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HomeMy WebLinkAboutStorm Water Report 20230223revStormwater Report FOR COLBEA ENTERPRISES, LLC 473, 479 & 487 Station Ave, Yarmouth, MA Prepared By: 31 Hayward Street, Ste. E-1 Phone: 508-528-0770 Garrett Small, P.E. Date: 02/23/2023 HFA Project No. 42-21-20002 GARRETT DAVID PROF ESSIONA L E N G INEERCOMMONWEA L T H OF MASS A C HUSETTSRE GIS T E R EDSMALL CIVIL No. 58083 Table of Contents Summary… ......................................................................................................................... 2 Stormwater Management… ................................................................................................ 2 Massachusetts Stormwater Management Standards Analysis… ........................................ 4 Existing Watershed Plan… ................................................................................................. 7 Proposed Watershed Plan… ............................................................................................... 9 StormTech Isolator Row Sizing… .................................................................................... 11 Soil Evaluation Report… .................................................................................................. 13 Existing HydroCAD Calculations…................................................................................. 24 Proposed HydroCAD Calculations… ............................................................................... 55 Operation and Maintenance Plan… ................................................................................ 101 SUMMARY The project site consists of Map 97, Lot 1 & Lot 2, both N/F Jeanne L. Luby & Karen J. Luby-Drew, and a portion of Map 97, Lot 3 N/F Station Ave. LLC, and is located on the southern side of Station Avenue in Yarmouth, MA. The total area of the combined lots is 51,262 SF (1.18 Acres), and is predominantly an undeveloped Pitch Pine forest, with 601 SF of pavement encroachment from the abutter to the west. The proposed project includes the construction of a new 3,600 s.f. Seasons Corner Market with basement, a new 3,648 s.f. overhead canopy with 6 new fuel dispensing islands with diesel product, 2 new 15k underground, double walled fiberglass storage tanks with associated utility, grading, storm water, landscaping and curbing improvements. Twenty-eight (28) parking stalls, including two handicap, are proposed to serve the retail fueling facility. There are no wetlands, floodplain areas, agricultural uses, or historical cemeteries on or immediately adjacent to, the subject property. The subject property is zoned B-1 Business District, and is also in the Aquifer Protection Overlay District. STORMWATER MANAGEMENT The existing project area has no stormwater management components, with the rear third of the site sloping toward the abutter to the east, which contains abandoned railroad tracks. The front two thirds of the site flows to two depressed areas on site which retain and infiltrate stormwater. The proposed stormwater management system design consists of two Bioretention Areas with 1,500 gallon oil/grit separators, and two subsurface infiltration chamber systems using ADS Stormtech MC-4500 chambers, with treatment provided by Isolator Rows. The proposed condition will collect and treat runoff prior to discharge. A concrete curb along the edge of the pavement separating the paved areas of the site from the landscape areas will help convey runoff to the proposed on-site drainage system. The soil onsite is a 252A Carver coarse sand soil map unit. The NRCS Custom Soil Resource Report is attached for reference. A total of eight (8) test pits were dug onsite on November 29, 2018 to evaluate the soil suitability for infiltration of stormwater runoff, as well as for septic system design. The soil evaluation was performed by Edward J. Avizinis of Natural Resource Services, Inc. The soil was very consistent in all holes. All test pits revealed soils with an HSG of A, coarse sand types of soils. The saturated hydraulic conductivity of the least transmissive layer should be 8.27 in/hr, and no indication of the SHWT was encountered, with a test pipe at the front of the site dry to a depth of 16’ at least. The soil evaluation report is attached for reference. The proposed drainage system has been designed and sized to reduce total site peak runoff rates, for all storm events. The following chart provides a summary of the storm events, and comparison between the existing and proposed site conditions. Storm Event Existing Conditions Proposed Conditions To Street To Abutter Total To Street To Abutter Total 2 Year 0.00 0.00 0.00 0.00 0.00 0.00 10 Year 0.00 0.09 0.09 0.00 0.00 0.00 25 Year 0.00 0.31 0.31 0.00 0.01 0.01 100 Year 0.00 0.92 0.92 0.00 0.08 0.08 Drainage Calculations In support of the above analysis, calculations performed with HydroCAD 10.00 for the 2 year, 10 year, 25 year, and 100-year storm events are attached. The calculations clearly illustrate that there will be no net increase in runoff rates due to the proposed development, and in fact rates will be decreased for all storm events. MASS DOT STORMWATER STATEMENT There will be no increase in discharge of stormwater runoff to any MASS DOT state drainage system as a result of the proposed site improvements with this project. Massachusetts Stormwater Management Standards Analysis The Stormwater system for the proposed project was designed to meet the current standards of the Mass DEP Stormwater Management Policy, specifically Standard 5 for construction of retail motor fuel facility. LID: The site development has been minimized as much as possible, and two Bioretention Areas are proposed for natural stormwater treatment. Standard 1: There are no new untreated discharges. Standard 2: Calculations demonstrate that post development peak flows do not exceed pre-development peak flows. Off-site flooding for the 100 year event was not analyzed, however post development peak discharge rates do not exceed pre-development rates and it is assumed that no increased off-site flooding impacts are caused by the proposed development. Standard 3: Groundwater Recharge: Pavement infiltration is provided where no infiltration presently exists, increasing overall site recharge from existing conditions. Recharge = .60 inches of runoff x total impervious area (Hydrologic Group A) Recharge = (.60) x 34,606 SF/12 Recharge = 1,730 CF The volume of the infiltration systems is 11,769 C.F., which exceeds the 1,730 C.F. required. Draw Down Time: The infiltration systems have been designed to exfiltrate in less than 72 hours with a basin floor as flat as possible to provide a uniform ponding and exfiltration of runoff. Chamber system #1 Soil perc rate = 8.27 in/hr = 0.69 ft/hr Chamber field floor area = 764 S.F. Storage Volume (100 year storm) = 3,169 C.F. Exfiltration depth = Storage volume / Chamber field floor area Exfiltration depth = 3,169 C.F. / 764 S.F. = 4.15 ft. Time of exfiltration = exfiltration depth / soil perc rate = 4.15 ft / 0.69 ft/ hr = 6.01 hrs Chamber system #2 Soil perc rate = 8.27 in/hr = 0.69 ft/hr Chamber field floor area = 842 S.F. Basin Volume (100 year storm) = 3,508 C.F. Exfiltration depth = Storage volume / Chamber field floor area Exfiltration depth = 3,508 C.F. / 842 S.F. = 4.17 ft. Time of exfiltration = exfiltration depth / soil perc rate = 4.17 ft / 0.69 ft/ hr = 6.04 hrs Bioretention Area #1 Soil perc rate = 8.27 in/hr = 0.69 ft/hr Basin area = 2,642 S.F. Basin Volume (100 year storm) = 3,806 C.F. Exfiltration depth = Storage volume / Chamber field floor area Exfiltration depth = 3,806 C.F. /2,642 S.F.=1.44 ft. Time of exfiltration = exfiltration depth / soil perc rate = 1.44 ft / 0.69 ft/ hr = 2.09 hrs Bioretention Area #2 Soil perc rate = 8.27 in/hr = 0.69 ft/hr Basin area = 916 S.F. Basin Volume (100 year storm) = 1,301 C.F. Exfiltration depth = Storage volume / Chamber field floor area Exfiltration depth = 916 C.F. /1,301 S.F.=.70 ft. Time of exfiltration = exfiltration depth / soil perc rate = .70 ft / 0.69 ft/ hr = 1.01 hrs Standard 4: Deep sump catch basins will provide 25% TSS removal prior a secondary treatment consisting of a 1,500 gallon oil/grit separator for all of the sites pavement runoff. Additionally, filter fabric wrapped isolator row as part of a subsurface infiltration system will also provide treatment prior to infiltration. Water Quality Volume: WQv = (1”) (I)/12 WQv = 34,606/12 WQv = 2,884 CF The volume of the infiltration systems is 11,769 C.F., which exceeds the 2,884 C.F. required. Oil / Grit Separator Sizing Provide pool storage in the first chamber to accommodate the required water quality volume or 400 cubic feet per acre of impervious surface. Oil / Grit separator #1 (1,500 gal.) I = 1,789 S.F. = 0.04 Acre Vreq= 400 C.F/acre x 0.04 acre = 16.0 C.F Volume of the first chamber = B x W x H = 3 x 5 x 3.5 = 52.5 C.F The Volume of the first chamber is 52.5 C.F., which exceeds the required 16.0 C.F. Oil / Grit separator #2 (1,500 gal.) I = 5,869 S.F. = 0.13 Acre Vreq= 400 C.F/acre x 0.13 acre = 52.0 C.F Volume of the first chamber = B x W x H = 3 x 5 x 3.5 = 52.5 C.F The Volume of the first chamber is 52.5 C.F., which exceeds the required 52.0 C. Isolator Row Sizing The isolator rows have been sized using an isolator row sizing chart which has been provided by ADS Stormtech. In order to size the isolator row adequately, it is necessary to determine the flow rate generated by the water quality volume. Attached is the isolator row sizing chart as a reference. The results of the calculations are as follows. Chamber System #1- (8) MC-4500 WQf = 0.11 CFS Treated flow rate per chamber = 0.17 CFS Total treatment flow rate = (No. chambers) X (treated flow rate per chamber) Total Treatment flow rate = 8 X 0.17 = 1.36 CFS The Total treatment flow rate is 1.36 CFS, which exceeds the required 0.11 CFS. Chamber System #2- (9) MC-4500 WQf = 0.27 CFS Treated flow rate per chamber = 0.24 CFS Total treatment flow rate = (No. chambers) X (treated flow rate per chamber) Total Treatment flow rate = 9 X 0.17 = 1.53 CFS The Total treatment flow rate is 1.53 CFS, which exceeds the required 0.27 CFS. Standard 5: The proposed site is a multi-use retail and motor fuel facility. The operator of the motor fuel facility is trained to respond to small spills and there are response materials stored on site. Standard 6: The site does not contain any Critical Areas. Standard 7: The proposed work is not considered redevelopment due to the existing impervious area size. Standard 8: The project duration is expected to be less than four months. An Erosion Control Plan is part of the storm water package and a SWPPP will be prepared and maintained on site by the General Contractor throughout the duration of the construction. Typical measures to be employed during construction include sedimentation control by compost filter sock/silt fencing and truck exit controls. Standard 9: An Operation and Maintenance Plan is submitted as part of this storm water plan. Standard 10: Illicit Discharge Compliance Statement: This statement reflects the commitment of both the owner and operator of the subject facility to fully comply with the Massachusetts Stormwater Handbook Minimum Standard 10 - that there presently does not exist and that there will be NO ILLICIT DISCHARGES at this facility. An illicit discharge is defined as any discharge not entirely comprised of stormwater that are not specifically authorized by a National Pollutant Discharge Elimination System (NPDES) or permit. The property owner is ultimately responsible for the maintenance of all on-site drainage structures as defined in the Stormwater Operation and Maintenance Plan and as further detailed in the approved site plan and related stormwater drainage study. The future property owner Colbea Enterprises, LLC intends to manage maintenance and operations. The site is serviced by an OWTS that is not connected in any way with the stormwater system which will be verified during construction and documented on the as-built construction plan. Stormwater structures to be installed at the site include: piping between the roof areas and the associated underground infiltration system, oil/grit separators after a deep sump catch basin with hooded outlet to Bioretention Areas. There are no other discharges at the site. EXISTING WATERSHED PLAN 8 9 PROPOSED WATERSHED PLAN 10 STORMTECH ISOLATOR ROW SIZING 12 STORMTECH ISOLATOR ROW SIZING CHART SC-310 SC-740 DC-780 MC-3500 MC-4500 Chamber Area (Sq.Ft.) 20 27.8 27.8 43.2 30.1 Treated Flow Rate per chamber (CFS) 0.11 0.15 0.15 0.24 0.17 NOTE: Testing of the Isolator Row completed by Tennesse Tech has been verified by NJCAT and it has shown to have a TSS removal efficiency of 84% for SIL-CO-SIL 250 NJCAT verified Treated Flow Rate (GPM / Sq.Ft.) 2.5 13 SOIL EVALUATION REPORT 14 United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Barnstable County, MassachusettsNatural Resources Conservation Service November 9, 2018 15 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 16 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 17 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map (487 Station Ave)...................................................................................9 Legend................................................................................................................10 Map Unit Legend (487 Station Ave)....................................................................11 Map Unit Descriptions (487 Station Ave)............................................................11 Barnstable County, Massachusetts.................................................................13 252A—Carver coarse sand, 0 to 3 percent slopes......................................13 252B—Carver coarse sand, 3 to 8 percent slopes......................................14 252C—Carver coarse sand, 8 to 15 percent slopes...................................15 484D—Plymouth-Barnstable complex, hilly, extremely bouldery................16 602—Urban land.........................................................................................18 References............................................................................................................20 4 18 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5 19 scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and Custom Soil Resource Report 6 20 identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. Custom Soil Resource Report 7 21 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 22 9 Custom Soil Resource Report Soil Map (487 Station Ave)461540046155004615600461570046158004615900461540046155004615600461570046158004615900398800 398900 399000 399100 399200 399300 399400 399500 399600 399700 398800 398900 399000 399100 399200 399300 399400 399500 399600 399700 41° 41' 20'' N 70° 12' 57'' W41° 41' 20'' N70° 12' 15'' W41° 41' 0'' N 70° 12' 57'' W41° 41' 0'' N 70° 12' 15'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 19N WGS84 0 200 400 800 1200 Feet 0 50 100 200 300 Meters Map Scale: 1:4,430 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. 23 MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:25,000. 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 Service Web 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: Barnstable County, Massachusetts Survey Area Data: Version 15, Sep 5, 2018 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Dec 31, 2009—Mar 22, 2017 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. Custom Soil Resource Report 10 24 Map Unit Legend (487 Station Ave) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 252A Carver coarse sand, 0 to 3 percent slopes 38.3 39.9% 252B Carver coarse sand, 3 to 8 percent slopes 35.4 36.9% 252C Carver coarse sand, 8 to 15 percent slopes 3.9 4.0% 484D Plymouth-Barnstable complex, hilly, extremely bouldery 0.6 0.6% 602 Urban land 17.8 18.5% Totals for Area of Interest 95.9 100.0% Map Unit Descriptions (487 Station Ave) The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. Custom Soil Resource Report 11 25 The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 12 26 Barnstable County, Massachusetts 252A—Carver coarse sand, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 98qc Elevation: 0 to 1,000 feet Mean annual precipitation: 37 to 50 inches Mean annual air temperature: 45 to 55 degrees F Frost-free period: 120 to 240 days Farmland classification: Not prime farmland Map Unit Composition Carver and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Carver Setting Landform: Outwash plains Landform position (two-dimensional): Summit Landform position (three-dimensional): Tread Down-slope shape: Convex Across-slope shape: Convex Parent material: Loose sandy glaciofluvial deposits Typical profile H1 - 0 to 7 inches: coarse sand H2 - 7 to 17 inches: coarse sand H3 - 17 to 64 inches: coarse sand Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Excessively drained Runoff class: Negligible Capacity of the most limiting layer to transmit water (Ksat): Very high (20.00 to 99.90 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 3.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 7s Hydrologic Soil Group: A Hydric soil rating: No Minor Components Merrimac Percent of map unit: 6 percent Hydric soil rating: No Custom Soil Resource Report 13 27 Hinckley Percent of map unit: 6 percent Hydric soil rating: No Eastchop Percent of map unit: 4 percent Hydric soil rating: No Enfield Percent of map unit: 4 percent Hydric soil rating: No 252B—Carver coarse sand, 3 to 8 percent slopes Map Unit Setting National map unit symbol: 98qd Elevation: 0 to 1,000 feet Mean annual precipitation: 37 to 50 inches Mean annual air temperature: 45 to 55 degrees F Frost-free period: 120 to 240 days Farmland classification: Not prime farmland Map Unit Composition Carver and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Carver Setting Landform: Outwash plains Landform position (two-dimensional): Shoulder Landform position (three-dimensional): Riser Down-slope shape: Convex Across-slope shape: Convex Parent material: Sandy glaciofluvial deposits; loose sandy glaciofluvial deposits Typical profile H1 - 0 to 7 inches: coarse sand H2 - 7 to 17 inches: coarse sand H3 - 17 to 64 inches: coarse sand Properties and qualities Slope: 3 to 8 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Excessively drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): Very high (20.00 to 99.90 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Custom Soil Resource Report 14 28 Frequency of ponding: None Available water storage in profile: Low (about 3.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 7s Hydrologic Soil Group: A Hydric soil rating: No Minor Components Hinckley Percent of map unit: 6 percent Hydric soil rating: No Merrimac Percent of map unit: 6 percent Hydric soil rating: No Enfield Percent of map unit: 4 percent Hydric soil rating: No Eastchop Percent of map unit: 4 percent Hydric soil rating: No 252C—Carver coarse sand, 8 to 15 percent slopes Map Unit Setting National map unit symbol: 98qf Elevation: 0 to 1,000 feet Mean annual precipitation: 37 to 50 inches Mean annual air temperature: 45 to 55 degrees F Frost-free period: 120 to 240 days Farmland classification: Not prime farmland Map Unit Composition Carver and similar soils: 75 percent Minor components: 25 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Carver Setting Landform: Ice-contact slopes Landform position (two-dimensional): Backslope Landform position (three-dimensional): Riser Down-slope shape: Linear Across-slope shape: Convex Parent material: Sandy glaciofluvial deposits; loose sandy glaciofluvial deposits Custom Soil Resource Report 15 29 Typical profile H1 - 0 to 7 inches: coarse sand H2 - 7 to 17 inches: coarse sand H3 - 17 to 64 inches: coarse sand Properties and qualities Slope: 8 to 15 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Excessively drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): Very high (20.00 to 99.90 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 3.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 7s Hydrologic Soil Group: A Hydric soil rating: No Minor Components Merrimac Percent of map unit: 9 percent Hydric soil rating: No Hinckley Percent of map unit: 8 percent Hydric soil rating: No Eastchop Percent of map unit: 4 percent Hydric soil rating: No Plymouth Percent of map unit: 4 percent Hydric soil rating: No 484D—Plymouth-Barnstable complex, hilly, extremely bouldery Map Unit Setting National map unit symbol: 98s2 Elevation: 0 to 1,000 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 55 degrees F Frost-free period: 140 to 240 days Farmland classification: Not prime farmland Custom Soil Resource Report 16 30 Map Unit Composition Plymouth and similar soils: 55 percent Barnstable and similar soils: 20 percent Minor components: 25 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Plymouth Setting Landform: Moraines Landform position (two-dimensional): Backslope Landform position (three-dimensional): Side slope Down-slope shape: Linear Across-slope shape: Convex Parent material: Loose sandy glaciofluvial deposits and/or loose sandy ablation till; loose sandy glaciofluvial deposits and/or loose sandy ablation till Typical profile H1 - 0 to 3 inches: loamy coarse sand H2 - 3 to 29 inches: gravelly loamy coarse sand H3 - 29 to 64 inches: gravelly coarse sand Properties and qualities Slope: 15 to 25 percent Percent of area covered with surface fragments: 9.0 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Excessively drained Runoff class: Very high Capacity of the most limiting layer to transmit water (Ksat): High to very high (6.00 to 20.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 3.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 7s Hydrologic Soil Group: A Hydric soil rating: No Description of Barnstable Setting Landform: Moraines Landform position (two-dimensional): Backslope Landform position (three-dimensional): Side slope Down-slope shape: Linear Across-slope shape: Convex Parent material: Friable loamy ablation till over reworked sandy glaciofluvial deposits; loamy ablation till over reworked sandy outwash Typical profile H1 - 0 to 1 inches: sandy loam H2 - 1 to 23 inches: sandy loam H3 - 23 to 64 inches: coarse sand Custom Soil Resource Report 17 31 Properties and qualities Slope: 15 to 25 percent Percent of area covered with surface fragments: 9.0 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Very high Capacity of the most limiting layer to transmit water (Ksat): High (2.00 to 6.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 4.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 7s Hydrologic Soil Group: A Hydric soil rating: No Minor Components Nantucket Percent of map unit: 10 percent Hydric soil rating: No Carver Percent of map unit: 5 percent Hydric soil rating: No Hinckley Percent of map unit: 5 percent Hydric soil rating: No Merrimac Percent of map unit: 5 percent Hydric soil rating: No 602—Urban land Map Unit Setting National map unit symbol: 98s7 Frost-free period: 120 to 220 days Farmland classification: Not prime farmland Map Unit Composition Urban land: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Custom Soil Resource Report 18 32 Description of Urban Land Setting Parent material: Excavated and filled land Minor Components Udipsamments Percent of map unit: 15 percent Hydric soil rating: Unranked Custom Soil Resource Report 19 33 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 20 34 United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/? cid=nrcs142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf Custom Soil Resource Report 21 35 Natural Resource Services, Inc. P.O. Box 311 Harrisville, RI 02830 401-568-7390 FAX 401-568-7490 December 3, 2018 Amy L. Vonhone Town of Yarmouth Health Office 1146 Route 28 South Yarmouth, MA 02664 Dear Ms. Vonhone: Enclosed please find information regarding soil evaluation test holes performed at a site on Station Avenue (Plat 97, Lots 1, 2 and Portion of 3). The information provided includes Percolation Test Form 12 as well as Form 11 for Test Holes 1 through 6. A site sketch depicting the location of the test holes and approximate distances to bench marks has been included. Please do not hesitate to contact me regarding the work performed. Very truly yours, Edward J. Avizinis, PWS, CPSS Soil Evaluator Enclosures Cc: Paul Sylvia, Ayoub Engineering 36 St a t i o n A v e fence corner property corner SW1 TH4TH3 TH1 TH2 TH5 TH6 SW2 up up 24/79 up 24/79 1/2 monitoring well property corner Ø Ø Ø % @A @A @A @A @A %% @A @A @A% USGS, MassGIS ¯ Soil Evaluation Site SketchStation Ave Yarmouth, MA MassGIS 2013 ImagePerformed byEdward J. Avizinis, PWS, CPSS - 11/29/18Located using hand-held Trimble GeoXT (c) MassGIS Natural Resource Services, Inc.PO Box 311 p: (401) 568-7390180 Tinkham Lane f: (401) 568-7490Harrisville, RI 02830 FOR ILLUSTRATIVE PURPOSES ONLYNOT A SURVEY PLAN 0 100 20050Feet Legend @A Approximate Test Hole Locations Approximate Site Location (Town GIS) Approximate SW Locations@A 37 St a t i o n A v e +/- 116'+/- 116'+/- 153'+/- 142'+/- 186'+/- 83'+/- 52'+/- 110'+/- 113'+/- 152' +/- 35'+/- 43'fence corner property corner SW1 TH4TH3 TH1 TH2 TH5 TH6 SW2 up up 24/79 up 24/79 1/2 monitoring well property corner Ø Ø Ø % @A @A @A @A @A %% @A @A @A% USGS, MassGIS ¯ Soil Evaluation Site SketchStation Ave Yarmouth, MA MassGIS 2013 ImagePerformed byEdward J. Avizinis, PWS, CPSS - 11/29/18Located using hand-held Trimble GeoXT (c) MassGIS Natural Resource Services, Inc.PO Box 311 p: (401) 568-7390180 Tinkham Lane f: (401) 568-7490Harrisville, RI 02830 FOR ILLUSTRATIVE PURPOSES ONLYNOT A SURVEY PLAN 0 100 20050Feet Legend @A Approximate Test Hole Locations Approximate Site Location (Town GIS) Approximate SW Locations@A 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 EXISTING HYDROCAD CALCULATIONS 60 Ex Abutter Existing runoff to abutter Routing Diagram for HydrocadEX Prepared by {enter your company name here}, Printed 1/30/2019 HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Subcat Reach Pond Link 61 HydrocadEX Printed 1/30/2019Prepared by {enter your company name here} Page 2HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (sq-ft) CN Description (subcatchment-numbers) 601 98 Paved parking, HSG A (Ex Abutter) 18,340 45 Woods, Poor, HSG A (Ex Abutter) 62 Type III 24-hr 2-Year Rainfall=3.26"HydrocadEX Printed 1/30/2019Prepared by {enter your company name here} Page 3HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=18,941 sf 3.17% Impervious Runoff Depth>0.08"Subcatchment Ex Abutter: Existing runoff Tc=5.0 min CN=47 Runoff=0.00 cfs 129 cf 63 Type III 24-hr 2-Year Rainfall=3.26"HydrocadEX Printed 1/30/2019Prepared by {enter your company name here} Page 4HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment Ex Abutter: Existing runoff to abutter [49] Hint: Tc<2dt may require smaller dt Runoff = 0.00 cfs @ 14.66 hrs, Volume= 129 cf, Depth> 0.08" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.26" Area (sf) CN Description 18,340 45 Woods, Poor, HSG A 601 98 Paved parking, HSG A 18,941 47 Weighted Average 18,340 96.83% Pervious Area 601 3.17% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 64 Type III 24-hr 10-Year Rainfall=4.74"HydrocadEX Printed 1/30/2019Prepared by {enter your company name here} Page 5HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=18,941 sf 3.17% Impervious Runoff Depth>0.45"Subcatchment Ex Abutter: Existing runoff Tc=5.0 min CN=47 Runoff=0.09 cfs 707 cf 65 Type III 24-hr 10-Year Rainfall=4.74"HydrocadEX Printed 1/30/2019Prepared by {enter your company name here} Page 6HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment Ex Abutter: Existing runoff to abutter [49] Hint: Tc<2dt may require smaller dt Runoff = 0.09 cfs @ 12.27 hrs, Volume= 707 cf, Depth> 0.45" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.74" Area (sf) CN Description 18,340 45 Woods, Poor, HSG A 601 98 Paved parking, HSG A 18,941 47 Weighted Average 18,340 96.83% Pervious Area 601 3.17% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 66 Type III 24-hr 25-Year Rainfall=5.88"HydrocadEX Printed 1/30/2019Prepared by {enter your company name here} Page 7HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=18,941 sf 3.17% Impervious Runoff Depth>0.88"Subcatchment Ex Abutter: Existing runoff Tc=5.0 min CN=47 Runoff=0.31 cfs 1,390 cf 67 Type III 24-hr 25-Year Rainfall=5.88"HydrocadEX Printed 1/30/2019Prepared by {enter your company name here} Page 8HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment Ex Abutter: Existing runoff to abutter [49] Hint: Tc<2dt may require smaller dt Runoff = 0.31 cfs @ 12.11 hrs, Volume= 1,390 cf, Depth> 0.88" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.88" Area (sf) CN Description 18,340 45 Woods, Poor, HSG A 601 98 Paved parking, HSG A 18,941 47 Weighted Average 18,340 96.83% Pervious Area 601 3.17% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 68 Type III 24-hr 100-Year Rainfall=8.15"HydrocadEX Printed 1/30/2019Prepared by {enter your company name here} Page 9HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=18,941 sf 3.17% Impervious Runoff Depth>2.02"Subcatchment Ex Abutter: Existing runoff Tc=5.0 min CN=47 Runoff=0.92 cfs 3,191 cf 69 Type III 24-hr 100-Year Rainfall=8.15"HydrocadEX Printed 1/30/2019Prepared by {enter your company name here} Page 10HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment Ex Abutter: Existing runoff to abutter [49] Hint: Tc<2dt may require smaller dt Runoff = 0.92 cfs @ 12.09 hrs, Volume= 3,191 cf, Depth> 2.02" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=8.15" Area (sf) CN Description 18,340 45 Woods, Poor, HSG A 601 98 Paved parking, HSG A 18,941 47 Weighted Average 18,340 96.83% Pervious Area 601 3.17% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 70 PROPOSED HYDROCAD CALCULATIONS 71 Bio#1 Area to Bio#1 Bldg Building Roof Canopy Canopy Roof Pro Abutter Proposed runoff to abutter To CB1 Area to CB#1 To CB2 Area to CB#2 To CB3 Area to CB#3 To DI#1 Area to DI#1 16 (16) MC-4500 CHAMBERS#1 18 (18) MC-4500 CHAMBERS#2 Bio1 Bioretention Area #1 Bio2 Bioretention Area #2 Routing Diagram for HydrocadPRO2 Prepared by {enter your company name here}, Printed 7/25/2019 HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Subcat Reach Pond Link HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 2HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (sq-ft) CN Description (subcatchment-numbers) 12,738 39 >75% Grass cover, Good, HSG A (Bio#1, Pro Abutter, To CB1, To CB2, To CB3) 27,358 98 Paved parking, HSG A (To CB1, To CB2, To CB3, To DI#1) 7,248 98 Unconnected roofs, HSG A (Bldg, Canopy) Type III 24-hr 2-Year Rainfall=3.26"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 3HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=4,670 sf 0.00% Impervious Runoff Depth>0.00"Subcatchment Bio#1: Area to Bio#1 Tc=5.0 min CN=39 Runoff=0.00 cfs 0 cf Runoff Area=3,600 sf 100.00% Impervious Runoff Depth>3.03"Subcatchment Bldg: Building Roof Tc=5.0 min CN=98 Runoff=0.26 cfs 908 cf Runoff Area=3,648 sf 100.00% Impervious Runoff Depth>3.03"Subcatchment Canopy: Canopy Roof Tc=5.0 min CN=98 Runoff=0.27 cfs 920 cf Runoff Area=3,472 sf 0.00% Impervious Runoff Depth>0.00"Subcatchment Pro Abutter: Proposed runoff Tc=5.0 min CN=39 Runoff=0.00 cfs 0 cf Runoff Area=12,777 sf 81.18% Impervious Runoff Depth>1.97"Subcatchment To CB1: Area to CB#1 Tc=5.0 min CN=87 Runoff=0.68 cfs 2,094 cf Runoff Area=3,348 sf 53.43% Impervious Runoff Depth>0.91"Subcatchment To CB2: Area to CB#2 Tc=5.0 min CN=71 Runoff=0.08 cfs 255 cf Runoff Area=9,960 sf 93.64% Impervious Runoff Depth>2.60"Subcatchment To CB3: Area to CB#3 Tc=5.0 min CN=94 Runoff=0.67 cfs 2,159 cf Runoff Area=5,869 sf 100.00% Impervious Runoff Depth>3.03"Subcatchment To DI#1: Area to DI#1 Tc=5.0 min CN=98 Runoff=0.43 cfs 1,480 cf Peak Elev=49.13' Storage=511 cf Inflow=0.68 cfs 2,094 cfPond 16: (16) MC-4500 CHAMBERS#1 Outflow=0.15 cfs 2,093 cf Peak Elev=49.51' Storage=827 cf Inflow=0.94 cfs 3,078 cfPond 18: (18) MC-4500 CHAMBERS#2 Outflow=0.16 cfs 3,077 cf Peak Elev=55.24' Storage=306 cf Inflow=0.69 cfs 2,388 cfPond Bio1: Bioretention Area #1 Outflow=0.26 cfs 2,387 cf Peak Elev=54.11' Storage=22 cf Inflow=0.08 cfs 255 cfPond Bio2: Bioretention Area #2 Outflow=0.04 cfs 255 cf Type III 24-hr 2-Year Rainfall=3.26"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 4HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment Bio#1: Area to Bio#1 [49] Hint: Tc<2dt may require smaller dt [73] Warning: Peak may fall outside time span Runoff = 0.00 cfs @ 24.00 hrs, Volume= 0 cf, Depth> 0.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.26" Area (sf) CN Description 4,670 39 >75% Grass cover, Good, HSG A 4,670 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Bldg: Building Roof [49] Hint: Tc<2dt may require smaller dt Runoff = 0.26 cfs @ 12.07 hrs, Volume= 908 cf, Depth> 3.03" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.26" Area (sf) CN Description 3,600 98 Unconnected roofs, HSG A 3,600 100.00% Impervious Area 3,600 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Canopy: Canopy Roof [49] Hint: Tc<2dt may require smaller dt Runoff = 0.27 cfs @ 12.07 hrs, Volume= 920 cf, Depth> 3.03" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.26" Type III 24-hr 2-Year Rainfall=3.26"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 5HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Area (sf) CN Description 3,648 98 Unconnected roofs, HSG A 3,648 100.00% Impervious Area 3,648 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Pro Abutter: Proposed runoff to abutter [49] Hint: Tc<2dt may require smaller dt [73] Warning: Peak may fall outside time span Runoff = 0.00 cfs @ 24.00 hrs, Volume= 0 cf, Depth> 0.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.26" Area (sf) CN Description 3,472 39 >75% Grass cover, Good, HSG A 3,472 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To CB1: Area to CB#1 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.68 cfs @ 12.08 hrs, Volume= 2,094 cf, Depth> 1.97" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.26" Area (sf) CN Description 10,373 98 Paved parking, HSG A 2,404 39 >75% Grass cover, Good, HSG A 12,777 87 Weighted Average 2,404 18.82% Pervious Area 10,373 81.18% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type III 24-hr 2-Year Rainfall=3.26"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 6HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment To CB2: Area to CB#2 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.08 cfs @ 12.09 hrs, Volume= 255 cf, Depth> 0.91" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.26" Area (sf) CN Description 1,789 98 Paved parking, HSG A 1,559 39 >75% Grass cover, Good, HSG A 3,348 71 Weighted Average 1,559 46.57% Pervious Area 1,789 53.43% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To CB3: Area to CB#3 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.67 cfs @ 12.07 hrs, Volume= 2,159 cf, Depth> 2.60" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.26" Area (sf) CN Description 9,327 98 Paved parking, HSG A 633 39 >75% Grass cover, Good, HSG A 9,960 94 Weighted Average 633 6.36% Pervious Area 9,327 93.64% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To DI#1: Area to DI#1 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.43 cfs @ 12.07 hrs, Volume= 1,480 cf, Depth> 3.03" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.26" Type III 24-hr 2-Year Rainfall=3.26"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 7HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Area (sf) CN Description 5,869 98 Paved parking, HSG A 5,869 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond 16: (16) MC-4500 CHAMBERS#1 Inflow Area = 12,777 sf, 81.18% Impervious, Inflow Depth > 1.97" for 2-Year event Inflow = 0.68 cfs @ 12.08 hrs, Volume= 2,094 cf Outflow = 0.15 cfs @ 11.80 hrs, Volume= 2,093 cf, Atten= 78%, Lag= 0.0 min Discarded = 0.15 cfs @ 11.80 hrs, Volume= 2,093 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 49.13' @ 12.50 hrs Surf.Area= 763 sf Storage= 511 cf Plug-Flow detention time= 20.5 min calculated for 2,093 cf (100% of inflow) Center-of-Mass det. time= 20.2 min ( 837.0 - 816.7 ) Volume Invert Avail.Storage Storage Description #1A 47.92' 1,323 cf 19.42'W x 39.32'L x 6.75'H Field A 5,153 cf Overall - 1,847 cf Embedded = 3,306 cf x 40.0% Voids #2A 48.67' 1,847 cf ADS_StormTech MC-4500 +Cap x 16 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap 2 Rows of 8 Chambers Cap Storage= +35.7 cf x 2 x 2 rows = 142.8 cf 3,169 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 47.92'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.15 cfs @ 11.80 hrs HW=48.00' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.15 cfs) Summary for Pond 18: (18) MC-4500 CHAMBERS#2 Inflow Area = 13,608 sf, 95.35% Impervious, Inflow Depth > 2.71" for 2-Year event Inflow = 0.94 cfs @ 12.07 hrs, Volume= 3,078 cf Outflow = 0.16 cfs @ 11.70 hrs, Volume= 3,077 cf, Atten= 83%, Lag= 0.0 min Discarded = 0.16 cfs @ 11.70 hrs, Volume= 3,077 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 49.51' @ 12.53 hrs Surf.Area= 842 sf Storage= 827 cf Plug-Flow detention time= 29.8 min calculated for 3,071 cf (100% of inflow) Center-of-Mass det. time= 29.5 min ( 805.6 - 776.1 ) Type III 24-hr 2-Year Rainfall=3.26"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 8HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1A 47.92' 1,448 cf 19.42'W x 43.34'L x 6.75'H Field A 5,680 cf Overall - 2,060 cf Embedded = 3,621 cf x 40.0% Voids #2A 48.67' 2,060 cf ADS_StormTech MC-4500 +Cap x 18 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap 2 Rows of 9 Chambers Cap Storage= +35.7 cf x 2 x 2 rows = 142.8 cf 3,508 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 47.92'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.16 cfs @ 11.70 hrs HW=48.00' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.16 cfs) Summary for Pond Bio1: Bioretention Area #1 Inflow Area = 14,139 sf, 66.97% Impervious, Inflow Depth > 2.03" for 2-Year event Inflow = 0.69 cfs @ 12.07 hrs, Volume= 2,388 cf Outflow = 0.26 cfs @ 12.30 hrs, Volume= 2,387 cf, Atten= 62%, Lag= 13.5 min Discarded = 0.26 cfs @ 12.30 hrs, Volume= 2,387 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 55.24' @ 12.30 hrs Surf.Area= 1,372 sf Storage= 306 cf Plug-Flow detention time= 5.8 min calculated for 2,382 cf (100% of inflow) Center-of-Mass det. time= 5.7 min ( 760.5 - 754.9 ) Volume Invert Avail.Storage Storage Description #1 55.00' 3,806 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 55.00 1,216 0 0 56.00 1,877 1,547 1,547 57.00 2,642 2,260 3,806 Device Routing Invert Outlet Devices #1 Discarded 55.00'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.26 cfs @ 12.30 hrs HW=55.24' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.26 cfs) Type III 24-hr 2-Year Rainfall=3.26"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 9HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Summary for Pond Bio2: Bioretention Area #2 Inflow Area = 3,348 sf, 53.43% Impervious, Inflow Depth > 0.91" for 2-Year event Inflow = 0.08 cfs @ 12.09 hrs, Volume= 255 cf Outflow = 0.04 cfs @ 12.26 hrs, Volume= 255 cf, Atten= 46%, Lag= 10.2 min Discarded = 0.04 cfs @ 12.26 hrs, Volume= 255 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 54.11' @ 12.26 hrs Surf.Area= 216 sf Storage= 22 cf Plug-Flow detention time= 3.7 min calculated for 254 cf (100% of inflow) Center-of-Mass det. time= 3.3 min ( 872.7 - 869.4 ) Volume Invert Avail.Storage Storage Description #1 54.00' 1,301 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 54.00 191 0 0 55.00 424 308 308 56.00 737 581 888 56.50 916 413 1,301 Device Routing Invert Outlet Devices #1 Discarded 54.00'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.04 cfs @ 12.26 hrs HW=54.11' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.04 cfs) Type III 24-hr 10-Year Rainfall=4.74"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 10HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=4,670 sf 0.00% Impervious Runoff Depth>0.15"Subcatchment Bio#1: Area to Bio#1 Tc=5.0 min CN=39 Runoff=0.00 cfs 58 cf Runoff Area=3,600 sf 100.00% Impervious Runoff Depth>4.50"Subcatchment Bldg: Building Roof Tc=5.0 min CN=98 Runoff=0.39 cfs 1,350 cf Runoff Area=3,648 sf 100.00% Impervious Runoff Depth>4.50"Subcatchment Canopy: Canopy Roof Tc=5.0 min CN=98 Runoff=0.39 cfs 1,368 cf Runoff Area=3,472 sf 0.00% Impervious Runoff Depth>0.15"Subcatchment Pro Abutter: Proposed runoff Tc=5.0 min CN=39 Runoff=0.00 cfs 43 cf Runoff Area=12,777 sf 81.18% Impervious Runoff Depth>3.32"Subcatchment To CB1: Area to CB#1 Tc=5.0 min CN=87 Runoff=1.13 cfs 3,536 cf Runoff Area=3,348 sf 53.43% Impervious Runoff Depth>1.92"Subcatchment To CB2: Area to CB#2 Tc=5.0 min CN=71 Runoff=0.17 cfs 536 cf Runoff Area=9,960 sf 93.64% Impervious Runoff Depth>4.05"Subcatchment To CB3: Area to CB#3 Tc=5.0 min CN=94 Runoff=1.02 cfs 3,361 cf Runoff Area=5,869 sf 100.00% Impervious Runoff Depth>4.50"Subcatchment To DI#1: Area to DI#1 Tc=5.0 min CN=98 Runoff=0.63 cfs 2,202 cf Peak Elev=50.17' Storage=1,145 cf Inflow=1.13 cfs 3,536 cfPond 16: (16) MC-4500 CHAMBERS#1 Outflow=0.15 cfs 3,535 cf Peak Elev=50.57' Storage=1,523 cf Inflow=1.41 cfs 4,730 cfPond 18: (18) MC-4500 CHAMBERS#2 Outflow=0.16 cfs 4,728 cf Peak Elev=55.47' Storage=645 cf Inflow=1.01 cfs 3,610 cfPond Bio1: Bioretention Area #1 Outflow=0.29 cfs 3,609 cf Peak Elev=54.43' Storage=102 cf Inflow=0.17 cfs 536 cfPond Bio2: Bioretention Area #2 Outflow=0.06 cfs 536 cf Type III 24-hr 10-Year Rainfall=4.74"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 11HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment Bio#1: Area to Bio#1 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.00 cfs @ 13.71 hrs, Volume= 58 cf, Depth> 0.15" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.74" Area (sf) CN Description 4,670 39 >75% Grass cover, Good, HSG A 4,670 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Bldg: Building Roof [49] Hint: Tc<2dt may require smaller dt Runoff = 0.39 cfs @ 12.07 hrs, Volume= 1,350 cf, Depth> 4.50" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.74" Area (sf) CN Description 3,600 98 Unconnected roofs, HSG A 3,600 100.00% Impervious Area 3,600 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Canopy: Canopy Roof [49] Hint: Tc<2dt may require smaller dt Runoff = 0.39 cfs @ 12.07 hrs, Volume= 1,368 cf, Depth> 4.50" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.74" Area (sf) CN Description 3,648 98 Unconnected roofs, HSG A 3,648 100.00% Impervious Area 3,648 100.00% Unconnected Type III 24-hr 10-Year Rainfall=4.74"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 12HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Pro Abutter: Proposed runoff to abutter [49] Hint: Tc<2dt may require smaller dt Runoff = 0.00 cfs @ 13.71 hrs, Volume= 43 cf, Depth> 0.15" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.74" Area (sf) CN Description 3,472 39 >75% Grass cover, Good, HSG A 3,472 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To CB1: Area to CB#1 [49] Hint: Tc<2dt may require smaller dt Runoff = 1.13 cfs @ 12.07 hrs, Volume= 3,536 cf, Depth> 3.32" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.74" Area (sf) CN Description 10,373 98 Paved parking, HSG A 2,404 39 >75% Grass cover, Good, HSG A 12,777 87 Weighted Average 2,404 18.82% Pervious Area 10,373 81.18% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To CB2: Area to CB#2 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.17 cfs @ 12.08 hrs, Volume= 536 cf, Depth> 1.92" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.74" Type III 24-hr 10-Year Rainfall=4.74"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 13HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Area (sf) CN Description 1,789 98 Paved parking, HSG A 1,559 39 >75% Grass cover, Good, HSG A 3,348 71 Weighted Average 1,559 46.57% Pervious Area 1,789 53.43% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To CB3: Area to CB#3 [49] Hint: Tc<2dt may require smaller dt Runoff = 1.02 cfs @ 12.07 hrs, Volume= 3,361 cf, Depth> 4.05" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.74" Area (sf) CN Description 9,327 98 Paved parking, HSG A 633 39 >75% Grass cover, Good, HSG A 9,960 94 Weighted Average 633 6.36% Pervious Area 9,327 93.64% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To DI#1: Area to DI#1 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.63 cfs @ 12.07 hrs, Volume= 2,202 cf, Depth> 4.50" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.74" Area (sf) CN Description 5,869 98 Paved parking, HSG A 5,869 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type III 24-hr 10-Year Rainfall=4.74"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 14HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Summary for Pond 16: (16) MC-4500 CHAMBERS#1 Inflow Area = 12,777 sf, 81.18% Impervious, Inflow Depth > 3.32" for 10-Year event Inflow = 1.13 cfs @ 12.07 hrs, Volume= 3,536 cf Outflow = 0.15 cfs @ 11.65 hrs, Volume= 3,535 cf, Atten= 87%, Lag= 0.0 min Discarded = 0.15 cfs @ 11.65 hrs, Volume= 3,535 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 50.17' @ 12.63 hrs Surf.Area= 763 sf Storage= 1,145 cf Plug-Flow detention time= 54.6 min calculated for 3,527 cf (100% of inflow) Center-of-Mass det. time= 54.2 min ( 856.1 - 801.9 ) Volume Invert Avail.Storage Storage Description #1A 47.92' 1,323 cf 19.42'W x 39.32'L x 6.75'H Field A 5,153 cf Overall - 1,847 cf Embedded = 3,306 cf x 40.0% Voids #2A 48.67' 1,847 cf ADS_StormTech MC-4500 +Cap x 16 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap 2 Rows of 8 Chambers Cap Storage= +35.7 cf x 2 x 2 rows = 142.8 cf 3,169 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 47.92'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.15 cfs @ 11.65 hrs HW=47.99' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.15 cfs) Summary for Pond 18: (18) MC-4500 CHAMBERS#2 Inflow Area = 13,608 sf, 95.35% Impervious, Inflow Depth > 4.17" for 10-Year event Inflow = 1.41 cfs @ 12.07 hrs, Volume= 4,730 cf Outflow = 0.16 cfs @ 11.60 hrs, Volume= 4,728 cf, Atten= 89%, Lag= 0.0 min Discarded = 0.16 cfs @ 11.60 hrs, Volume= 4,728 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 50.57' @ 12.68 hrs Surf.Area= 842 sf Storage= 1,523 cf Plug-Flow detention time= 62.5 min calculated for 4,718 cf (100% of inflow) Center-of-Mass det. time= 62.1 min ( 828.3 - 766.2 ) Volume Invert Avail.Storage Storage Description #1A 47.92' 1,448 cf 19.42'W x 43.34'L x 6.75'H Field A 5,680 cf Overall - 2,060 cf Embedded = 3,621 cf x 40.0% Voids #2A 48.67' 2,060 cf ADS_StormTech MC-4500 +Cap x 18 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap 2 Rows of 9 Chambers Type III 24-hr 10-Year Rainfall=4.74"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 15HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Cap Storage= +35.7 cf x 2 x 2 rows = 142.8 cf 3,508 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 47.92'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.16 cfs @ 11.60 hrs HW=48.00' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.16 cfs) Summary for Pond Bio1: Bioretention Area #1 Inflow Area = 14,139 sf, 66.97% Impervious, Inflow Depth > 3.06" for 10-Year event Inflow = 1.01 cfs @ 12.07 hrs, Volume= 3,610 cf Outflow = 0.29 cfs @ 12.39 hrs, Volume= 3,609 cf, Atten= 71%, Lag= 19.3 min Discarded = 0.29 cfs @ 12.39 hrs, Volume= 3,609 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 55.47' @ 12.39 hrs Surf.Area= 1,527 sf Storage= 645 cf Plug-Flow detention time= 11.2 min calculated for 3,609 cf (100% of inflow) Center-of-Mass det. time= 11.0 min ( 763.2 - 752.2 ) Volume Invert Avail.Storage Storage Description #1 55.00' 3,806 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 55.00 1,216 0 0 56.00 1,877 1,547 1,547 57.00 2,642 2,260 3,806 Device Routing Invert Outlet Devices #1 Discarded 55.00'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.29 cfs @ 12.39 hrs HW=55.47' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.29 cfs) Summary for Pond Bio2: Bioretention Area #2 Inflow Area = 3,348 sf, 53.43% Impervious, Inflow Depth > 1.92" for 10-Year event Inflow = 0.17 cfs @ 12.08 hrs, Volume= 536 cf Outflow = 0.06 cfs @ 12.43 hrs, Volume= 536 cf, Atten= 67%, Lag= 20.6 min Discarded = 0.06 cfs @ 12.43 hrs, Volume= 536 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 54.43' @ 12.43 hrs Surf.Area= 290 sf Storage= 102 cf Plug-Flow detention time= 11.7 min calculated for 534 cf (100% of inflow) Center-of-Mass det. time= 11.3 min ( 857.8 - 846.5 ) Type III 24-hr 10-Year Rainfall=4.74"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 16HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 54.00' 1,301 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 54.00 191 0 0 55.00 424 308 308 56.00 737 581 888 56.50 916 413 1,301 Device Routing Invert Outlet Devices #1 Discarded 54.00'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.06 cfs @ 12.43 hrs HW=54.43' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.06 cfs) Type III 24-hr 25-Year Rainfall=5.88"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 17HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=4,670 sf 0.00% Impervious Runoff Depth>0.41"Subcatchment Bio#1: Area to Bio#1 Tc=5.0 min CN=39 Runoff=0.02 cfs 160 cf Runoff Area=3,600 sf 100.00% Impervious Runoff Depth>5.64"Subcatchment Bldg: Building Roof Tc=5.0 min CN=98 Runoff=0.48 cfs 1,692 cf Runoff Area=3,648 sf 100.00% Impervious Runoff Depth>5.64"Subcatchment Canopy: Canopy Roof Tc=5.0 min CN=98 Runoff=0.49 cfs 1,714 cf Runoff Area=3,472 sf 0.00% Impervious Runoff Depth>0.41"Subcatchment Pro Abutter: Proposed runoff Tc=5.0 min CN=39 Runoff=0.01 cfs 119 cf Runoff Area=12,777 sf 81.18% Impervious Runoff Depth>4.40"Subcatchment To CB1: Area to CB#1 Tc=5.0 min CN=87 Runoff=1.48 cfs 4,685 cf Runoff Area=3,348 sf 53.43% Impervious Runoff Depth>2.80"Subcatchment To CB2: Area to CB#2 Tc=5.0 min CN=71 Runoff=0.25 cfs 781 cf Runoff Area=9,960 sf 93.64% Impervious Runoff Depth>5.18"Subcatchment To CB3: Area to CB#3 Tc=5.0 min CN=94 Runoff=1.29 cfs 4,295 cf Runoff Area=5,869 sf 100.00% Impervious Runoff Depth>5.64"Subcatchment To DI#1: Area to DI#1 Tc=5.0 min CN=98 Runoff=0.78 cfs 2,758 cf Peak Elev=51.12' Storage=1,688 cf Inflow=1.48 cfs 4,685 cfPond 16: (16) MC-4500 CHAMBERS#1 Outflow=0.15 cfs 4,683 cf Peak Elev=51.51' Storage=2,111 cf Inflow=1.77 cfs 6,010 cfPond 18: (18) MC-4500 CHAMBERS#2 Outflow=0.16 cfs 6,008 cf Peak Elev=55.66' Storage=950 cf Inflow=1.26 cfs 4,610 cfPond Bio1: Bioretention Area #1 Outflow=0.32 cfs 4,609 cf Peak Elev=54.69' Storage=188 cf Inflow=0.25 cfs 781 cfPond Bio2: Bioretention Area #2 Outflow=0.07 cfs 781 cf Type III 24-hr 25-Year Rainfall=5.88"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 18HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment Bio#1: Area to Bio#1 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.02 cfs @ 12.34 hrs, Volume= 160 cf, Depth> 0.41" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.88" Area (sf) CN Description 4,670 39 >75% Grass cover, Good, HSG A 4,670 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Bldg: Building Roof [49] Hint: Tc<2dt may require smaller dt Runoff = 0.48 cfs @ 12.07 hrs, Volume= 1,692 cf, Depth> 5.64" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.88" Area (sf) CN Description 3,600 98 Unconnected roofs, HSG A 3,600 100.00% Impervious Area 3,600 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Canopy: Canopy Roof [49] Hint: Tc<2dt may require smaller dt Runoff = 0.49 cfs @ 12.07 hrs, Volume= 1,714 cf, Depth> 5.64" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.88" Area (sf) CN Description 3,648 98 Unconnected roofs, HSG A 3,648 100.00% Impervious Area 3,648 100.00% Unconnected Type III 24-hr 25-Year Rainfall=5.88"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 19HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Pro Abutter: Proposed runoff to abutter [49] Hint: Tc<2dt may require smaller dt Runoff = 0.01 cfs @ 12.34 hrs, Volume= 119 cf, Depth> 0.41" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.88" Area (sf) CN Description 3,472 39 >75% Grass cover, Good, HSG A 3,472 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To CB1: Area to CB#1 [49] Hint: Tc<2dt may require smaller dt Runoff = 1.48 cfs @ 12.07 hrs, Volume= 4,685 cf, Depth> 4.40" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.88" Area (sf) CN Description 10,373 98 Paved parking, HSG A 2,404 39 >75% Grass cover, Good, HSG A 12,777 87 Weighted Average 2,404 18.82% Pervious Area 10,373 81.18% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To CB2: Area to CB#2 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.25 cfs @ 12.08 hrs, Volume= 781 cf, Depth> 2.80" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.88" Type III 24-hr 25-Year Rainfall=5.88"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 20HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Area (sf) CN Description 1,789 98 Paved parking, HSG A 1,559 39 >75% Grass cover, Good, HSG A 3,348 71 Weighted Average 1,559 46.57% Pervious Area 1,789 53.43% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To CB3: Area to CB#3 [49] Hint: Tc<2dt may require smaller dt Runoff = 1.29 cfs @ 12.07 hrs, Volume= 4,295 cf, Depth> 5.18" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.88" Area (sf) CN Description 9,327 98 Paved parking, HSG A 633 39 >75% Grass cover, Good, HSG A 9,960 94 Weighted Average 633 6.36% Pervious Area 9,327 93.64% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To DI#1: Area to DI#1 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.78 cfs @ 12.07 hrs, Volume= 2,758 cf, Depth> 5.64" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.88" Area (sf) CN Description 5,869 98 Paved parking, HSG A 5,869 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type III 24-hr 25-Year Rainfall=5.88"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 21HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Summary for Pond 16: (16) MC-4500 CHAMBERS#1 Inflow Area = 12,777 sf, 81.18% Impervious, Inflow Depth > 4.40" for 25-Year event Inflow = 1.48 cfs @ 12.07 hrs, Volume= 4,685 cf Outflow = 0.15 cfs @ 11.60 hrs, Volume= 4,683 cf, Atten= 90%, Lag= 0.0 min Discarded = 0.15 cfs @ 11.60 hrs, Volume= 4,683 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 51.12' @ 12.88 hrs Surf.Area= 763 sf Storage= 1,688 cf Plug-Flow detention time= 86.9 min calculated for 4,683 cf (100% of inflow) Center-of-Mass det. time= 86.6 min ( 880.7 - 794.1 ) Volume Invert Avail.Storage Storage Description #1A 47.92' 1,323 cf 19.42'W x 39.32'L x 6.75'H Field A 5,153 cf Overall - 1,847 cf Embedded = 3,306 cf x 40.0% Voids #2A 48.67' 1,847 cf ADS_StormTech MC-4500 +Cap x 16 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap 2 Rows of 8 Chambers Cap Storage= +35.7 cf x 2 x 2 rows = 142.8 cf 3,169 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 47.92'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.15 cfs @ 11.60 hrs HW=48.00' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.15 cfs) Summary for Pond 18: (18) MC-4500 CHAMBERS#2 Inflow Area = 13,608 sf, 95.35% Impervious, Inflow Depth > 5.30" for 25-Year event Inflow = 1.77 cfs @ 12.07 hrs, Volume= 6,010 cf Outflow = 0.16 cfs @ 11.35 hrs, Volume= 6,008 cf, Atten= 91%, Lag= 0.0 min Discarded = 0.16 cfs @ 11.35 hrs, Volume= 6,008 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 51.51' @ 12.91 hrs Surf.Area= 842 sf Storage= 2,111 cf Plug-Flow detention time= 92.6 min calculated for 5,995 cf (100% of inflow) Center-of-Mass det. time= 92.2 min ( 853.2 - 761.1 ) Volume Invert Avail.Storage Storage Description #1A 47.92' 1,448 cf 19.42'W x 43.34'L x 6.75'H Field A 5,680 cf Overall - 2,060 cf Embedded = 3,621 cf x 40.0% Voids #2A 48.67' 2,060 cf ADS_StormTech MC-4500 +Cap x 18 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap 2 Rows of 9 Chambers Type III 24-hr 25-Year Rainfall=5.88"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 22HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Cap Storage= +35.7 cf x 2 x 2 rows = 142.8 cf 3,508 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 47.92'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.16 cfs @ 11.35 hrs HW=47.99' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.16 cfs) Summary for Pond Bio1: Bioretention Area #1 Inflow Area = 14,139 sf, 66.97% Impervious, Inflow Depth > 3.91" for 25-Year event Inflow = 1.26 cfs @ 12.07 hrs, Volume= 4,610 cf Outflow = 0.32 cfs @ 12.45 hrs, Volume= 4,609 cf, Atten= 75%, Lag= 22.5 min Discarded = 0.32 cfs @ 12.45 hrs, Volume= 4,609 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 55.66' @ 12.45 hrs Surf.Area= 1,654 sf Storage= 950 cf Plug-Flow detention time= 16.1 min calculated for 4,609 cf (100% of inflow) Center-of-Mass det. time= 15.9 min ( 767.7 - 751.8 ) Volume Invert Avail.Storage Storage Description #1 55.00' 3,806 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 55.00 1,216 0 0 56.00 1,877 1,547 1,547 57.00 2,642 2,260 3,806 Device Routing Invert Outlet Devices #1 Discarded 55.00'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.32 cfs @ 12.45 hrs HW=55.66' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.32 cfs) Summary for Pond Bio2: Bioretention Area #2 Inflow Area = 3,348 sf, 53.43% Impervious, Inflow Depth > 2.80" for 25-Year event Inflow = 0.25 cfs @ 12.08 hrs, Volume= 781 cf Outflow = 0.07 cfs @ 12.47 hrs, Volume= 781 cf, Atten= 73%, Lag= 23.2 min Discarded = 0.07 cfs @ 12.47 hrs, Volume= 781 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 54.69' @ 12.47 hrs Surf.Area= 352 sf Storage= 188 cf Plug-Flow detention time= 19.4 min calculated for 781 cf (100% of inflow) Center-of-Mass det. time= 19.1 min ( 854.5 - 835.5 ) Type III 24-hr 25-Year Rainfall=5.88"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 23HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 54.00' 1,301 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 54.00 191 0 0 55.00 424 308 308 56.00 737 581 888 56.50 916 413 1,301 Device Routing Invert Outlet Devices #1 Discarded 54.00'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.07 cfs @ 12.47 hrs HW=54.69' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.07 cfs) Type III 24-hr 100-Year Rainfall=8.15"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 24HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=4,670 sf 0.00% Impervious Runoff Depth>1.22"Subcatchment Bio#1: Area to Bio#1 Tc=5.0 min CN=39 Runoff=0.11 cfs 474 cf Runoff Area=3,600 sf 100.00% Impervious Runoff Depth>7.91"Subcatchment Bldg: Building Roof Tc=5.0 min CN=98 Runoff=0.67 cfs 2,372 cf Runoff Area=3,648 sf 100.00% Impervious Runoff Depth>7.91"Subcatchment Canopy: Canopy Roof Tc=5.0 min CN=98 Runoff=0.67 cfs 2,404 cf Runoff Area=3,472 sf 0.00% Impervious Runoff Depth>1.22"Subcatchment Pro Abutter: Proposed runoff Tc=5.0 min CN=39 Runoff=0.08 cfs 353 cf Runoff Area=12,777 sf 81.18% Impervious Runoff Depth>6.59"Subcatchment To CB1: Area to CB#1 Tc=5.0 min CN=87 Runoff=2.17 cfs 7,019 cf Runoff Area=3,348 sf 53.43% Impervious Runoff Depth>4.71"Subcatchment To CB2: Area to CB#2 Tc=5.0 min CN=71 Runoff=0.42 cfs 1,313 cf Runoff Area=9,960 sf 93.64% Impervious Runoff Depth>7.43"Subcatchment To CB3: Area to CB#3 Tc=5.0 min CN=94 Runoff=1.81 cfs 6,165 cf Runoff Area=5,869 sf 100.00% Impervious Runoff Depth>7.91"Subcatchment To DI#1: Area to DI#1 Tc=5.0 min CN=98 Runoff=1.09 cfs 3,867 cf Peak Elev=53.83' Storage=2,913 cf Inflow=2.17 cfs 7,019 cfPond 16: (16) MC-4500 CHAMBERS#1 Outflow=0.15 cfs 7,016 cf Peak Elev=54.42' Storage=3,425 cf Inflow=2.48 cfs 8,568 cfPond 18: (18) MC-4500 CHAMBERS#2 Outflow=0.16 cfs 8,565 cf Peak Elev=56.06' Storage=1,665 cf Inflow=1.84 cfs 6,713 cfPond Bio1: Bioretention Area #1 Outflow=0.37 cfs 6,711 cf Peak Elev=55.18' Storage=387 cf Inflow=0.42 cfs 1,313 cfPond Bio2: Bioretention Area #2 Outflow=0.09 cfs 1,313 cf Type III 24-hr 100-Year Rainfall=8.15"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 25HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment Bio#1: Area to Bio#1 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.11 cfs @ 12.11 hrs, Volume= 474 cf, Depth> 1.22" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=8.15" Area (sf) CN Description 4,670 39 >75% Grass cover, Good, HSG A 4,670 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Bldg: Building Roof [49] Hint: Tc<2dt may require smaller dt Runoff = 0.67 cfs @ 12.07 hrs, Volume= 2,372 cf, Depth> 7.91" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=8.15" Area (sf) CN Description 3,600 98 Unconnected roofs, HSG A 3,600 100.00% Impervious Area 3,600 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Canopy: Canopy Roof [49] Hint: Tc<2dt may require smaller dt Runoff = 0.67 cfs @ 12.07 hrs, Volume= 2,404 cf, Depth> 7.91" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=8.15" Area (sf) CN Description 3,648 98 Unconnected roofs, HSG A 3,648 100.00% Impervious Area 3,648 100.00% Unconnected Type III 24-hr 100-Year Rainfall=8.15"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 26HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment Pro Abutter: Proposed runoff to abutter [49] Hint: Tc<2dt may require smaller dt Runoff = 0.08 cfs @ 12.11 hrs, Volume= 353 cf, Depth> 1.22" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=8.15" Area (sf) CN Description 3,472 39 >75% Grass cover, Good, HSG A 3,472 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To CB1: Area to CB#1 [49] Hint: Tc<2dt may require smaller dt Runoff = 2.17 cfs @ 12.07 hrs, Volume= 7,019 cf, Depth> 6.59" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=8.15" Area (sf) CN Description 10,373 98 Paved parking, HSG A 2,404 39 >75% Grass cover, Good, HSG A 12,777 87 Weighted Average 2,404 18.82% Pervious Area 10,373 81.18% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To CB2: Area to CB#2 [49] Hint: Tc<2dt may require smaller dt Runoff = 0.42 cfs @ 12.08 hrs, Volume= 1,313 cf, Depth> 4.71" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=8.15" Type III 24-hr 100-Year Rainfall=8.15"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 27HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Area (sf) CN Description 1,789 98 Paved parking, HSG A 1,559 39 >75% Grass cover, Good, HSG A 3,348 71 Weighted Average 1,559 46.57% Pervious Area 1,789 53.43% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To CB3: Area to CB#3 [49] Hint: Tc<2dt may require smaller dt Runoff = 1.81 cfs @ 12.07 hrs, Volume= 6,165 cf, Depth> 7.43" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=8.15" Area (sf) CN Description 9,327 98 Paved parking, HSG A 633 39 >75% Grass cover, Good, HSG A 9,960 94 Weighted Average 633 6.36% Pervious Area 9,327 93.64% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment To DI#1: Area to DI#1 [49] Hint: Tc<2dt may require smaller dt Runoff = 1.09 cfs @ 12.07 hrs, Volume= 3,867 cf, Depth> 7.91" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=8.15" Area (sf) CN Description 5,869 98 Paved parking, HSG A 5,869 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Type III 24-hr 100-Year Rainfall=8.15"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 28HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Summary for Pond 16: (16) MC-4500 CHAMBERS#1 Inflow Area = 12,777 sf, 81.18% Impervious, Inflow Depth > 6.59" for 100-Year event Inflow = 2.17 cfs @ 12.07 hrs, Volume= 7,019 cf Outflow = 0.15 cfs @ 11.20 hrs, Volume= 7,016 cf, Atten= 93%, Lag= 0.0 min Discarded = 0.15 cfs @ 11.20 hrs, Volume= 7,016 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 53.83' @ 13.49 hrs Surf.Area= 763 sf Storage= 2,913 cf Plug-Flow detention time= 164.6 min calculated for 7,002 cf (100% of inflow) Center-of-Mass det. time= 164.0 min ( 947.1 - 783.1 ) Volume Invert Avail.Storage Storage Description #1A 47.92' 1,323 cf 19.42'W x 39.32'L x 6.75'H Field A 5,153 cf Overall - 1,847 cf Embedded = 3,306 cf x 40.0% Voids #2A 48.67' 1,847 cf ADS_StormTech MC-4500 +Cap x 16 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap 2 Rows of 8 Chambers Cap Storage= +35.7 cf x 2 x 2 rows = 142.8 cf 3,169 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 47.92'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.15 cfs @ 11.20 hrs HW=47.99' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.15 cfs) Summary for Pond 18: (18) MC-4500 CHAMBERS#2 Inflow Area = 13,608 sf, 95.35% Impervious, Inflow Depth > 7.56" for 100-Year event Inflow = 2.48 cfs @ 12.07 hrs, Volume= 8,568 cf Outflow = 0.16 cfs @ 10.85 hrs, Volume= 8,565 cf, Atten= 94%, Lag= 0.0 min Discarded = 0.16 cfs @ 10.85 hrs, Volume= 8,565 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 54.42' @ 13.49 hrs Surf.Area= 842 sf Storage= 3,425 cf Plug-Flow detention time= 164.1 min calculated for 8,565 cf (100% of inflow) Center-of-Mass det. time= 163.9 min ( 918.0 - 754.1 ) Volume Invert Avail.Storage Storage Description #1A 47.92' 1,448 cf 19.42'W x 43.34'L x 6.75'H Field A 5,680 cf Overall - 2,060 cf Embedded = 3,621 cf x 40.0% Voids #2A 48.67' 2,060 cf ADS_StormTech MC-4500 +Cap x 18 Inside #1 Effective Size= 90.4"W x 60.0"H => 26.46 sf x 4.03'L = 106.5 cf Overall Size= 100.0"W x 60.0"H x 4.33'L with 0.31' Overlap 2 Rows of 9 Chambers Type III 24-hr 100-Year Rainfall=8.15"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 29HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Cap Storage= +35.7 cf x 2 x 2 rows = 142.8 cf 3,508 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 47.92'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.16 cfs @ 10.85 hrs HW=47.99' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.16 cfs) Summary for Pond Bio1: Bioretention Area #1 Inflow Area = 14,139 sf, 66.97% Impervious, Inflow Depth > 5.70" for 100-Year event Inflow = 1.84 cfs @ 12.07 hrs, Volume= 6,713 cf Outflow = 0.37 cfs @ 12.51 hrs, Volume= 6,711 cf, Atten= 80%, Lag= 26.0 min Discarded = 0.37 cfs @ 12.51 hrs, Volume= 6,711 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 56.06' @ 12.51 hrs Surf.Area= 1,925 sf Storage= 1,665 cf Plug-Flow detention time= 27.3 min calculated for 6,697 cf (100% of inflow) Center-of-Mass det. time= 27.1 min ( 778.7 - 751.6 ) Volume Invert Avail.Storage Storage Description #1 55.00' 3,806 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 55.00 1,216 0 0 56.00 1,877 1,547 1,547 57.00 2,642 2,260 3,806 Device Routing Invert Outlet Devices #1 Discarded 55.00'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.37 cfs @ 12.51 hrs HW=56.06' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.37 cfs) Summary for Pond Bio2: Bioretention Area #2 Inflow Area = 3,348 sf, 53.43% Impervious, Inflow Depth > 4.71" for 100-Year event Inflow = 0.42 cfs @ 12.08 hrs, Volume= 1,313 cf Outflow = 0.09 cfs @ 12.50 hrs, Volume= 1,313 cf, Atten= 78%, Lag= 25.7 min Discarded = 0.09 cfs @ 12.50 hrs, Volume= 1,313 cf Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 55.18' @ 12.50 hrs Surf.Area= 479 sf Storage= 387 cf Plug-Flow detention time= 33.9 min calculated for 1,313 cf (100% of inflow) Center-of-Mass det. time= 33.6 min ( 854.1 - 820.5 ) Type III 24-hr 100-Year Rainfall=8.15"HydrocadPRO2 Printed 7/25/2019Prepared by {enter your company name here} Page 30HydroCAD® 10.00-19 s/n 01750 © 2016 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 54.00' 1,301 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 54.00 191 0 0 55.00 424 308 308 56.00 737 581 888 56.50 916 413 1,301 Device Routing Invert Outlet Devices #1 Discarded 54.00'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.09 cfs @ 12.50 hrs HW=55.18' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.09 cfs) OPERATION AND MAINTENANCE PLAN 102 STORMWATER OPERATION & MAINTENANCE PLAN Seasons Corner Market 473, 479 & 487 Station Ave., Yarmouth, Massachusetts Date: February 23, 2023 1. Parcel and Stormwater Management System Owner Owner: Colbea Enterprises LLC 695 George Washington Hwy -------------------------------------------------- Lincoln, RI 02865 signature date Contact: Michael Gazdacko, 401-943-0005x356 Tenant/Operator: Colbea Enterprises LLC 695 George Washington Hwy --------------------------------------------------- Lincoln, RI 02865 signature date Contact: Michael Gazdacko, 401-943-0005x356 2. Party Responsible for Operation and Maintenance See Owner and Operator information above. The property owner is ultimately responsible for the maintenance and operation of all on-site drainage structures as defined in this plan and as further detailed in the approved site plan and related stormwater drainage study. As part of the approval of this plan, the owner and operator agree to allow municipal officials to periodically access the facility and inspect the storm water components and condition of the property as it relates to determining compliance with this plan. 3. General Information The purpose of this document is to outline the operation and maintenance of the stormwater management system proposed as part of the site plan for the Retail Fueling Facility at 473, 479 & 487 Station Avenue, Yarmouth, Massachusetts. The stormwater management system consists of three new deep sump catch basins; one drain inlet, and two Oil/Grit Separators to collect runoff from the pavement of LUHPLL area and the drive-thru area behind the building and discharge to two Bioretention Areas. The building roof discharges to Bioretention Area #1, and the canopy roof discharges to a subsurface infiltration system. See attached plans for layout and details of the site stormwater systems. In order to preserve the integrity of the infiltration systems, no materials will be stored on the roof of the building or the canopy. The only equipment to be installed on the roof will be that related to the HVAC system for the building and communication equipment. Any spills at the site (gas station) will be cleaned up as immediately and as possible, action will be taken to prevent spills from reaching any inlets. All maintenance shall be done by qualified persons and any materials removed must be disposed of in accordance with the laws, regulations and rules of the Commonwealth of Massachusetts and the Town of Yarmouth. 4. Schedule for Implementation of Maintenance Tasks The roofs, building, canopy and carwash gutters, decking and downspouts will be inspected at least once per year for any debris, particularly such as leaves, and cleaned as necessary but at a minimum of once each late autumn after all the leaves of nearby trees have fallen. All scuppers, downspouts and drainage structures will be maintained in good condition so that no runoff is diverted to overflow elsewhere. The subsurface infiltration system inlets will be inspected at least twice a year. Removed any debris that might clog the system, and per the StormTech design manual cleaning is required when sediment is at a depth of about 25% pipe volume or 25% pipe diameter. The catch basins will be inspected at least four times a year and at the end of the foliage and snow removal seasons. Cleaning is required four times a year or when the depth of deposits is greater than or equal to one half the depth from the bottom of the invert of the lowest pipe in the sump. The bioretention area should be inspected at least monthly, and after storm events greater than, or equal to the 1-year, 24-hour Type III precipitation event, to ensure the system is functioning properly. Inspect soil and repair eroded areas monthly. Re-mulch void areas as needed. Remove litter and debris monthly. Treat diseased vegetation as needed. Remove and replace dead vegetation twice per year (spring and fall). Remove invasive species as needed to prevent these species from spreading into the bioretention area. Replace mulch every two years, in the early spring. Upon failure, excavate the bioretention area, scarify bottom and sides, replace filter fabric and soil, replant, and mulch. The soil medium is to be tested every two years to determine the cation exchange capacity. When it drops below 5 meq/100 grams, the soil medium is to be replaced. The infiltration system’s Isolator Rows will be inspected at least twice the first year per manufacturer recommendations and subsequent years based on the oil and sediment accumulation rate determined during the first-year observations. Cleaning is required when sediment depth reaches 3” in the Isolator row. This structure should also be inspected after any fuel spill (gas station) or major storm. Polluted water or sediments removed from the chambers should be disposed of in accordance with all applicable local, state and federal laws and regulations. Cleaning includes jetting the chamber row and removal of accumulated oil and grease and sediment using a vacuum truck or other ordinary catch basin cleaning device. The Oil/grit separators will be inspected at least every month and after every major storm. Cleaning is required twice a year and includes removal of accumulated oil and grease and sediment using a vacuum truck or other ordinary catch basin cleaning device. The trash enclosure area is to be inspected weekly, and to be maintained so that no unsecured containers are stored there that may leak onto the pavement. Any spills will be cleaned up immediately. The enclosures will be swept occasionally to keep them in a clean and orderly condition. Trash containers must be kept covered to keep stormwater from contacting the inside. At least once each week, the lot including access ways, parking areas, fences, walls and landscape will be inspected and any trash will be collected and properly disposed. At least twice each year, the pavement areas will be swept and all sediment will be collected and properly disposed. No vehicle maintenance will be conducted on the site. No vehicle washing will be conducted on site. Any spills, particularly at the dispensing and tank area of the gas station will be cleaned up immediately. All station employees will be trained on company spill response procedures notification procedures. At least once each week all dispensing equipment including hoses and nozzles will be inspected for any signs of leaks or excessive wear and replaced or repaired as appropriate. During winter conditions the catch basin inlets and discharge outlets are to be kept clear of snow and ice at all times. Snow plowed from the pavement areas is to be stored on the grass areas designated on the plans, and at no time is it to be deposited inside or in front of the Bioretention Areas. Any snow in excess of the volume able to be stored on site is to be removed from the site and disposed of appropriately. Deicing is to be kept to the minimum amount possible to maintain customer safety. See attached Maintenance Log Form that includes schedule for each above item. 5. Public Safety Features There are no public safety features associated with this stormwater management system. 6. Estimated Operation and Maintenance Budget This is a small stormwater system, and the annual O&M Budget reflects approximately forty hours of operator/manager labor plus sweeping costs and is estimated to cost approximately $5,000/year. 7. Operation and Maintenance Reports The owner/operator will be the responsible party for post construction stormwater system operation and maintenance. The owner/operator is required to maintain a record keeping log of all required and performed maintenance and submit any reports relevant to operation and maintenance of the stormwater system, and any fees as required by the Town of Yarmouth. Any changes to this plan or the responsible parties will be reported to the Town of Yarmouth DPW within thirty days of the change. Stormwater Operation and Maintenance Log Form Convenience Store / Gas Station - owned by Colbea Enterprises LLC 473, 479 & 487 Station Avenue, Yarmouth, MA The purpose of this Log Form is to document inspection and maintenance of the stormwater management system. See the the system Operation and Maintenance Plan and System Management Plan for system description. Weekly Inspect Trash Enclosure for unsecured containers, clean up any spills. Inspect all dispensing equipment including hoses and nozzles for excessive wear or signs of leaks, replace or repair as necessary Inspect & remove trash on the site Monthly Inspect bioretention areas; repair eroded soil, re-mulch void areas & remove litter Oil/Grit Separator to be inspected Quarterly Catch Basins to be inspected for depth of deposits & cleaned when greater than or equal to one half the depth from the bottom. Semi-annually and after any major storm or fuel spill event Sweep all paved areas to collect and dispose of sediment, especially in the Spring to remove winter sand. Remove & replace dead vegetation in the bioretention areas. Inspect subsurface infiltration system inlets and the Isolator Row and clean as needed Oil/Grit Separator to be cleaned and require removal of accumulated oil and grease and sediment using a vacuum truck. Annually Inspect Roof and clean all debris and leaves, clear all scuppers and downspouts for proper flow Bi-annually Replace mulch in the bioretention areas & test soil medium cation exchange capacity Date Initials Description of Activity Comments, Observations, Recommendations An company 106 2 THE MOST ADVANCED NAME IN WATER MANAGEMENT SOLUTIONS TM ECCENTRIC HEADER MANHOLE WITH OVERFLOW WEIR STORMTECH ISOLATOR ROW OPTIONAL PRE-TREATMENT OPTIONAL ACCESS STORMTECH CHAMBERS 107 108  )( 109