 6,538 9,236304.75 6,554 9,302304.76 6,569 9,368304.77 6,585 9,433304.78 6,601 9,499304.79 6,616 9,565304.80 6,632 9,632304.81 6,648 9,698304.82 6,664 9,765304.83 6,679 9,831304.84 6,695 9,898304.85 6,711 9,965304.86 6,727 10,032304.87 6,742 10,100304.88 6,758 10,167304.89 6,774 10,235304.90 6,790 10,303304.91 6,805 10,371304.92 6,821 10,439304.93 6,837 10,507304.94 6,853 10,576304.95 6,868 10,644304.96 6,884 10,713304.97 6,900 10,782304.98 6,916 10,851304.99 6,931 10,920305.00 6,947 10,990

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Water Quality Volume Calculation-At Grade Basin

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Outlet Invert =

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WQv Provided

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WQv Required=1.0in x Area Inp. sf x 1ft/12in

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WQv Required=1.0in x 29,036 sf x 1ft/12in =2,419.67 cf

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5,375 cf > 2,419.67 cf

McCarty Engineering, INC. Project: Cold Harbor Proj. No: 206Date: 8/25/21


Converting WQv to Fow Rate for Sizing Proprietary Stormwater Treatemnnt Practices

Required WQv = 1.0 inch

Q0.5=(qu)(A)(WQv)

qu = Unit Peak Discharge in csm/in - This Variable derived from MADEP Flow rate table, Figure 2 (attached).A = Impervious Area in square miles (sm) - 1 ac = 0.0015625 sm

WQv= Water Quality Volume in watershed inches (1.0 in)

Structure

WQU1 Tc= 5 minutes = 0.083 hoursqu= 795 csm/inA= 0.33ac = 0.000515 sm

WQv= 1.0 in

Flow Rate= ( 795 csm/in)x(0.000515 sm)x(1.0 in)Flow Rate= 0.409

P:\MEI\206-Alexander\Drainage\2021-08-20 WQU1 WQV to Q Calculation.xls

McCarty Engineering, INC. Project: Cold Harbor Proj. No: 206Date: 8/25/21


Converting WQv to Fow Rate for Sizing Proprietary Stormwater Treatemnnt Practices

Required WQv = 1.0 inch

Q0.5=(qu)(A)(WQv)

qu = Unit Peak Discharge in csm/in - This Variable derived from MADEP Flow rate table, Figure 2 (attached).A = Impervious Area in square miles (sm) - 1 ac = 0.0015625 sm

WQv= Water Quality Volume in watershed inches (1.0 in)

Structure

WQU 2 Tc= 5 minutes = 0.083 hoursqu= 795 csm/inA= 0.67ac = 0.00104 sm

WQv= 1.0 in

Flow Rate= ( 795 csm/in)x(0.00104 sm)x(1.0 in)Flow Rate= 0.827

P:\MEI\206-Alexander\Drainage\2021-08-20 WQU2 WQV to Q Calculation.xls

TSS Removal Worksheets

V

INSTRUCTIONS: Version 1, Automated: Mar. 4, 2008

1. In BMP Column, click on Blue Cell to Activate Drop Down Menu2. Select BMP from Drop Down Menu3. After BMP is selected, TSS Removal and other Columns are automatically completed.

Location:

B C D E FTSS Removal Starting TSS Amount Remaining

BMP1 Rate1Load* Removed (C*D) Load (D-E)

Deep Sump and Hooded Catch Basin 0.25 1.00 0.25 0.75

Water Quality Unit 0.80 0.75 0.60 0.15

Infiltration Basin 0.80 0.15 0.12 0.03

0.00 0.03 0.00 0.03

0.00 0.03 0.00 0.03

Total TSS Removal = 97%

Separate Form Needs to be Completed for Each Outlet or BMP Train

Project: Cold Harboar

Prepared By: JLL *Equals remaining load from previous BMP (E)

Date: 8/25/2021 which enters the BMP

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Above Ground Infiltration Basin

Non-automated TSS Calculation Sheetmust be used if Proprietary BMP Proposed1. From MassDEP Stormwater Handbook Vol. 1 Mass. Dept. of Environmental Protection

V

INSTRUCTIONS: Version 1, Automated: Mar. 4, 2008

1. In BMP Column, click on Blue Cell to Activate Drop Down Menu2. Select BMP from Drop Down Menu3. After BMP is selected, TSS Removal and other Columns are automatically completed.

Location:

B C D E FTSS Removal Starting TSS Amount Remaining

BMP1 Rate1Load* Removed (C*D) Load (D-E)

Deep Sump and Hooded Catch Basin 0.25 1.00 0.25 0.75

Water Quality Unit 0.80 0.75 0.60 0.15

Infiltration Basin 0.80 0.15 0.12 0.03

0.00 0.03 0.00 0.03

0.00 0.03 0.00 0.03

Total TSS Removal = 97%

Separate Form Needs to be Completed for Each Outlet or BMP Train

Project: Cold Harboar

Prepared By: JLL *Equals remaining load from previous BMP (E)

Date: 8/25/2021 which enters the BMP

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Underground Infiltration Basin

Non-automated TSS Calculation Sheetmust be used if Proprietary BMP Proposed1. From MassDEP Stormwater Handbook Vol. 1 Mass. Dept. of Environmental Protection

Project Information & LocationProject Name Cold Harbor Project Number 39189

City Westborough State/ Province Massachusetts

Country United States of America Date 8/20/2021

Designer Information EOR Information (optional)

Name Justin LeClair Name

Company McCarty Engineering Company

Phone # 978-534-1318 Phone #

Email [email protected] Email

Brief Stormceptor Sizing Report - Water Quality Unit 1

Site Name Water Quality Unit 1

Target TSS Removal (%) 80

TSS Removal (%) Provided 83

Recommended Stormceptor Model STC 450i

Stormceptor Sizing SummaryStormceptor Model % TSS Removal

Provided

STC 450i 83

STC 900 88

STC 1200 88

STC 1800 89

STC 2400 91

STC 3600 91

STC 4800 93

STC 6000 93

STC 7200 95

STC 11000 96

STC 13000 96

STC 16000 97

The recommended Stormceptor Model achieves the water quality objectives based on the selected inputs, historical rainfall records and selected particle size distribution.

Stormwater Treatment Recommendation The recommended Stormceptor Model(s) which achieve or exceed the user defined water quality objective for each site within the project are listed in the below Sizing Summary table.

Stormceptor Brief Sizing Report – Page 1 of 2

Notes• Stormceptor performance estimates are based on simulations using PCSWMM for Stormceptor, which uses the EPA Rainfall and Runoff modules.• Design estimates listed are only representative of specific project requirements based on total suspended solids (TSS) removal defined by the selected PSD, and based on stable site conditions only, after construction is completed.• For submerged applications or sites specific to spill control, please contact your local Stormceptor representative for further design assistance.

Drainage Area

Total Area (acres) 0.33

Imperviousness % 92.0

Water Quality Objective

TSS Removal (%) 80.0

Runoff Volume Capture (%)

Oil Spill Capture Volume (Gal)

Peak Conveyed Flow Rate (CFS)

Water Quality Flow Rate (CFS) 0.41

Rainfall

Station Name WORCESTER WSO AP

State/Province Massachusetts

Station ID # 9923

Years of Records 58

Latitude 42°16'2"N

Longitude 71°52'34"W

Up Stream Storage

Storage (ac-ft) Discharge (cfs)

0.000 0.000

Particle Size Distribution (PSD)The selected PSD defines TSS removal

Fine Distribution

Particle Diameter(microns)

Distribution %

Specific Gravity

20.0 20.0 1.30

60.0 20.0 1.80

150.0 20.0 2.20

400.0 20.0 2.65

2000.0 20.0 2.65

Up Stream Flow Diversion

Max. Flow to Stormceptor (cfs)

Sizing Details

For Stormceptor Specifications and Drawings Please Visit: https://www.conteches.com/technical-guides/search?filter=1WBC0O5EYX


Project Information & LocationProject Name Cold Harbor Project Number 39189

City Westborough State/ Province Massachusetts

Country United States of America Date 8/20/2021

Designer Information EOR Information (optional)

Name Justin LeClair Name

Company McCarty Engineering Company

Phone # 978-534-1318 Phone #

Email [email protected] Email

Brief Stormceptor Sizing Report - Water Quality Unit 2

Site Name Water Quality Unit 2

Target TSS Removal (%) 80

TSS Removal (%) Provided 82

Recommended Stormceptor Model STC 450i

Stormceptor Sizing SummaryStormceptor Model % TSS Removal

Provided

STC 450i 82

STC 900 88

STC 1200 88

STC 1800 88

STC 2400 91

STC 3600 91

STC 4800 93

STC 6000 93

STC 7200 95

STC 11000 96

STC 13000 96

STC 16000 97

The recommended Stormceptor Model achieves the water quality objectives based on the selected inputs, historical rainfall records and selected particle size distribution.

Stormwater Treatment Recommendation The recommended Stormceptor Model(s) which achieve or exceed the user defined water quality objective for each site within the project are listed in the below Sizing Summary table.


Notes• Stormceptor performance estimates are based on simulations using PCSWMM for Stormceptor, which uses the EPA Rainfall and Runoff modules.• Design estimates listed are only representative of specific project requirements based on total suspended solids (TSS) removal defined by the selected PSD, and based on stable site conditions only, after construction is completed.• For submerged applications or sites specific to spill control, please contact your local Stormceptor representative for further design assistance.

Drainage Area

Total Area (acres) 0.72

Imperviousness % 93.0

Water Quality Objective

TSS Removal (%) 80.0

Runoff Volume Capture (%)

Oil Spill Capture Volume (Gal)

Peak Conveyed Flow Rate (CFS)

Water Quality Flow Rate (CFS) 0.83

Rainfall

Station Name WORCESTER WSO AP

State/Province Massachusetts

Station ID # 9923

Years of Records 58

Latitude 42°16'2"N

Longitude 71°52'34"W

Up Stream Storage

Storage (ac-ft) Discharge (cfs)

0.000 0.000

Particle Size Distribution (PSD)The selected PSD defines TSS removal

Fine Distribution

Particle Diameter(microns)

Distribution %

Specific Gravity

20.0 20.0 1.30

60.0 20.0 1.80

150.0 20.0 2.20

400.0 20.0 2.65

2000.0 20.0 2.65

Up Stream Flow Diversion

Max. Flow to Stormceptor (cfs)

Sizing Details

For Stormceptor Specifications and Drawings Please Visit: https://www.conteches.com/technical-guides/search?filter=1WBC0O5EYX




The site contractor will be responsible for the operation and maintenance of the stormwater collection system including deep sump catch basins and an at grade infiltration basin during construction. After construction, the Property Owner is responsible for the operation and maintenance of the proposed stormwater collection system. The following long-term Operation and Maintenance Plan for the project is proposed in accordance with DEP Stormwater Management Standard No. 9 to ensure that the stormwater collection and treatment system operates in accordance with the MADEP Stormwater Management Policy.

Schedule for Inspection and Maintenance after Construction:

Stormwater Management System Owner/Operator The property owner will be the owner and operator of the proposed stormwater collection

system on site. If the property is sold, a copy of this Operation and Maintenance Plan will be transferred

to the new property owners.

Deep Sump Catch Basins Inlets should be cleaned a minimum of four times per year and inspected monthly.

All sediments and hydrocarbons should be properly handled and disposed, in accordance with local, state, and federal guidelines and regulations.

Structures should be inspected and maintained according to the manufacturer’s recommendation.

Water Quality Unit

Structure cover should be inspected monthly for evidence of repair. Verify that inverts are secure and free flowing. Measure depth of sediment below water line.

Unit shall be cleaned a minimum of twice per year. One of these cleanings to occur before April 15th of each year and one shall occur before September 15th of each year. Unite must be cleaned with a vacuum pump.

All liquid, sediment, and hydrocarbons shall be pumped from the sump at least twice per year at intervals corresponding with the unit cleaning.

All sediment, water and hydrocarbons should be properly handled and disposed of in accordance with local, state and federal guidelines and regulations.

Refer to water quality unit manufacturers specifications for additional maintenance recommendations.

Below Grade Infiltration Basin

Once constructed, basins will be inspected at a minimum after several storm events for the first year and annually thereafter to confirm drainage system functions as designed. Problems will be addressed immediately.

System shall be cleaned as required per the manufacturer’s recommendations.


Once constructed, the basin will be inspected at a minimum after several storm events to confirm drainage system functions, bank stability, and vegetation growth. Problems will be addressed immediately.

During the first six months of operation, the basin will be inspected immediately after significant storm events and cleaned to remove sediment buildup.

The outlet structure will be inspected and repaired where sediment appears to have clogged the invert.

A stake shall be placed at the bottom of the pond with marks at 1” increments to measure the sediment accumulation. Sediment will be removed from ponds at a minimum when accumulation is at 4”, but as often as necessary, and at least once every 10 years.

At least twice during the growing season, the side slopes will be mowed, and accumulated trash and debris removed. Accumulated sediment in forebay will also be removed at this time

The routine and non-routine maintenance tasks to be undertaken after construction and a schedule for implementing those task A site maintenance log will be kept. This log will record the dates when maintenance

tasks were completed, the person who completed the task, and any observations of

malfunctions in components of the stormwater management system. A sample maintenance log form is attached.

Estimated Operations and Maintenance Budget Operation and maintenance costs for the project are expected to be approximately

$5,000/year



Operation and Maintenance Schedule

BMP Frequency Date Performed

Comments Cleaning/Repair Needed? Yes/No

Date of Cleaning/ Repair

Performed By

Catch Basins Monthly Inspections Quarterly cleaning

Water Quality Unit

Monthly Inspections Biannual Cleaning

Below Grade Infiltration Basins

Inspection after each major storm event for the first year Cleaning as needed


Annual Inspections and after each major storm event. Banks mowed twice a year. Cleaning as needed (Min once every 10 years)

Site Maintenance Supervisor: Date:

SSAAMMPPLLEE

Long Term Pollution Prevention Plan

Cold Harbor Brewery 66 Otis Street

Westborough, Massachusetts Long Term Pollution Prevention Plan

A long-term pollution prevention plan is an important element of the routine operation and maintenance of an industrial facility that is designed to reduce or eliminate the creation of pollutants at the source. In addition to the obvious environmental benefits of protecting the natural resources downstream of the facility, maintaining a long-term pollution prevention plan will provide for a healthier and safer work environment. The following long term pollution prevention practices will be employed at the facility.

• Good housekeeping practices:

Maintaining a clean property will prevent or reduce the amount of pollutants in the stormwater runoff discharging from the site. This will be achieved through periodic parking lot sweeping, at the owner’s discretion, and through catch basin and infiltration basin cleaning as detailed within the sites Stormwater Operation and Maintenance Plan.

• Provisions for storing materials and waste products inside or under cover:

Materials will be stored in their appropriate containers and shall be stored under cover or in a secure enclosure to reduce the risk of spills. Waste products will be placed in proper bins until emptied by a licensed solid waste management company.

• Requirements for routine inspections and maintenance of stormwater BMPs: Refer to the maintenance schedule provided in the Stormwater Operation and Maintenance Plan.

• Spill prevention and response plans: Materials shall be stored in their proper original container in a secure location. No mixing of materials shall occur unless recommended by manufacturer. The manufacturer’s recommendations for proper use and disposal should be strictly adhered to. In the case of a spill the manufacturer’s method for cleanup shall be followed. The area shall be kept ventilated and personnel handling the cleanup shall wear proper protective clothing. Spills of toxic or hazardous material shall be reported to the appropriate State and/or local authority in accordance with local and/or State regulations.

• Provisions for maintenance of lawns, gardens, and other landscaped areas: Owner will maintain surrounding landscaped area as needed.

• Provisions for solid waste management: Solid waste material shall be placed in outdoor secure containers until emptied by licensed waste management company.

• Snow disposal and plowing plans relative to Wetland Resource Areas: Snow shall be placed on upland areas only where sand and debris will remain after snowmelt for later removal. Snow shall be plowed in accordance with standard operating procedures and stored in designated areas as detailed on the site plan approval

documents. Any sand and debris remaining after snow piles have melted will be removed by the facility owners or maintenance contractors.

• Winter Road Salt/or Sand Use and Storage restriction: The use of environmentally friendly alternatives to road salt will be considered.

• Provisions for prevention of illicit discharges to the stormwater management system: The Stormwater Management System associated with the development has been designed such that prior to storm water runoff discharging from the site, it is treated through a series of best management practices. To the Engineer’s knowledge, there are no known or designed non-storm water discharges that are or will be connected to the storm water collection system that would convey pollutants directly to groundwater or surface waters.

• Documentation that Stormwater BMPs are designed to provide for shutdown and containment in the event of a spill or discharges to a near critical areas or from LUHPPL: All catch basins shall be equipped with hoods to prevent oils and floatables from discharging to the underground detention/infiltration basins.

• Training for staff or personnel involved with the implementing Long Term Pollution Prevention Plan: Facilities staff will be responsible for implementing the Long-Term Pollution Prevention Plan and staff will be trained in accordance with company policy.

• List of Emergency contacts for implementing Long-Term Pollution Prevention Plan: William Oliveira 504 Green Street Northborough, MA 01532 (508) 768-5232

MADEP Stormwater Checklist

2021-08-25 stormwater checklist.doc • 04/01/08 Stormwater Report Checklist • Page 3 of 8

Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program

Checklist for Stormwater Report

Checklist (continued) LID Measures: Stormwater Standards require LID measures to be considered. Document what

environmentally sensitive design and LID Techniques were considered during the planning and design of the project:

No disturbance to any Wetland Resource Areas

Site Design Practices (e.g. clustered development, reduced frontage setbacks)

Reduced Impervious Area (Redevelopment Only)

Minimizing disturbance to existing trees and shrubs

LID Site Design Credit Requested:

Credit 1

Credit 2

Credit 3

Use of “country drainage” versus curb and gutter conveyance and pipe

Bioretention Cells (includes Rain Gardens)

Constructed Stormwater Wetlands (includes Gravel Wetlands designs)

Treebox Filter

Water Quality Swale

Grass Channel

Green Roof

Other (describe):

Standard 1: No New Untreated Discharges

No new untreated discharges Outlets have been designed so there is no erosion or scour to wetlands and waters of the

Commonwealth

Supporting calculations specified in Volume 3 of the Massachusetts Stormwater Handbook included.




Checklist (continued)

Standard 2: Peak Rate Attenuation Standard 2 waiver requested because the project is located in land subject to coastal storm flowage

and stormwater discharge is to a wetland subject to coastal flooding. Evaluation provided to determine whether off-site flooding increases during the 100-year 24-hour

storm.

Calculations provided to show that post-development peak discharge rates do not exceed pre-development rates for the 2-year and 10-year 24-hour storms. If evaluation shows that off-site flooding increases during the 100-year 24-hour storm, calculations are also provided to show that post-development peak discharge rates do not exceed pre-development rates for the 100-year 24-hour storm.

Standard 3: Recharge

Soil Analysis provided.

Required Recharge Volume calculation provided.

Required Recharge volume reduced through use of the LID site Design Credits.

Sizing the infiltration, BMPs is based on the following method: Check the method used.

Static Simple Dynamic Dynamic Field1

Runoff from all impervious areas at the site discharging to the infiltration BMP.

Runoff from all impervious areas at the site is not discharging to the infiltration BMP and calculations

are provided showing that the drainage area contributing runoff to the infiltration BMPs is sufficient to generate the required recharge volume.

Recharge BMPs have been sized to infiltrate the Required Recharge Volume.

Recharge BMPs have been sized to infiltrate the Required Recharge Volume only to the maximum extent practicable for the following reason:

Site is comprised solely of C and D soils and/or bedrock at the land surface

M.G.L. c. 21E sites pursuant to 310 CMR 40.0000

Solid Waste Landfill pursuant to 310 CMR 19.000

Project is otherwise subject to Stormwater Management Standards only to the maximum extent practicable.

Calculations showing that the infiltration BMPs will drain in 72 hours are provided.

Property includes a M.G.L. c. 21E site or a solid waste landfill and a mounding analysis is included.

1 80% TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used.





Standard 3: Recharge (continued)

The infiltration BMP is used to attenuate peak flows during storms greater than or equal to the 10-year 24-hour storm and separation to seasonal high groundwater is less than 4 feet and a mounding analysis is provided.

Documentation is provided showing that infiltration BMPs do not adversely impact nearby wetland resource areas.

Standard 4: Water Quality

The Long-Term Pollution Prevention Plan typically includes the following: • Good housekeeping practices; • Provisions for storing materials and waste products inside or under cover; • Vehicle washing controls; • Requirements for routine inspections and maintenance of stormwater BMPs; • Spill prevention and response plans; • Provisions for maintenance of lawns, gardens, and other landscaped areas; • Requirements for storage and use of fertilizers, herbicides, and pesticides; • Pet waste management provisions; • Provisions for operation and management of septic systems; • Provisions for solid waste management; • Snow disposal and plowing plans relative to Wetland Resource Areas; • Winter Road Salt and/or Sand Use and Storage restrictions; • Street sweeping schedules; • Provisions for prevention of illicit discharges to the stormwater management system; • Documentation that Stormwater BMPs are designed to provide for shutdown and containment in the

event of a spill or discharges to or near critical areas or from LUHPPL; • Training for staff or personnel involved with implementing Long-Term Pollution Prevention Plan; • List of Emergency contacts for implementing Long-Term Pollution Prevention Plan.

A Long-Term Pollution Prevention Plan is attached to Stormwater Report and is included as an attachment to the Wetlands Notice of Intent.

Treatment BMPs subject to the 44% TSS removal pretreatment requirement and the one inch rule for calculating the water quality volume are included, and discharge:

is within the Zone II or Interim Wellhead Protection Area

is near or to other critical areas

is within soils with a rapid infiltration rate (greater than 2.4 inches per hour)

involves runoff from land uses with higher potential pollutant loads.

The Required Water Quality Volume is reduced through use of the LID site Design Credits.

Calculations documenting that the treatment train meets the 80% TSS removal requirement and, if applicable, the 44% TSS removal pretreatment requirement, are provided.





Standard 4: Water Quality (continued)

The BMP is sized (and calculations provided) based on:

The ½” or 1” Water Quality Volume or The equivalent flow rate associated with the Water Quality Volume and documentation is

provided showing that the BMP treats the required water quality volume.

The applicant proposes to use proprietary BMPs, and documentation supporting use of proprietary BMP and proposed TSS removal rate is provided. This documentation may be in the form of the propriety BMP checklist found in Volume 2, Chapter 4 of the Massachusetts Stormwater Handbook and submitting copies of the TARP Report, STEP Report, and/or other third party studies verifying performance of the proprietary BMPs.

A TMDL exists that indicates a need to reduce pollutants other than TSS and documentation showing that the BMPs selected are consistent with the TMDL is provided.

Standard 5: Land Uses With Higher Potential Pollutant Loads (LUHPPLs)

The NPDES Multi-Sector General Permit covers the land use and the Stormwater Pollution

Prevention Plan (SWPPP) has been included with the Stormwater Report.

The NPDES Multi-Sector General Permit covers the land use and the SWPPP will be submitted prior to the discharge of stormwater to the post-construction stormwater BMPs.

The NPDES Multi-Sector General Permit does not cover the land use.

LUHPPLs are located at the site and industry specific source control and pollution prevention measures have been proposed to reduce or eliminate the exposure of LUHPPLs to rain, snow, snow melt and runoff, and been included in the long term Pollution Prevention Plan.

All exposure has been eliminated.

All exposure has not been eliminated and all BMPs selected are on MassDEP LUHPPL list.

The LUHPPL has the potential to generate runoff with moderate to higher concentrations of oil and grease (e.g. all parking lots with >1000 vehicle trips per day) and the treatment train includes an oil grit separator, a filtering bioretention area, a sand filter or equivalent.

Standard 6: Critical Areas

The discharge is near or to a critical area and the treatment train includes only BMPs that MassDEP has approved for stormwater discharges to or near that particular class of critical area.

Critical areas and BMPs are identified in the Stormwater Report.





Standard 7: Redevelopments and Other Projects Subject to the Standards only to the maximum extent practicable

The project is subject to the Stormwater Management Standards only to the maximum Extent Practicable as a:

Limited Project

Small Residential Projects: 5-9 single family houses or 5-9 units in a multi-family development provided there is no discharge that may potentially affect a critical area.

Small Residential Projects: 2-4 single family houses or 2-4 units in a multi-family development with a discharge to a critical area

Marina and/or boatyard provided the hull painting, service and maintenance areas are protected from exposure to rain, snow, snow melt and runoff

Bike Path and/or Foot Path

Redevelopment Project

Redevelopment portion of mix of new and redevelopment.

Certain standards are not fully met (Standard No. 1, 8, 9, and 10 must always be fully met) and an explanation of why these standards are not met is contained in the Stormwater Report.

The project involves redevelopment and a description of all measures that have been taken to improve existing conditions is provided in the Stormwater Report. The redevelopment checklist found in Volume 2 Chapter 3 of the Massachusetts Stormwater Handbook may be used to document that the proposed stormwater management system (a) complies with Standards 2, 3 and the pretreatment and structural BMP requirements of Standards 4-6 to the maximum extent practicable and (b) improves existing conditions.

Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control

A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan must include the following information:

• Narrative; • Construction Period Operation and Maintenance Plan; • Names of Persons or Entity Responsible for Plan Compliance; • Construction Period Pollution Prevention Measures; • Erosion and Sedimentation Control Plan Drawings; • Detail drawings and specifications for erosion control BMPs, including sizing calculations; • Vegetation Planning; • Site Development Plan; • Construction Sequencing Plan; • Sequencing of Erosion and Sedimentation Controls; • Operation and Maintenance of Erosion and Sedimentation Controls; • Inspection Schedule; • Maintenance Schedule; • Inspection and Maintenance Log Form.

A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan containing the information set forth above has been included in the Stormwater Report.





Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control (continued)

The project is highly complex and information is included in the Stormwater Report that explains why it is not possible to submit the Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan with the application. A Construction Period Pollution Prevention and Erosion and Sedimentation Control has not been included in the Stormwater Report but will be submitted before land disturbance begins.

The project is not covered by a NPDES Construction General Permit.

The project is covered by a NPDES Construction General Permit and a copy of the SWPPP is in the Stormwater Report.

The project is covered by a NPDES Construction General Permit but no SWPPP been submitted. The SWPPP will be submitted BEFORE land disturbance begins.

Standard 9: Operation and Maintenance Plan

The Post Construction Operation and Maintenance Plan is included in the Stormwater Report and includes the following information:

Name of the stormwater management system owners;

Party responsible for operation and maintenance;

Schedule for implementation of routine and non-routine maintenance tasks;

Plan showing the location of all stormwater BMPs maintenance access areas;

Description and delineation of public safety features;

Estimated operation and maintenance budget; and

Operation and Maintenance Log Form.

The responsible party is not the owner of the parcel where the BMP is located and the Stormwater Report includes the following submissions:

A copy of the legal instrument (deed, homeowner’s association, utility trust or other legal entity) that establishes the terms of and legal responsibility for the operation and maintenance of the project site stormwater BMPs;

A plan and easement deed that allows site access for the legal entity to operate and maintain BMP functions.

Standard 10: Prohibition of Illicit Discharges

The Long-Term Pollution Prevention Plan includes measures to prevent illicit discharges;

An Illicit Discharge Compliance Statement is attached;

NO Illicit Discharge Compliance Statement is attached but will be submitted prior to the discharge of any stormwater to post-construction BMPs.

Pipe Sizing (Culvert) Calculations

McCarty Engineering, Inc. Project: Cold Harbor Proj. No: 206Culvert Flows 66 Otis Street Date: 8/25/21


*Shaded columns indicate input values

Culvert AREA C AREA C COMPOSITE C TOTAL AREA TOTAL AREA QID (sq. ft) FACTOR (sq. ft) FACTOR (sq. ft) (acres) (CFS)

CB 1 2925 0.9 74 0.3 0.89 2999 0.07 0.4CB 2 5412 0.9 526 0.3 0.85 5938 0.14 0.7CB 3 7803 0.9 514 0.3 0.86 8317 0.19 1.0CB 4 15046 0.9 1000 0.3 0.86 16046 0.37 2.0RL 1 12112 0.9 0 0.3 0.90 12112 0.28 1.6TD 1 1878 0.9 1240 1.3 1.06 3118 0.07 0.5

Paved Unpaved

P:\MEI\206-Alexander\Drainage\2021-08-20 CB Flows.xls

Pipe Design WorksheetProject # /Name: Cold Harbor

66 Otis StreetCalculated By: JLL Date: 8/25/2021

Checked By: BRM Date: 8/25/2021

n= 0.01 HDPE Pipe

Culvert Q Qsum Length Slope Dia. Full-Flow Velocity(ID, Lot #) (cfs) (cfs) (ft.) (ft./ft.) (in.) (fps)

CB 1 to DMH 1 0.40 77.3 0.01 12 5.91 4.64 O.KCB 2 to DMH 1 0.70 53.4 0.01 12 5.91 4.64 O.K

DMH 1 to WQU 1 1.10 1.10 21.0 0.01 12 5.91 4.64 O.KCB 3 to WQU 1 1.00 24.0 0.01 12 5.91 4.64 O.K

WQU 1 to DMH 2 2.10 2.10 21.0 0.01 12 5.91 4.64 O.KOCS 1* to DMH 3 0.23 81.5 0.01 12 5.91 4.64 O.K

TD 1 to DMH 4 0.50 68.6 0.01 12 5.91 4.64 O.KRL to DMH 4 1.60 192.0 0.01 12 5.91 4.64 O.K

DMH 4 to WQU 2 2.10 2.10 83.5 0.01 12 5.91 4.64 O.KCB 4 to WQU 2 2.00 34.6 0.01 12 5.91 4.64 O.K

WQU 2 to FES 1 4.10 4.10 19.0 0.01 12 5.91 4.64 O.K* Flows form the 25-year storm event from HydroCAD were utilized

Full-Flow Capacity2

(cfs)

1 V=1.49/n x R2/3 x S 1/2

2 Q=VA

Sediment Forebay Sizing Calculations



Summary for Pond 7P: Forebay

[43] Hint: Has no inflow (Outflow=Zero)

Volume Invert Avail.Storage Storage Description#1 304.00' 355 cf Custom Stage Data (Prismatic) Listed below (Recalc)

Elevation Surf.Area Inc.Store Cum.Store(feet) (sq-ft) (cubic-feet) (cubic-feet)

304.00 0 0 0305.00 293 147 147305.50 539 208 355

bmarchetti

Text Box

INFILTRATION BASIN - SEDIMENT FOREBAY SIZING CALCULATION

bmarchetti

Typewritten Text

Tributary Impervious Area to Forebay 1 = 28,044 SF Forebay 1 Required Volume = 28,044 SF X 0.1 in X (1 ft/12 in) = 233.7 cf

bmarchetti

Rectangle

Illicit Discharge Compliance Statement


Illicit Discharge Compliance Statement The Stormwater Management System associated with the development of 66 Otis Street has been designed such that prior to storm water runoff discharging from the site, it is treated through a series of best management practices. To the Engineer’s knowledge, there are no known or designed non-storm water discharges that are or will be connected to the storm water collection system that would convey pollutants directly to groundwater or surface waters.

Name: Brian Marchetti, P.E. Title: Vice President

Signature:

Date:

08/25/2021

Appendix B

Existing Conditions HydroCAD Model

1S

Area 1

2S

Area 2

POA-1

Otis Street

POA-2

Existing Wetland

Routing Diagram for 2021-08-17 ExistingPrepared by {enter your company name here}, Printed 8/23/2021


Subcat Reach Pond Link

2021-08-17 Existing Printed 8/23/2021Prepared by {enter your company name here}

Page 2HydroCAD® 10.00-22 s/n 02034 © 2018 HydroCAD Software Solutions LLC

Project Notes

Rainfall events imported from "TP-40-Rain.txt" for 449 MA Worcester



Area Listing (all nodes)

Area(acres)

CN Description(subcatchment-numbers)

2.441 39 >75% Grass cover, Good, HSG A (1S, 2S)0.013 98 Brick Patio, HSG A (1S, 2S)0.049 98 Paved parking, HSG A (1S)0.069 98 Roofs, HSG A (1S, 2S)0.090 30 Woods, Good, HSG A (2S)

2.663 42 TOTAL AREA



Soil Listing (all nodes)

Area(acres)

SoilGroup

SubcatchmentNumbers

2.663 HSG A 1S, 2S0.000 HSG B0.000 HSG C0.000 HSG D0.000 Other

2.663 TOTAL AREA



Ground Covers (all nodes)

HSG-A(acres)

HSG-B(acres)

HSG-C(acres)

HSG-D(acres)

Other(acres)

Total(acres)

GroundCover

SubcatchmentNumbers

2.441 0.000 0.000 0.000 0.000 2.441 >75% Grass cover, Good 1S, 2S0.013 0.000 0.000 0.000 0.000 0.013 Brick Patio 1S, 2S0.049 0.000 0.000 0.000 0.000 0.049 Paved parking 1S0.069 0.000 0.000 0.000 0.000 0.069 Roofs 1S, 2S0.090 0.000 0.000 0.000 0.000 0.090 Woods, Good 2S

2.663 0.000 0.000 0.000 0.000 2.663 TOTAL AREA

Type III 24-hr 2-Year Rainfall=3.00"2021-08-17 Existing Printed 8/23/2021Prepared by {enter your company name here}


Time span=0.00-24.00 hrs, dt=0.01 hrs, 2401 pointsRunoff by SCS TR-20 method, UH=SCS, Weighted-CN

Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method

Runoff Area=24,963 sf 15.98% Impervious Runoff Depth>0.06"Subcatchment 1S: Area 1 Flow Length=167' Slope=0.0200 '/' Tc=7.7 min CN=48 Runoff=0.00 cfs 0.003 af

Runoff Area=91,035 sf 1.93% Impervious Runoff Depth=0.00"Subcatchment 2S: Area 2 Flow Length=263' Slope=0.0100 '/' Tc=12.6 min CN=40 Runoff=0.00 cfs 0.000 af

Inflow=0.00 cfs 0.003 afReach POA-1: Otis Street Outflow=0.00 cfs 0.003 af

Inflow=0.00 cfs 0.000 afReach POA-2: Existing Wetland Outflow=0.00 cfs 0.000 af

Total Runoff Area = 2.663 ac Runoff Volume = 0.003 af Average Runoff Depth = 0.01"95.05% Pervious = 2.531 ac 4.95% Impervious = 0.132 ac



Summary for Subcatchment 1S: Area 1

Runoff = 0.00 cfs @ 14.98 hrs, Volume= 0.003 af, Depth> 0.06"

Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsType III 24-hr 2-Year Rainfall=3.00"

Area (sf) CN Description1,367 98 Roofs, HSG A2,154 98 Paved parking, HSG A

* 468 98 Brick Patio, HSG A20,974 39 >75% Grass cover, Good, HSG A24,963 48 Weighted Average20,974 84.02% Pervious Area

3,989 15.98% Impervious Area

Tc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)

5.7 50 0.0200 0.15 Sheet Flow, Grass: Short n= 0.150 P2= 3.10"

2.0 117 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps

7.7 167 Total




[45] Hint: Runoff=Zero

Runoff = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Depth= 0.00"


Area (sf) CN Description1,655 98 Roofs, HSG A

* 101 98 Brick Patio, HSG A85,375 39 >75% Grass cover, Good, HSG A

3,904 30 Woods, Good, HSG A91,035 40 Weighted Average89,279 98.07% Pervious Area





12.6 263 Total



Summary for Reach POA-1: Otis Street

[40] Hint: Not Described (Outflow=Inflow)

Inflow Area = 0.573 ac, 15.98% Impervious, Inflow Depth > 0.06" for 2-Year eventInflow = 0.00 cfs @ 14.98 hrs, Volume= 0.003 afOutflow = 0.00 cfs @ 14.98 hrs, Volume= 0.003 af, Atten= 0%, Lag= 0.0 min

Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs



Summary for Reach POA-2: Existing Wetland


Inflow Area = 2.090 ac, 1.93% Impervious, Inflow Depth = 0.00" for 2-Year eventInflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 afOutflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min













7.7 167 Total













12.6 263 Total












7.7 167 Total













12.6 263 Total












7.7 167 Total













12.6 263 Total

Proposed Conditions HydroCAD Model

1S

Area 1

2S

Area 23S

Area 3

4S

Area 4

5S

Area 5

POA-1

Otis Street

POA-2

Existing Wetland

1P

Underground Basin

3P

At Grade Basin

Routing Diagram for 2021-08-17 ProposedPrepared by {enter your company name here}, Printed 8/27/2021


Subcat Reach Pond Link

2021-08-17 Proposed Printed 8/27/2021Prepared by {enter your company name here}


Project Notes

Rainfall events imported from "TP-40-Rain.txt" for 449 MA Worcester



Area Listing (all nodes)

Area(acres)

CN Description(subcatchment-numbers)

1.488 39 >75% Grass cover, Good, HSG A (1S, 2S, 3S, 4S, 5S)0.033 98 Concrete, HSG A (1S, 2S)0.726 98 Paved parking, HSG A (1S, 2S)0.278 98 Roofs, HSG A (2S)0.161 30 Woods, Good, HSG A (4S)

2.686 61 TOTAL AREA



Soil Listing (all nodes)

Area(acres)

SoilGroup

SubcatchmentNumbers

2.686 HSG A 1S, 2S, 3S, 4S, 5S0.000 HSG B0.000 HSG C0.000 HSG D0.000 Other

2.686 TOTAL AREA



Ground Covers (all nodes)

HSG-A(acres)

HSG-B(acres)

HSG-C(acres)

HSG-D(acres)

Other(acres)

Total(acres)

GroundCover

SubcatchmentNumbers

1.488 0.000 0.000 0.000 0.000 1.488 >75% Grass cover, Good 1S, 2S, 3S, 4S, 5S

0.033 0.000 0.000 0.000 0.000 0.033 Concrete 1S, 2S0.726 0.000 0.000 0.000 0.000 0.726 Paved parking 1S, 2S0.278 0.000 0.000 0.000 0.000 0.278 Roofs 2S0.161 0.000 0.000 0.000 0.000 0.161 Woods, Good 4S

2.686 0.000 0.000 0.000 0.000 2.686 TOTAL AREA



Pipe Listing (all nodes)

Line# NodeNumber

In-Invert(feet)

Out-Invert(feet)

Length(feet)

Slope(ft/ft)

n Diam/Width(inches)

Height(inches)

Inside-Fill(inches)

1 1P 304.00 303.19 81.5 0.0099 0.012 12.0 0.0 0.0





Runoff Area=17,262 sf 93.50% Impervious Runoff Depth>2.35"Subcatchment 1S: Area 1 Tc=5.0 min CN=94 Runoff=1.09 cfs 0.078 af


Runoff Area=10,037 sf 0.00% Impervious Runoff Depth=0.00"Subcatchment 3S: Area 3 Flow Length=117' Slope=0.0100 '/' Tc=9.1 min CN=39 Runoff=0.00 cfs 0.000 af

Runoff Area=21,268 sf 0.00% Impervious Runoff Depth=0.00"Subcatchment 4S: Area 4 Flow Length=89' Tc=8.1 min CN=36 Runoff=0.00 cfs 0.000 af

Runoff Area=4,750 sf 0.00% Impervious Runoff Depth=0.00"Subcatchment 5S: Area 5 Tc=5.0 min CN=39 Runoff=0.00 cfs 0.000 af



Peak Elev=304.39' Storage=1,092 cf Inflow=1.09 cfs 0.078 afPond 1P: Underground Basin Discarded=0.15 cfs 0.077 af Primary=0.00 cfs 0.000 af Outflow=0.15 cfs 0.077 af

Peak Elev=303.10' Storage=450 cf Inflow=0.66 cfs 0.066 afPond 3P: At Grade Basin Discarded=0.25 cfs 0.066 af Primary=0.00 cfs 0.000 af Outflow=0.25 cfs 0.066 af







Area (sf) CN Description15,163 98 Paved parking, HSG A

* 977 98 Concrete, HSG A1,122 39 >75% Grass cover, Good, HSG A

17,262 94 Weighted Average1,122 6.50% Pervious Area



5.0 Direct Entry,







* 443 98 Concrete, HSG A34,637 39 >75% Grass cover, Good, HSG A63,673 66 Weighted Average34,637 54.40% Pervious Area29,036 45.60% Impervious Area




8.0 103 Total







Area (sf) CN Description10,037 39 >75% Grass cover, Good, HSG A10,037 100.00% Pervious Area




9.1 117 Total







Area (sf) CN Description14,257 39 >75% Grass cover, Good, HSG A





0.3 25 0.3300 1.44 Shallow Concentrated Flow, Forest w/Heavy Litter Kv= 2.5 fps

8.1 89 Total









5.0 Direct Entry,



Summary for Pond 1P: Underground Basin

Inflow Area = 0.396 ac, 93.50% Impervious, Inflow Depth > 2.35" for 2-Year eventInflow = 1.09 cfs @ 12.07 hrs, Volume= 0.078 afOutflow = 0.15 cfs @ 12.58 hrs, Volume= 0.077 af, Atten= 86%, Lag= 30.3 minDiscarded = 0.15 cfs @ 12.58 hrs, Volume= 0.077 afPrimary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af

Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsPeak Elev= 304.39' @ 12.58 hrs Surf.Area= 2,105 sf Storage= 1,092 cf

Plug-Flow detention time= 52.5 min calculated for 0.077 af (100% of inflow)Center-of-Mass det. time= 52.0 min ( 839.9 - 787.8 )

Volume Invert Avail.Storage Storage Description#1A 303.50' 1,918 cf 34.75'W x 60.58'L x 3.50'H Field A

7,368 cf Overall - 2,573 cf Embedded = 4,795 cf x 40.0% Voids#2A 304.00' 2,573 cf ADS_StormTech SC-740 +Cap x 56 Inside #1

Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cfOverall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap7 Rows of 8 Chambers

4,491 cf Total Available Storage

Storage Group A created with Chamber Wizard

Device Routing Invert Outlet Devices#1 Primary 304.00' 12.0" Round CPP_Round 12"

L= 81.5' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 304.00' / 303.19' S= 0.0099 '/' Cc= 0.900 n= 0.012 Corrugated PP, smooth interior, Flow Area= 0.79 sf

#2 Discarded 303.50' 2.410 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 300.00'

#3 Device 1 304.85' 6.0" Vert. Orifice/Grate C= 0.600

Discarded OutFlow Max=0.15 cfs @ 12.58 hrs HW=304.39' (Free Discharge)2=Exfiltration ( Controls 0.15 cfs)

Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=303.50' (Free Discharge)1=CPP_Round 12" ( Controls 0.00 cfs)

3=Orifice/Grate ( Controls 0.00 cfs)



Pond 1P: Underground Basin - Chamber Wizard Field A

Chamber Model = ADS_StormTech SC-740 +Cap (ADS StormTech® SC-740 with cap length)Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cfOverall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap

51.0" Wide + 6.0" Spacing = 57.0" C-C Row Spacing

8 Chambers/Row x 7.12' Long +0.81' Cap Length x 2 = 58.58' Row Length +12.0" End Stone x 2 = 60.58' Base Length7 Rows x 51.0" Wide + 6.0" Spacing x 6 + 12.0" Side Stone x 2 = 34.75' Base Width6.0" Base + 30.0" Chamber Height + 6.0" Cover = 3.50' Field Height

56 Chambers x 45.9 cf = 2,572.6 cf Chamber Storage

7,367.6 cf Field - 2,572.6 cf Chambers = 4,795.0 cf Stone x 40.0% Voids = 1,918.0 cf Stone Storage

Chamber Storage + Stone Storage = 4,490.6 cf = 0.103 afOverall Storage Efficiency = 61.0%Overall System Size = 60.58' x 34.75' x 3.50'

56 Chambers272.9 cy Field177.6 cy Stone



Summary for Pond 3P: At Grade Basin


Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsPeak Elev= 303.10' @ 12.55 hrs Surf.Area= 4,399 sf Storage= 450 cf


Volume Invert Avail.Storage Storage Description#1 303.00' 10,990 cf Custom Stage Data (Prismatic) Listed below (Recalc)


303.00 4,286 0 0304.00 5,373 4,830 4,830305.00 6,947 6,160 10,990

Device Routing Invert Outlet Devices#1 Primary 304.10' 20.0' long x 10.0' breadth Broad-Crested Rectangular Weir

Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64



Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=303.00' (Free Discharge)1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)








Runoff Area=21,268 sf 0.00% Impervious Runoff Depth>0.05"Subcatchment 4S: Area 4 Flow Length=89' Tc=8.1 min CN=36 Runoff=0.00 cfs 0.002 af





Peak Elev=303.53' Storage=2,444 cf Inflow=2.09 cfs 0.170 afPond 3P: At Grade Basin Discarded=0.29 cfs 0.169 af Primary=0.00 cfs 0.000 af Outflow=0.29 cfs 0.169 af












5.0 Direct Entry,











8.0 103 Total










9.1 117 Total












8.1 89 Total








5.0 Direct Entry,

















Primary OutFlow Max=0.03 cfs @ 12.67 hrs HW=304.94' (Free Discharge)1=CPP_Round 12" (Passes 0.03 cfs of 2.01 cfs potential flow)

3=Orifice/Grate (Orifice Controls 0.03 cfs @ 1.04 fps)









303.00 4,286 0 0304.00 5,373 4,830 4,830305.00 6,947 6,160 10,990
















5.0 Direct Entry,











8.0 103 Total










9.1 117 Total












8.1 89 Total








5.0 Direct Entry,









303.00 4,286 0 0304.00 5,373 4,830 4,830305.00 6,947 6,160 10,990
















5.0 Direct Entry,











8.0 103 Total










9.1 117 Total












8.1 89 Total








5.0 Direct Entry,









303.00 4,286 0 0304.00 5,373 4,830 4,830305.00 6,947 6,160 10,990





Primary OutFlow Max=0.58 cfs @ 12.59 hrs HW=304.15' (Free Discharge)1=Broad-Crested Rectangular Weir (Weir Controls 0.58 cfs @ 0.56 fps)

drainage report: cold harbor brewery 66 otis street

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