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HomeMy WebLinkAboutSP-22-006 - Supplemental - 1459 Shelburne Road (44) Stormwater Report Proposed Infant Care Facility 1459 Shelburne Road (Route 7) South Burlington, Vermont Submitted on behalf of: The Homestead School 1475 Shelburne Road (Route 7) South Burlington, Vermont Prepared by: Krebs and Lansing Consulting Engineers, Inc. Greg Dixson, P.E. VT#100256 164 Main Street, Suite 201 Colchester, Vermont 05446 (802) 878-0375 greg.dixson@krebsandlansing.com February 23, 2022 ___________ Homestead School – Proposed Infant Care Facility - 1459 Shelburne Road Stormwater Report Table of Contents 1.0 – Introduction Page 1 2.0 – Overview of Modeling Methodology & Source Information Page 2 3.0 – Description of Analysis Points Page 2 4.0 – Pre-Development Site Conditions Page 2 5.0 – Post-Development Site Conditions Page 3 6.0 – Summary Page 3 List of Appendices Appendix A – NRCS Soil Report Appendix B – State of Vermont Compliance Workbook Appendix C – Rainfall Frequency Data Appendix D - HydroCAD Reports ______________ Homestead School – Proposed Infant Care Facility - 1459 Shelburne Road Stormwater Report 1 Section 1.0 – Introduction The following plan outlines the stormwater and drainage standards for the Homestead Schools proposed Infant Care Facility at 1459 Shelburne Road, South Burlington. The project has designed a stormwater system to treat and temporarily contain stormwater runoff from the proposed site and a large portion of the 1475 Shelburne Road site. The stormwater runoff will be managed by a large Bioretention Swale/Basin with underdrain at the rear of the property. The best management practice (BMP) was designed/sized using State of Vermont Stormwater manual, workbooks, worksheets, calculations, and forms. The BMP will manage 1.05 acres, which is the majority of 1459 Shelburne Road property, the rear parking lot and the recently renovated playground on 1475 Shelburne Road. The calculations assumed all the recently renovated playground surface to be impervious. However, if portions of the playground need to be disturbed for the new project and interconnection of the properties, the Contractor will replace these portions with a pervious cross sections. This site could not take advantage of the infiltration because it is located on Hydrologic Group D soils, which are poor draining. Some infiltration is anticipated, but to be conservative, it is not included in our calculations. The BMP was sized to contain both the water quality storm (WQv) and channel protection storm (CPv) prior to outlet over the emergency spill way. Evaluation of both QP10 and QP100 would not be required because the site directly outlets to Lake Champlain (QP10 waiver) and has less than 10 acres of impervious (QP100 waiver). However, both larger storm events were evaluated from pre-development to post-development. Evaluations showed there is a large reduction in the 10-year storm and a slight reduction in the 100-year storm. Per South Burlington regulations, the 25-year storm was also evaluated and saw a slight reduction from pre-development to post-development. Stormwater treatment will be accomplished by the shallow sloped grass lined swales, sediment forebay, stone diaphragm at the edge of parking, and the stone of the bioretention basin/swale. Channel protection will be achieved using a small orifice attached to the end of the 4” underdrain outlet. Below are the peak flow values for both pre and post development. As mentioned above the Project evaluated the pre and post for the 1-year, 10-year, 25-year, and 100-year 24-hour storm events. For post development we also analyzed the water quality storm event. Peak Flow Comparison (cfs) Analysis Point 1-year 10-year 25-year 100-year Pre Post Pre Post Pre Post Pre Post SN001 1.43 0.05 2.38 0.42 3.24 2.30 3.57 3.34 *Post-development peak flow for WQv = 0.04 ______________ Homestead School – Proposed Infant Care Facility - 1459 Shelburne Road Stormwater Report 2 Section 2.0 – Overview of Modeling Methodology & Source Information The pre- and post-development Site conditions were modeled using the HydroCAD modeling program, version 10. This program was developed in accordance with the methodology published by the USDA Soil Conservation Service TR-55 document. Precipitation data used in the analysis, which was obtained from the NOAA Atlas 14 precipitation frequency estimates, is shown in the table below. Recurrence Interval 24-hour storm depth Water Quality 1.00 inches 1-year storm 1.88 inches 10-year storm 3.20 inches 25-year storm 3.82 inches 100-year storm 4.78 inches Section 3.0 – Description of Analysis Points The watershed model analyzed the discharge of runoff from the Site at one analysis points downstream of the proposed development. The selected analysis point is described below and can be found in the Plan Set on page C-1.01 Proposed Stormwater Plan. The analysis points and total area assessed for pre- and post- development remain the same, allowing direct comparison of the values. Analysis Point #1 Location: Latitude: N44° 25’ 53.8” Longitude: W73° 12’ 45.3” Pre-Development Drainage Area: 1.05 Acres Post-Development Drainage Area: 1.05 Acres Section 4.0 – Pre-Development Site Conditions The pre-development conditions and drainage patterns are shown on Sheet C-0.00 of the Plan Set. The area to be disturbed for the Project encompasses approximately 0.90 acres. The Site drains to unnamed tributaries and wetlands of Lake Champlain. The area is composed of an existing monument manufacturer, their business and production area. The site has multiple buildings with roadways and stone monuments skattered throughout. There are existing trees, vegetation, and grassed areas between buildings, roads, and material. The area included within 1475 Shelburne Road is an existing day care. The area draining to the practice is a recently renovated playground and parking lot. The recently renovated playground as described above was built with a material which does not infiltrate stormwater. The analyzed watershed is ______________ Homestead School – Proposed Infant Care Facility - 1459 Shelburne Road Stormwater Report 3 composed of D-soils. Overall, the existing watershed has approximately 0.45 acres of existing impervious of the total 1.05 acres. Section 5.0 – Post-Development Site Conditions The post-development conditions and drainage patterns are shown on sheet C-1.01 of the Plan Set. The proposed Project as described will result in an increase of 0.10 acres of impervious surface to the watershed, for a total of 0.55 acres of the 1.05 acre watershed. This is a combination of existing impervious which will remain, redeveloped impervious, new impervious, and existing impervious which will be revegetated.The total disturbed area associated with the Project installation will be approximately 0.90 acres. Section 6.0 – Summary The proposed permanent stormwater management systems have been designed to mitigate stormwater runoff impacts associated with the proposed project in accordance with State of Vermont Stormwater manual. This project will not disturb over an acre of impervious and will not be applying for a State of Vermont Construction Stormwater Discharge Permit. The project reduced the number of parking spaces to make room for additional capacity in the system. This also reduced the impervious surface outlined in our last submission. The project will continue to refine the design with Dave Wheeler and the South Burlington stormwater department, as needed. We will provide any further documentation and calculations needed.                                                                                                                     ___________  Homestead School – Proposed Infant Care Facility ‐ 1459 Shelburne Road  Stormwater Report               Appendix A  USDA NRCS Soils Report        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 forChittenden County, Vermont Homestead School NaturalResourcesConservationService February 3, 2022 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 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 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map................................................................................................................9 Legend................................................................................................................10 Map Unit Legend................................................................................................11 Map Unit Descriptions.........................................................................................11 Chittenden County, Vermont...........................................................................13 BlB—Belgrade and Eldridge soils, 3 to 8 percent slopes............................13 EwA—Enosburg and Whately soils, 0 to 3 percent slopes.........................14 EwB—Enosburg and Whately soils, 3 to 8 percent slopes.........................16 References............................................................................................................19 4 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 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 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 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 9 Custom Soil Resource ReportSoil Map 49213304921350492137049213904921410492143049214504921330492135049213704921390492141049214304921450642230 642250 642270 642290 642310 642330 642350 642370 642390 642410 642430 642250 642270 642290 642310 642330 642350 642370 642390 642410 642430 44° 25' 56'' N 73° 12' 46'' W44° 25' 56'' N73° 12' 37'' W44° 25' 52'' N 73° 12' 46'' W44° 25' 52'' N 73° 12' 37'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS8404590180270Feet0 10 20 40 60MetersMap Scale: 1:928 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) 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 1:15,800. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation ServiceWeb Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Chittenden County, VermontSurvey Area Data: Version 24, Sep 9, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jun 18, 2020—Jun 20, 2020 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 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI BlB Belgrade and Eldridge soils, 3 to 8 percent slopes 1.7 45.4% EwA Enosburg and Whately soils, 0 to 3 percent slopes 0.4 12.0% EwB Enosburg and Whately soils, 3 to 8 percent slopes 1.6 42.5% Totals for Area of Interest 3.6 100.0% Map Unit Descriptions 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. 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 Custom Soil Resource Report 11 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 Chittenden County, Vermont BlB—Belgrade and Eldridge soils, 3 to 8 percent slopes Map Unit Setting National map unit symbol: 9g32 Elevation: 90 to 1,000 feet Mean annual precipitation: 30 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 120 to 180 days Farmland classification: Farmland of statewide importance Map Unit Composition Belgrade and similar soils:46 percent Eldridge and similar soils:44 percent Minor components:10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Belgrade Setting Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Coarse-silty glaciolacustrine deposits Typical profile H1 - 0 to 7 inches: very fine sandy loam H2 - 7 to 23 inches: very fine sandy loam H3 - 23 to 60 inches: very fine sandy loam Properties and qualities Slope:3 to 8 percent Depth to restrictive feature:More than 80 inches Drainage class:Moderately well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately low to high (0.06 to 2.00 in/hr) Depth to water table:About 18 to 42 inches Frequency of flooding:None Frequency of ponding:None Available water supply, 0 to 60 inches: High (about 9.2 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2e Hydrologic Soil Group: B/D Ecological site: F142XB018VT - Moist Lake Plain Hydric soil rating: No Description of Eldridge Setting Landform:Terraces Landform position (three-dimensional):Tread Custom Soil Resource Report 13 Down-slope shape:Linear Across-slope shape:Linear Parent material:Sandy glaciolacustrine deposits over loamy glaciolacustrine deposits Typical profile H1 - 0 to 9 inches: loamy fine sand H2 - 9 to 27 inches: loamy fine sand H3 - 27 to 60 inches: silt loam Properties and qualities Slope:3 to 8 percent Depth to restrictive feature:More than 80 inches Drainage class:Moderately well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately low to moderately high (0.06 to 0.60 in/hr) Depth to water table:About 12 to 24 inches Frequency of flooding:None Frequency of ponding:None Available water supply, 0 to 60 inches: High (about 9.5 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2w Hydrologic Soil Group: C/D Ecological site: F142XB003VT - Moist Outwash Hydric soil rating: No Minor Components Raynham Percent of map unit:5 percent Landform:Depressions Hydric soil rating: Yes Enosburg Percent of map unit:5 percent Landform:Depressions Hydric soil rating: Yes EwA—Enosburg and Whately soils, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 9g3p Elevation: 90 to 1,000 feet Mean annual precipitation: 30 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 120 to 180 days Farmland classification: Farmland of statewide importance, if drained Custom Soil Resource Report 14 Map Unit Composition Enosburg and similar soils:44 percent Whately and similar soils:42 percent Minor components:14 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Enosburg Setting Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Sandy glaciofluvial deposits over loamy glaciolacustrine deposits Typical profile H1 - 0 to 8 inches: loamy sand H2 - 8 to 32 inches: coarse sand H3 - 32 to 65 inches: silt Properties and qualities Slope:0 to 3 percent Depth to restrictive feature:More than 80 inches Drainage class:Poorly drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat):Moderately low to moderately high (0.06 to 0.60 in/hr) Depth to water table:About 0 to 12 inches Frequency of flooding:None Frequency of ponding:None Available water supply, 0 to 60 inches: Moderate (about 7.5 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3w Hydrologic Soil Group: C/D Ecological site: F142XB004VT - Wet Outwash Depression Hydric soil rating: Yes Description of Whately Setting Landform:Depressions on terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Coarse-loamy glaciolacustrine deposits over clayey glaciolacustrine deposits Typical profile H1 - 0 to 8 inches: fine sandy loam H2 - 8 to 15 inches: fine sandy loam H3 - 15 to 65 inches: silty clay loam Properties and qualities Slope:0 to 3 percent Depth to restrictive feature:More than 80 inches Custom Soil Resource Report 15 Drainage class:Poorly drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Very low to moderately high (0.00 to 0.20 in/hr) Depth to water table:About 0 to 18 inches Frequency of flooding:None Frequency of ponding:None Available water supply, 0 to 60 inches: Moderate (about 8.9 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4w Hydrologic Soil Group: C/D Hydric soil rating: Yes Minor Components Swanton Percent of map unit:7 percent Landform:Knolls Hydric soil rating: Yes Raynham Percent of map unit:7 percent Landform:Knolls Hydric soil rating: Yes EwB—Enosburg and Whately soils, 3 to 8 percent slopes Map Unit Setting National map unit symbol: 9g3q Elevation: 90 to 1,000 feet Mean annual precipitation: 30 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 120 to 180 days Farmland classification: Farmland of statewide importance, if drained Map Unit Composition Enosburg and similar soils:44 percent Whately and similar soils:42 percent Minor components:14 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Enosburg Setting Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Concave, linear Custom Soil Resource Report 16 Parent material:Sandy glaciofluvial deposits over loamy glaciolacustrine deposits Typical profile H1 - 0 to 8 inches: loamy sand H2 - 8 to 32 inches: coarse sand H3 - 32 to 65 inches: silt Properties and qualities Slope:3 to 8 percent Depth to restrictive feature:More than 80 inches Drainage class:Poorly drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately low to moderately high (0.06 to 0.60 in/hr) Depth to water table:About 0 to 12 inches Frequency of flooding:None Frequency of ponding:None Available water supply, 0 to 60 inches: Moderate (about 7.5 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3w Hydrologic Soil Group: C/D Ecological site: F142XB004VT - Wet Outwash Depression Hydric soil rating: Yes Description of Whately Setting Landform:Depressions on terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear, concave Parent material:Coarse-loamy glaciolacustrine deposits over clayey glaciolacustrine deposits Typical profile H1 - 0 to 8 inches: fine sandy loam H2 - 8 to 15 inches: fine sandy loam H3 - 15 to 65 inches: silty clay loam Properties and qualities Slope:3 to 8 percent Depth to restrictive feature:More than 80 inches Drainage class:Poorly drained Runoff class: High Capacity of the most limiting layer to transmit water (Ksat):Very low to moderately high (0.00 to 0.20 in/hr) Depth to water table:About 0 to 18 inches Frequency of flooding:None Frequency of ponding:None Available water supply, 0 to 60 inches: Moderate (about 8.9 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4w Hydrologic Soil Group: C/D Hydric soil rating: Yes Custom Soil Resource Report 17 Minor Components Raynham Percent of map unit:7 percent Landform:Knolls Hydric soil rating: Yes Swanton Percent of map unit:7 percent Landform:Knolls Hydric soil rating: Yes Custom Soil Resource Report 18 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 19 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 20                                                                                                                     ___________  Homestead School – Proposed Infant Care Facility ‐ 1459 Shelburne Road  Stormwater Report               Appendix B  State of Vermont Compliance Workbook        Vermont Operational Stormwater Permit - Standards Compliance Workbook The name above will appear on all the discharge point tabs Site Summary Total SN1 SN2 SN3 SN4 SN5 SN6 SN7 SN8 SN9 New 0.20 0.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Redeveloped 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Existing 0.35 0.35 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Previously Authorized 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Total 0.55 0.55 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Site Area 1.05 1.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 44.43194 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 -73.21228 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Receiving Water Lake Champlain 0 Recharge Total SN1 SN2 SN3 SN4 SN5 SN6 SN7 SN8 SN9 Required 0.0275 0.0275 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Provided 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Standard met?No No n/a n/a n/a n/a n/a n/a n/a n/a Notes: Water Quality Total SN1 SN2 SN3 SN4 SN5 SN6 SN7 SN8 SN9 Required 0.0456 0.0456 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Provided 0.0467 0.0467 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Standard met?Yes Yes n/a n/a n/a n/a n/a n/a n/a n/a Notes: Channel ProtectionImperviousProject Name Do not fill this tab out, apart from the project name and notes. It will auto-populated based on the values on the discharge point tabs. Discharge points (SN) will only show on the summary if an area has been entered on that tab. Areas listed below are those seeking permit coverage. Homestead School Latitude Longitude A minimum WQ V of 0.2" (P*R V ) is required for sites with low impervious (<16.67%). This calculation has not been incorporated into this workbook. Designers should check that the minimum WQ V has been met for their site. Last Updated 8/28/2018 Summary: Page 3 of 13 Vermont Operational Stormwater Permit - Standards Compliance Workbook Total SN1 SN2 SN3 SN4 SN5 SN6 SN7 SN8 SN9 Standard Applies?Yes Yes 0 0 0 0 0 0 0 Waiver n/a n/a Method Extended Detention Hydrologic Condition Method n/a n/a n/a n/a n/a n/a n/a HCV 0.0593 0.0593 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 TV Provided 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Notes: Overbank Flood Protection SN1 SN2 SN3 SN4 SN5 SN6 SN7 SN8 SN9 Standard Applies?Yes Yes 0 0 0 0 0 0 0 Pre-Dev Q (cfs)2.38 0 Routed, Post-Dev Q (cfs)0.42 0 Waiver ≥10 sq mi n/a Notes: Extreme Flood Protection SN1 SN2 SN3 SN4 SN5 SN6 SN7 SN8 SN9 Standard Applies?No Yes Pre-Dev Q (cfs)0 0 Routed, Post-Dev Q (cfs)0 0 Waiver < 10 ac impervious n/a Notes: General Notes Last Updated 8/28/2018 Summary: Page 4 of 13 Vermont Operational Stormwater Permit - Standards Compliance Workbook Last Updated 8/28/2018 Summary: Page 5 of 13 Vermont Operational Stormwater Permit - Standards Compliance Workbook General Discharge Point Information Project name Discharge point serial number (e.g. S/N 001) Name of receiving water Latitude (decimal degrees to five decimal places) Longitude (decimal degrees to five decimal places) Precipitation Data NOAA Atlas 14 Storm WQ Storm 1 yr, 24 hr 10 yr, 24 hr 100 yr, 24 hr Precipitation (inches) 1.00 1.88 3.20 4.78 Drainage Area Information Landuse A B C D Total Grass 0.550 0.000 0.000 0.000 0.550 Meadow 0.000 0.000 0.000 0.000 0.000 Woods 0.030 0.000 0.000 0.000 0.030 Existing Impervious 0.470 0.000 0.000 0.000 0.470 Impervious previously authorized under 2002 VSMM (not included in calculations)0.000 Total Pre Site Area 1.050 % Landuse A B C D Total Grass 0.500 0.000 0.000 0.000 0.500 Meadow 0.000 0.000 0.000 0.000 0.000 Woods 0.000 0.000 0.000 0.000 0.000 New Impervious 0.200 0.000 0.000 0.000 0.200 19.0% Existing for Permit Coverage (Treated to New Standards) 0.350 0.000 0.000 0.000 0.350 33.3% Existing Impervious Not for Permit Coverage 0.000 0.0% Redeveloped Impervious 0.000 0.0% 0.000 Total Site Area 1.050 Total Impervious for Permit Coverage 0.550 Net Reduced Impervious 0.000 0.0% Reduced Existing Impervious (for redevelopment)0.120 100.0% Average Catchment Slope, Y (%) Hydraulic Length, l (ft) Pre Development 3.5 340.00 Post Development 4.5 315.00 Impervious previously authorized under 2002 VSMM Post Development Land Use (acres) Information for Calculating TC by the Watershed Lag Method Homestead School SN-001 Pre Development Land Use (acres) Lake Champlain 44.43194 -73.21228 * Preciptation values shall be obtained from Last Updated 8/28/2018 SN1: Page 6 of 13 Vermont Operational Stormwater Permit - Standards Compliance Workbook Runoff Calculations 1 yr, 24-hr 10 yr, 24-hr 100 yr, 24-hr 0.0648 0.1162 0.1852 0.0759 0.1360 0.2148 Tier 1/Runoff Reduction Practices Practice TV (ac-ft)TV (ac-ft) Runoff Reduction Calculations Standard Re WQ CP QP10 QP100 TV Required (ac-ft)0.0275 0.0456 0.0593 0.1063 0.1621 TV Provided (ac-ft)0.0000 0.0000 0.0000 0.0000 0.0000 TV Remaining (ac-ft)0.0275 0.0456 0.0593 0.1063 0.1621 Standard met with HCM?No No No No No Post-Development CN n/a 94 88 82 77 CNadj n/a 94 88 82 77 Pre-Development CN n/a n/a 86 79 73 Groundwater Recharge Standard (Re)2 Standard Applicable? ReV 0.0275 Standard met with Tier 1 Practices? No Recharge Notes: Reason recharge not required (if No is selected):HSG D Soils Standard not applicable. List all Tier 1 practices below with the associated treatment volume (T V ). The T V will be applied to all treatment standards, except for Green Roofs, which do not receive recharge or water quality credit. Please include the appropriate STP worksheet(s) with the application. Predevelopment runoff volume (ac-ft) Pre-routed, post development runoff volume (ac-ft) Practice Yes No Last Updated 8/28/2018 SN1: Page 7 of 13 Vermont Operational Stormwater Permit - Standards Compliance Workbook Water Quality Treatment Standard (WQ)1 1 (ac-ft)Apply Reduction? WQV - New & Existing 0.0456 0.0% WQV - Redevelopment 0.0000 100.0%Max 25% applied Total WQV 0.0456 WQV met with Tier 1 practices 0.0000 1 WQV to be met with Tier 2 and/or Tier 3 practices 0.0456 WQV Provided (ac-ft)Tier 0.0467 Tier 2 Total WQV Provided (ac-ft)0.0467 ac-ft Is the WQV Standard met?Yes Water Quality Notes: Channel Protection Standard (CP)1 1 Standard Applicable? Standard Met with HCM?No Provide Extended Detention for:0.076 ac-ft Warm or Cold Water Fishery?→Provide: FALSE Extended Detention STP: CNAdj 88 4.5 (Watershed Lag Method) Channel Protection Notes: Modeling Info: When demonstrating CP compliance with extended detention in a hydrologic model, use the CN and T C below if the practice being modelled is not a Tier 1 practice. The CN Adj takes into account the reduction in runoff volume achieved through Tier 1 practices. The T C is calculated by the watershed lag method using CN Adj as CN'. OR The Alternative Extended Detention Method (§2.2.5.4) is being used. 12 hours of extended detention The channel protection standard has not been fully met. Either increase Tv credit to fully meet HCM or provide extended detention. Is all impervious treated by disconnection? % Net Reduction % Removed Existing Impervious (Redevelopment) See the Vermont Water Quality Standards for warm and cold water designations Dry Swale provides 8.8 hours extended detention. Used Smallest oriface. Post Development TC (min) Bioretention (not designed to infiltrate) Tier 2 & 3 Water Quality PracticeNOTE: Please include a copy of the appropriate STP worksheet(s) with the application. [volume of forbay = 195 c.f. (10% WQv)]+[volume in stone = 1,600 c.f.(85%) ]+ [volume ED = + 240 c.f. (less than 50%)] = 2,035 c.f. = 0.0467 acre-ft (more than 50% in stone & forebay) Bioretention Swale/Basin (not designed to infiltrate) Yes No Cold Warm No Yes (WQv met) No Yes No Yes Last Updated 8/28/2018 SN1: Page 8 of 13 Vermont Operational Stormwater Permit - Standards Compliance Workbook Overbank Flood Protection (QP10)1 Standard Applicable? Standard Met with HCM?No STP used: Pre-development peak discharge rate (cfs)2.38 Pre-routed, post-development peak discharge rate (cfs)2.94 Routed, post-development peak discharge rate (cfs)0.42 Pre-Development CN (Flow- weighted composite)79 7.4 CNAdj 82 5.5 Overbank Flood Notes: Extreme Flood Protection (QP100)2 Standard Applicable? Standard Met with HCM?No STP used: Pre-development peak discharge rate (cfs) Pre-routed, post-development peak discharge rate (cfs) Routed, post-development peak discharge rate (cfs) Pre-Development CN (Flow- weighted composite)73 8.8 CNAdj 77 6.5 Extreme Flood Notes: (Watershed Lag Method) The QP10 standard has not been fully met. Provide additional STPs to ensure post development peak runoff does not exceed pre development peak runoff for the 10 yr, 24 hour storm event. Dry Swale/Basin with Underdrain (not designed to infiltrate) The extreme standard has not been fully met. Provide additional STPs to ensure post development peak runoff does not exceed pre development peak runoff for the 100 yr, 24 hour storm event. Routed Post Development Discharge is less than Pre-Development Discharge Modeling Info: When demonstrating Q P10 compliance in a hydrologic model, use the following CN and T C below, if the practice used to meet Q P10 is not itself a Tier 1 practice. The CN Adj takes into account the reduction in runoff volume achieved through Tier 1 practices. The T C is calculated by the watershed lag method using CN Adj as CN'. <10 acres impervious Not required but the routed Post Development Discharge is less than Pre- Development Discharge. Pre-development = 3.57 cfs and Routed Post-development = 3.34 cfs. Direct discharge to drainage area ≥10 sq.mi Post Development TC (min) Post Development TC (min) Pre Development TC (min)(Watershed Lag Method) Pre Development TC (min) Modeling Info: When demonstrating Q P100 compliance in a hydrologic model, use the following CN and T C below, if the practice used to meet Q P100 is not a Tier 1 practice. The CN Adj takes into account the reduction in runoff volume achieved through runoff reduction practices. The T C is calculated by the watershed lag method using CN Adj as CN'. Waiver (if No is selected): Yes No Yes No Last Updated 8/28/2018 SN1: Page 9 of 13                                                                                                                     ___________  Homestead School – Proposed Infant Care Facility ‐ 1459 Shelburne Road  Stormwater Report               Appendix C  Rainfall Frequency Data        1/27/22, 11:34 AM Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=44.4319&lon=-73.2123&data=depth&units=english&series=pds 1/4 NOAA Atlas 14, Volume 10, Version 3 Location name: South Burlington, Vermont, USA* Latitude: 44.4319°, Longitude: -73.2123° Elevation: 150.42 ft*** source: ESRI Maps ** source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Perica, Sandra Pavlovic, Michael St. Laurent, Carl Trypaluk, Dale Unruh, Orlan Wilhite NOAA, National Weather Service, Silver Spring, Maryland PF_tabular | PF_graphical | Maps_&_aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Duration Average recurrence interval (years) 1 2 5 10 25 50 100 200 500 1000 5-min 0.299(0.245‑0.364)0.355(0.291‑0.433)0.447(0.365‑0.546)0.523(0.424‑0.642)0.628(0.487‑0.793)0.709(0.536‑0.907)0.790(0.572‑1.03)0.874(0.600‑1.17)0.987(0.647‑1.36)1.07(0.683‑1.50) 10-min 0.424(0.347‑0.516)0.503(0.412‑0.613)0.633(0.517‑0.773)0.741(0.601‑0.909)0.890(0.690‑1.12)1.00(0.758‑1.29)1.12(0.811‑1.47)1.24(0.851‑1.66)1.40(0.917‑1.93)1.52(0.968‑2.13) 15-min 0.498(0.409‑0.607)0.592(0.485‑0.721)0.745(0.608‑0.910)0.872(0.706‑1.07)1.05(0.812‑1.32)1.18(0.892‑1.51)1.32(0.954‑1.73)1.46(1.00‑1.95)1.65(1.08‑2.26)1.79(1.14‑2.50) 30-min 0.687(0.564‑0.837)0.817(0.669‑0.995)1.03(0.839‑1.26)1.21(0.977‑1.48)1.45(1.12‑1.83)1.63(1.23‑2.09)1.82(1.32‑2.38)2.01(1.38‑2.70)2.27(1.49‑3.13)2.47(1.57‑3.46) 60-min 0.876(0.719‑1.07)1.04(0.854‑1.27)1.31(1.07‑1.60)1.54(1.25‑1.89)1.85(1.43‑2.33)2.08(1.57‑2.67)2.32(1.68‑3.04)2.57(1.77‑3.45)2.90(1.90‑3.99)3.16(2.01‑4.42) 2-hr 1.10(0.906‑1.33)1.29(1.06‑1.56)1.60(1.32‑1.94)1.86(1.52‑2.27)2.22(1.73‑2.78)2.49(1.89‑3.17)2.77(2.02‑3.61)3.06(2.11‑4.07)3.45(2.28‑4.72)3.76(2.41‑5.22) 3-hr 1.23(1.02‑1.48)1.44(1.19‑1.73)1.77(1.46‑2.14)2.05(1.68‑2.49)2.44(1.92‑3.05)2.73(2.09‑3.47)3.04(2.23‑3.95)3.36(2.33‑4.45)3.80(2.51‑5.16)4.14(2.66‑5.73) 6-hr 1.44(1.20‑1.73)1.68(1.40‑2.01)2.07(1.72‑2.49)2.40(1.98‑2.89)2.85(2.25‑3.54)3.19(2.46‑4.03)3.54(2.63‑4.59)3.93(2.74‑5.18)4.47(2.98‑6.05)4.91(3.18‑6.74) 12-hr 1.64(1.38‑1.95)1.93(1.62‑2.29)2.39(2.00‑2.86)2.78(2.31‑3.33)3.31(2.64‑4.10)3.71(2.89‑4.67)4.14(3.10‑5.34)4.61(3.24‑6.04)5.30(3.55‑7.11)5.86(3.82‑7.99) 24-hr 1.88(1.59‑2.22)2.21(1.87‑2.61)2.75(2.31‑3.26)3.20(2.67‑3.81)3.82(3.07‑4.70)4.29(3.36‑5.36)4.78(3.61‑6.14)5.34(3.78‑6.94)6.16(4.15‑8.21)6.83(4.48‑9.24) 2-day 2.20(1.88‑2.58)2.58(2.19‑3.02)3.19(2.70‑3.75)3.69(3.10‑4.36)4.39(3.54‑5.35)4.91(3.87‑6.08)5.46(4.14‑6.95)6.08(4.33‑7.84)6.97(4.74‑9.22)7.70(5.08‑10.3) 3-day 2.45(2.09‑2.86)2.85(2.43‑3.33)3.49(2.97‑4.10)4.03(3.40‑4.74)4.77(3.87‑5.79)5.33(4.21‑6.57)5.92(4.50‑7.49)6.57(4.70‑8.44)7.50(5.12‑9.88)8.26(5.47‑11.0) 4-day 2.65(2.27‑3.09)3.07(2.63‑3.58)3.75(3.20‑4.38)4.31(3.65‑5.06)5.09(4.14‑6.16)5.68(4.50‑6.97)6.29(4.79‑7.93)6.97(5.00‑8.92)7.94(5.43‑10.4)8.72(5.79‑11.6) 7-day 3.18(2.74‑3.68)3.64(3.13‑4.22)4.40(3.77‑5.11)5.03(4.28‑5.87)5.89(4.82‑7.08)6.55(5.21‑7.99)7.23(5.53‑9.05)7.98(5.75‑10.1)9.02(6.21‑11.8)9.87(6.59‑13.1) 10-day 3.68(3.18‑4.25)4.19(3.62‑4.84)5.02(4.31‑5.81)5.70(4.87‑6.63)6.65(5.45‑7.95)7.37(5.88‑8.94)8.11(6.22‑10.1)8.91(6.45‑11.3)10.0(6.92‑13.0)10.9(7.31‑14.4) 20-day 5.24(4.56‑6.01)5.87(5.10‑6.74)6.90(5.98‑7.94)7.76(6.67‑8.96)8.94(7.37‑10.6)9.85(7.90‑11.8)10.8(8.29‑13.2)11.7(8.54‑14.7)13.0(9.05‑16.8)14.0(9.45‑18.3) 30-day 6.56(5.74‑7.50)7.30(6.37‑8.34)8.49(7.38‑9.73)9.49(8.19‑10.9)10.9(8.99‑12.8)11.9(9.59‑14.2)13.0(10.0‑15.8)14.0(10.3‑17.6)15.5(10.8‑19.9)16.5(11.2‑21.6) 45-day 8.23(7.22‑9.36)9.09(7.96‑10.3)10.5(9.15‑12.0)11.6(10.1‑13.3)13.2(11.0‑15.5)14.5(11.7‑17.2)15.7(12.1‑19.1)16.9(12.4‑21.1)18.5(13.0‑23.6)19.7(13.4‑25.6) 60-day 9.64(8.48‑10.9)10.6(9.31‑12.0)12.2(10.6‑13.8)13.4(11.7‑15.3)15.2(12.7‑17.8)16.6(13.5‑19.7)18.0(13.9‑21.7)19.3(14.3‑24.0)21.0(14.8‑26.8)22.3(15.2‑28.9) 1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates(for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper boundsare not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Top PF graphical 1/27/22, 11:34 AM Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=44.4319&lon=-73.2123&data=depth&units=english&series=pds 2/4 Back to Top Maps & aerials Small scale terrain 1/27/22, 11:34 AM Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=44.4319&lon=-73.2123&data=depth&units=english&series=pds 3/4 Large scale terrain Large scale map Large scale aerial + – 3km 2mi + – 100km 60mi + – 100km 60mi 1/27/22, 11:34 AM Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=44.4319&lon=-73.2123&data=depth&units=english&series=pds 4/4 Back to Top US Department of Commerce National Oceanic and Atmospheric Administration National Weather Service National Water Center 1325 East West Highway Silver Spring, MD 20910 Questions?: HDSC.Questions@noaa.gov Disclaimer + – 100km 60mi                                                                                                                     ___________  Homestead School – Proposed Infant Care Facility ‐ 1459 Shelburne Road  Stormwater Report               Appendix D  HydroCAD Reports        WQv 26S SN001 27P Forebay 44P Bioretension Swale/Basin Routing Diagram for Homestead Prepared by Krebs & Lansing Consulting Engineers, Inc., Printed 2/23/2022 HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type II 24-hr WQv Rainfall=1.00"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 2HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Summary for Subcatchment 26S: SN001 Runoff = 1.03 cfs @ 11.94 hrs, Volume= 0.044 af, Depth= 0.50" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Type II 24-hr WQv Rainfall=1.00" Area (ac) CN Description * 1.050 94 CN Modified 1.050 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.5 315 0.0450 1.50 Lag/CN Method, Lag Method Summary for Pond 27P: Forebay Inflow Area = 1.050 ac, 0.00% Impervious, Inflow Depth = 0.50" for WQv event Inflow = 1.03 cfs @ 11.94 hrs, Volume= 0.044 af Outflow = 1.03 cfs @ 11.95 hrs, Volume= 0.044 af, Atten= 0%, Lag= 0.3 min Primary = 1.03 cfs @ 11.95 hrs, Volume= 0.044 af Routing by Stor-Ind method, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Starting Elev= 151.00' Surf.Area= 200 sf Storage= 195 cf Peak Elev= 151.12' @ 11.95 hrs Surf.Area= 217 sf Storage= 221 cf (26 cf above start) Plug-Flow detention time= 70.3 min calculated for 0.040 af (90% of inflow) Center-of-Mass det. time= 0.7 min ( 828.0 - 827.3 ) Volume Invert Avail.Storage Storage Description #1 149.00'313 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 149.00 20 0 0 150.00 85 53 53 151.00 200 143 195 151.50 270 118 313 Device Routing Invert Outlet Devices #1 Primary 151.00'10.0' long x 4.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.38 2.54 2.69 2.68 2.67 2.67 2.65 2.66 2.66 2.68 2.72 2.73 2.76 2.79 2.88 3.07 3.32 Primary OutFlow Max=1.03 cfs @ 11.95 hrs HW=151.12' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 1.03 cfs @ 0.84 fps) Type II 24-hr WQv Rainfall=1.00"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 3HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Summary for Pond 44P: Bioretension Swale/Basin Inflow Area = 1.050 ac, 0.00% Impervious, Inflow Depth = 0.50" for WQv event Inflow = 1.03 cfs @ 11.95 hrs, Volume= 0.044 af Outflow = 0.04 cfs @ 13.37 hrs, Volume= 0.044 af, Atten= 96%, Lag= 85.3 min Primary = 0.04 cfs @ 13.37 hrs, Volume= 0.044 af Routing by Stor-Ind method, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Starting Elev= 147.50' Surf.Area= 2,000 sf Storage= 800 cf Peak Elev= 150.13' @ 13.37 hrs Surf.Area= 5,199 sf Storage= 1,837 cf (1,037 cf above start) Plug-Flow detention time= 765.2 min calculated for 0.026 af (58% of inflow) Center-of-Mass det. time= 392.3 min ( 1,220.3 - 828.0 ) Volume Invert Avail.Storage Storage Description #1 146.50' 1,600 cf Stone (Prismatic) Listed below (Recalc) 4,000 cf Overall x 40.0% Voids #2 148.50'51 cf Wetland Planting Soil (Prismatic) Listed below (Recalc) 2,550 cf Overall x 2.0% Voids #3 150.00' 2,868 cf Pond (Prismatic) Listed below (Recalc) 4,519 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 146.50 2,000 0 0 147.50 2,000 2,000 2,000 148.50 2,000 2,000 4,000 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 148.50 1,700 0 0 150.00 1,700 2,550 2,550 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 150.00 1,415 0 0 151.00 2,075 1,745 1,745 151.50 2,415 1,123 2,868 Device Routing Invert Outlet Devices #1 Primary 147.50'4.0" Round Culvert L= 30.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 147.50' / 147.10' S= 0.0133 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.09 sf #2 Device 1 147.50'1.0" Vert. Orifice/Grate C= 0.600 #3 Primary 151.00'10.0' long x 5.5' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.35 2.51 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.69 2.73 2.77 2.86 Type II 24-hr WQv Rainfall=1.00"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 4HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Primary OutFlow Max=0.04 cfs @ 13.37 hrs HW=150.13' (Free Discharge) 1=Culvert (Passes 0.04 cfs of 0.47 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.04 cfs @ 7.74 fps) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) CPv Pre Development CPv 83S SN001 99S Pre Dev Site SN001 113P Forebay 114P Bioretension Swale/Basin Routing Diagram for Homestead Prepared by Krebs & Lansing Consulting Engineers, Inc., Printed 2/23/2022 HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type II 24-hr 1 year Rainfall=1.88"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 2HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Summary for Subcatchment 83S: SN001 Runoff = 1.73 cfs @ 11.96 hrs, Volume= 0.076 af, Depth= 0.87" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Type II 24-hr 1 year Rainfall=1.88" Area (ac) CN Description * 1.050 88 CN Modified 1.050 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.5 Direct Entry, From SW Workbook Summary for Subcatchment 99S: Pre Dev Site SN001 Runoff = 1.43 cfs @ 11.98 hrs, Volume= 0.066 af, Depth= 0.76" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Type II 24-hr 1 year Rainfall=1.88" Area (ac) CN Description * 1.050 86 Workbook 1.050 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.9 340 0.0350 0.97 Lag/CN Method, Summary for Pond 113P: Forebay Inflow Area = 1.050 ac, 0.00% Impervious, Inflow Depth = 0.87" for 1 year event Inflow = 1.73 cfs @ 11.96 hrs, Volume= 0.076 af Outflow = 1.73 cfs @ 11.96 hrs, Volume= 0.076 af, Atten= 0%, Lag= 0.3 min Primary = 1.73 cfs @ 11.96 hrs, Volume= 0.076 af Routing by Stor-Ind method, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Starting Elev= 151.00' Surf.Area= 200 sf Storage= 195 cf Peak Elev= 151.17' @ 11.96 hrs Surf.Area= 224 sf Storage= 232 cf (37 cf above start) Plug-Flow detention time= 43.7 min calculated for 0.072 af (94% of inflow) Center-of-Mass det. time= 0.7 min ( 835.0 - 834.4 ) Volume Invert Avail.Storage Storage Description #1 149.00'313 cf Custom Stage Data (Prismatic) Listed below (Recalc) Type II 24-hr 1 year Rainfall=1.88"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 3HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 149.00 20 0 0 150.00 85 53 53 151.00 200 143 195 151.50 270 118 313 Device Routing Invert Outlet Devices #1 Primary 151.00'10.0' long x 4.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.38 2.54 2.69 2.68 2.67 2.67 2.65 2.66 2.66 2.68 2.72 2.73 2.76 2.79 2.88 3.07 3.32 Primary OutFlow Max=1.72 cfs @ 11.96 hrs HW=151.17' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 1.72 cfs @ 0.99 fps) Summary for Pond 114P: Bioretension Swale/Basin Inflow Area = 1.050 ac, 0.00% Impervious, Inflow Depth = 0.87" for 1 year event Inflow = 1.73 cfs @ 11.96 hrs, Volume= 0.076 af Outflow = 0.05 cfs @ 14.88 hrs, Volume= 0.076 af, Atten= 97%, Lag= 174.9 min Primary = 0.05 cfs @ 14.88 hrs, Volume= 0.076 af Routing by Stor-Ind method, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Starting Elev= 147.50' Surf.Area= 2,000 sf Storage= 800 cf Peak Elev= 150.67' @ 14.88 hrs Surf.Area= 5,557 sf Storage= 2,747 cf (1,947 cf above start) Plug-Flow detention time= 790.8 min calculated for 0.058 af (76% of inflow) Center-of-Mass det. time= 530.4 min ( 1,365.4 - 835.0 ) Volume Invert Avail.Storage Storage Description #1 146.50' 1,600 cf Stone (Prismatic) Listed below (Recalc) 4,000 cf Overall x 40.0% Voids #2 148.50'51 cf Wetland Planting Soil (Prismatic) Listed below (Recalc) 2,550 cf Overall x 2.0% Voids #3 150.00' 2,868 cf Pond (Prismatic) Listed below (Recalc) 4,519 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 146.50 2,000 0 0 147.50 2,000 2,000 2,000 148.50 2,000 2,000 4,000 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 148.50 1,700 0 0 150.00 1,700 2,550 2,550 Type II 24-hr 1 year Rainfall=1.88"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 4HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 150.00 1,415 0 0 151.00 2,075 1,745 1,745 151.50 2,415 1,123 2,868 Device Routing Invert Outlet Devices #1 Primary 147.50'4.0" Round Culvert L= 30.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 147.50' / 147.10' S= 0.0133 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.09 sf #2 Device 1 147.50'1.0" Vert. Orifice/Grate C= 0.600 #3 Primary 151.00'10.0' long x 5.5' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.35 2.51 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.69 2.73 2.77 2.86 Primary OutFlow Max=0.05 cfs @ 14.88 hrs HW=150.67' (Free Discharge) 1=Culvert (Passes 0.05 cfs of 0.52 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.05 cfs @ 8.52 fps) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Pre Development Qp10QP10 13S Pre Dev Site SN001 89S SN001 115P Forebay 116P Bioretension Swale/Basin Routing Diagram for Homestead Prepared by Krebs & Lansing Consulting Engineers, Inc., Printed 2/23/2022 HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type II 24-hr 10 year Rainfall=3.20"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 2HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Summary for Subcatchment 13S: Pre Dev Site SN001 Runoff = 2.38 cfs @ 11.99 hrs, Volume= 0.117 af, Depth= 1.34" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Type II 24-hr 10 year Rainfall=3.20" Area (ac) CN Description * 1.050 79 Workbook 1.050 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.4 Direct Entry, Workbook Summary for Subcatchment 89S: SN001 Runoff = 2.94 cfs @ 11.97 hrs, Volume= 0.135 af, Depth= 1.54" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Type II 24-hr 10 year Rainfall=3.20" Area (ac) CN Description * 1.050 82 CN Modified 1.050 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.5 Direct Entry, From SW Workbook Summary for Pond 115P: Forebay Inflow Area = 1.050 ac, 0.00% Impervious, Inflow Depth = 1.54" for 10 year event Inflow = 2.94 cfs @ 11.97 hrs, Volume= 0.135 af Outflow = 2.94 cfs @ 11.97 hrs, Volume= 0.135 af, Atten= 0%, Lag= 0.2 min Primary = 2.94 cfs @ 11.97 hrs, Volume= 0.135 af Routing by Stor-Ind method, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Starting Elev= 151.00' Surf.Area= 200 sf Storage= 195 cf Peak Elev= 151.25' @ 11.97 hrs Surf.Area= 234 sf Storage= 248 cf (53 cf above start) Plug-Flow detention time= 26.6 min calculated for 0.130 af (97% of inflow) Center-of-Mass det. time= 0.6 min ( 833.2 - 832.6 ) Volume Invert Avail.Storage Storage Description #1 149.00'313 cf Custom Stage Data (Prismatic) Listed below (Recalc) Type II 24-hr 10 year Rainfall=3.20"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 3HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 149.00 20 0 0 150.00 85 53 53 151.00 200 143 195 151.50 270 118 313 Device Routing Invert Outlet Devices #1 Primary 151.00'10.0' long x 4.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.38 2.54 2.69 2.68 2.67 2.67 2.65 2.66 2.66 2.68 2.72 2.73 2.76 2.79 2.88 3.07 3.32 Primary OutFlow Max=2.93 cfs @ 11.97 hrs HW=151.25' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 2.93 cfs @ 1.20 fps) Summary for Pond 116P: Bioretension Swale/Basin Inflow Area = 1.050 ac, 0.00% Impervious, Inflow Depth = 1.54" for 10 year event Inflow = 2.94 cfs @ 11.97 hrs, Volume= 0.135 af Outflow = 0.42 cfs @ 12.22 hrs, Volume= 0.135 af, Atten= 86%, Lag= 14.6 min Primary = 0.42 cfs @ 12.22 hrs, Volume= 0.135 af Routing by Stor-Ind method, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Starting Elev= 147.50' Surf.Area= 2,000 sf Storage= 800 cf Peak Elev= 151.06' @ 12.22 hrs Surf.Area= 5,817 sf Storage= 3,524 cf (2,724 cf above start) Plug-Flow detention time= 683.0 min calculated for 0.116 af (86% of inflow) Center-of-Mass det. time= 520.2 min ( 1,353.4 - 833.2 ) Volume Invert Avail.Storage Storage Description #1 146.50' 1,600 cf Stone (Prismatic) Listed below (Recalc) 4,000 cf Overall x 40.0% Voids #2 148.50'51 cf Wetland Planting Soil (Prismatic) Listed below (Recalc) 2,550 cf Overall x 2.0% Voids #3 150.00' 2,868 cf Pond (Prismatic) Listed below (Recalc) 4,519 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 146.50 2,000 0 0 147.50 2,000 2,000 2,000 148.50 2,000 2,000 4,000 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 148.50 1,700 0 0 150.00 1,700 2,550 2,550 Type II 24-hr 10 year Rainfall=3.20"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 4HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 150.00 1,415 0 0 151.00 2,075 1,745 1,745 151.50 2,415 1,123 2,868 Device Routing Invert Outlet Devices #1 Primary 147.50'4.0" Round Culvert L= 30.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 147.50' / 147.10' S= 0.0133 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.09 sf #2 Device 1 147.50'1.0" Vert. Orifice/Grate C= 0.600 #3 Primary 151.00'10.0' long x 5.5' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.35 2.51 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.69 2.73 2.77 2.86 Primary OutFlow Max=0.40 cfs @ 12.22 hrs HW=151.06' (Free Discharge) 1=Culvert (Passes 0.05 cfs of 0.55 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.05 cfs @ 9.03 fps) 3=Broad-Crested Rectangular Weir (Weir Controls 0.35 cfs @ 0.58 fps) Pre Development Qp25QP25 107S Pre Dev Site SN001 108S SN001 117P Forebay 118P Bioretension Swale/Basin Routing Diagram for Homestead Prepared by Krebs & Lansing Consulting Engineers, Inc., Printed 2/23/2022 HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type II 24-hr 25 year Rainfall=3.82"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 2HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Summary for Subcatchment 107S: Pre Dev Site SN001 Runoff = 3.24 cfs @ 11.99 hrs, Volume= 0.159 af, Depth= 1.82" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Type II 24-hr 25 year Rainfall=3.82" Area (ac) CN Description * 1.050 79 Workbook 1.050 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.4 Direct Entry, Workbook Summary for Subcatchment 108S: SN001 Runoff = 3.90 cfs @ 11.97 hrs, Volume= 0.179 af, Depth= 2.05" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Type II 24-hr 25 year Rainfall=3.82" Area (ac) CN Description * 1.050 82 CN Modified 1.050 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.5 Direct Entry, From SW Workbook Summary for Pond 117P: Forebay Inflow Area = 1.050 ac, 0.00% Impervious, Inflow Depth = 2.05" for 25 year event Inflow = 3.90 cfs @ 11.97 hrs, Volume= 0.179 af Outflow = 3.89 cfs @ 11.97 hrs, Volume= 0.179 af, Atten= 0%, Lag= 0.2 min Primary = 3.89 cfs @ 11.97 hrs, Volume= 0.179 af Routing by Stor-Ind method, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Starting Elev= 151.00' Surf.Area= 200 sf Storage= 195 cf Peak Elev= 151.29' @ 11.97 hrs Surf.Area= 241 sf Storage= 260 cf (65 cf above start) Plug-Flow detention time= 21.3 min calculated for 0.175 af (98% of inflow) Center-of-Mass det. time= 0.6 min ( 824.9 - 824.3 ) Volume Invert Avail.Storage Storage Description #1 149.00'313 cf Custom Stage Data (Prismatic) Listed below (Recalc) Type II 24-hr 25 year Rainfall=3.82"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 3HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 149.00 20 0 0 150.00 85 53 53 151.00 200 143 195 151.50 270 118 313 Device Routing Invert Outlet Devices #1 Primary 151.00'10.0' long x 4.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.38 2.54 2.69 2.68 2.67 2.67 2.65 2.66 2.66 2.68 2.72 2.73 2.76 2.79 2.88 3.07 3.32 Primary OutFlow Max=3.89 cfs @ 11.97 hrs HW=151.29' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 3.89 cfs @ 1.33 fps) Summary for Pond 118P: Bioretension Swale/Basin Inflow Area = 1.050 ac, 0.00% Impervious, Inflow Depth = 2.05" for 25 year event Inflow = 3.89 cfs @ 11.97 hrs, Volume= 0.179 af Outflow = 2.30 cfs @ 12.05 hrs, Volume= 0.179 af, Atten= 41%, Lag= 4.5 min Primary = 2.30 cfs @ 12.05 hrs, Volume= 0.179 af Routing by Stor-Ind method, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Starting Elev= 147.50' Surf.Area= 2,000 sf Storage= 800 cf Peak Elev= 151.21' @ 12.05 hrs Surf.Area= 5,917 sf Storage= 3,844 cf (3,044 cf above start) Plug-Flow detention time= 527.2 min calculated for 0.161 af (90% of inflow) Center-of-Mass det. time= 415.2 min ( 1,240.2 - 824.9 ) Volume Invert Avail.Storage Storage Description #1 146.50' 1,600 cf Stone (Prismatic) Listed below (Recalc) 4,000 cf Overall x 40.0% Voids #2 148.50'51 cf Wetland Planting Soil (Prismatic) Listed below (Recalc) 2,550 cf Overall x 2.0% Voids #3 150.00' 2,868 cf Pond (Prismatic) Listed below (Recalc) 4,519 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 146.50 2,000 0 0 147.50 2,000 2,000 2,000 148.50 2,000 2,000 4,000 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 148.50 1,700 0 0 150.00 1,700 2,550 2,550 Type II 24-hr 25 year Rainfall=3.82"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 4HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 150.00 1,415 0 0 151.00 2,075 1,745 1,745 151.50 2,415 1,123 2,868 Device Routing Invert Outlet Devices #1 Primary 147.50'4.0" Round Culvert L= 30.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 147.50' / 147.10' S= 0.0133 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.09 sf #2 Device 1 147.50'1.0" Vert. Orifice/Grate C= 0.600 #3 Primary 151.00'10.0' long x 5.5' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.35 2.51 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.69 2.73 2.77 2.86 Primary OutFlow Max=2.29 cfs @ 12.05 hrs HW=151.21' (Free Discharge) 1=Culvert (Passes 0.05 cfs of 0.56 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.05 cfs @ 9.22 fps) 3=Broad-Crested Rectangular Weir (Weir Controls 2.24 cfs @ 1.07 fps) Pre Development Qp100QP100 93S Pre Dev Site SN001 94S SN001 119P Forebay 120P Bioretension Swale/Basin Routing Diagram for Homestead Prepared by Krebs & Lansing Consulting Engineers, Inc., Printed 2/23/2022 HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type II 24-hr 100 year Rainfall=4.78"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 2HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Summary for Subcatchment 93S: Pre Dev Site SN001 Runoff = 3.57 cfs @ 12.01 hrs, Volume= 0.185 af, Depth= 2.11" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Type II 24-hr 100 year Rainfall=4.78" Area (ac) CN Description * 1.050 73 Workbook 1.050 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.8 Direct Entry, Workbook Summary for Subcatchment 94S: SN001 Runoff = 4.49 cfs @ 11.98 hrs, Volume= 0.214 af, Depth= 2.44" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Type II 24-hr 100 year Rainfall=4.78" Area (ac) CN Description * 1.050 77 CN Modified 1.050 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.5 Direct Entry, From SW Workbook Summary for Pond 119P: Forebay Inflow Area = 1.050 ac, 0.00% Impervious, Inflow Depth = 2.44" for 100 year event Inflow = 4.49 cfs @ 11.98 hrs, Volume= 0.214 af Outflow = 4.49 cfs @ 11.98 hrs, Volume= 0.214 af, Atten= 0%, Lag= 0.2 min Primary = 4.49 cfs @ 11.98 hrs, Volume= 0.214 af Routing by Stor-Ind method, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Starting Elev= 151.00' Surf.Area= 200 sf Storage= 195 cf Peak Elev= 151.32' @ 11.98 hrs Surf.Area= 245 sf Storage= 266 cf (71 cf above start) Plug-Flow detention time= 17.9 min calculated for 0.209 af (98% of inflow) Center-of-Mass det. time= 0.6 min ( 829.7 - 829.1 ) Volume Invert Avail.Storage Storage Description #1 149.00'313 cf Custom Stage Data (Prismatic) Listed below (Recalc) Type II 24-hr 100 year Rainfall=4.78"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 3HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 149.00 20 0 0 150.00 85 53 53 151.00 200 143 195 151.50 270 118 313 Device Routing Invert Outlet Devices #1 Primary 151.00'10.0' long x 4.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.38 2.54 2.69 2.68 2.67 2.67 2.65 2.66 2.66 2.68 2.72 2.73 2.76 2.79 2.88 3.07 3.32 Primary OutFlow Max=4.48 cfs @ 11.98 hrs HW=151.32' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 4.48 cfs @ 1.40 fps) Summary for Pond 120P: Bioretension Swale/Basin Inflow Area = 1.050 ac, 0.00% Impervious, Inflow Depth = 2.44" for 100 year event Inflow = 4.49 cfs @ 11.98 hrs, Volume= 0.214 af Outflow = 3.34 cfs @ 12.04 hrs, Volume= 0.214 af, Atten= 26%, Lag= 3.5 min Primary = 3.34 cfs @ 12.04 hrs, Volume= 0.214 af Routing by Stor-Ind method, Time Span= 1.00-120.00 hrs, dt= 0.01 hrs Starting Elev= 147.50' Surf.Area= 2,000 sf Storage= 800 cf Peak Elev= 151.27' @ 12.04 hrs Surf.Area= 5,955 sf Storage= 3,970 cf (3,170 cf above start) Plug-Flow detention time= 451.9 min calculated for 0.195 af (91% of inflow) Center-of-Mass det. time= 361.6 min ( 1,191.2 - 829.7 ) Volume Invert Avail.Storage Storage Description #1 146.50' 1,600 cf Stone (Prismatic) Listed below (Recalc) 4,000 cf Overall x 40.0% Voids #2 148.50'51 cf Wetland Planting Soil (Prismatic) Listed below (Recalc) 2,550 cf Overall x 2.0% Voids #3 150.00' 2,868 cf Pond (Prismatic) Listed below (Recalc) 4,519 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 146.50 2,000 0 0 147.50 2,000 2,000 2,000 148.50 2,000 2,000 4,000 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 148.50 1,700 0 0 150.00 1,700 2,550 2,550 Type II 24-hr 100 year Rainfall=4.78"Homestead Printed 2/23/2022Prepared by Krebs & Lansing Consulting Engineers, Inc. Page 4HydroCAD® 10.00 s/n 06429 © 2013 HydroCAD Software Solutions LLC Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 150.00 1,415 0 0 151.00 2,075 1,745 1,745 151.50 2,415 1,123 2,868 Device Routing Invert Outlet Devices #1 Primary 147.50'4.0" Round Culvert L= 30.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 147.50' / 147.10' S= 0.0133 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.09 sf #2 Device 1 147.50'1.0" Vert. Orifice/Grate C= 0.600 #3 Primary 151.00'10.0' long x 5.5' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.35 2.51 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.69 2.73 2.77 2.86 Primary OutFlow Max=3.32 cfs @ 12.04 hrs HW=151.26' (Free Discharge) 1=Culvert (Passes 0.05 cfs of 0.56 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.05 cfs @ 9.29 fps) 3=Broad-Crested Rectangular Weir (Weir Controls 3.27 cfs @ 1.24 fps)