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Home My WebLink About992600001 Drainage Report I I I I I I I I I I I I I I I I I I I DRAINAGE, EROSION, AND SEDIMENT CONTROL PLAN for 247 Franks Lane, Parcel No 992600001 Prepared for: NORTHWESTE TER IT..""7 Peabo '....~---...._," ,,-. D.EP1. OF COMMUNITY DEVELOPMENT I I I I I I I I I I I I I I I I I I I DRAINAGE, EROSION, AND SEDIMENT CONTROL PLAN Prepared For Seahome Services, Inc. April 2006 For the Property Described as 247 Franks Lane, Tax # 992600001 Section 36, Township 21 North, Range 1 West, W.M. Jefferson County, Washington Prepared by NORTHWESTERN TERRITORIES, INC. 717 S. Peabody Street Port Angeles, Washington 98362 Phone 360-452-8491 Fax 360-452-8498 Web Site www.nti4u.com E-mail info@nti4u.com ".' ,I.', 1 I I I I I I I I I I I I I I I I I I I SEAHOME SERVICES, INC. PROJECT 247 FRANKS LANE THORNDYKE VICINITY MAP ft NORTHWESTERN TERRITORIES, INC. fngineers - Land Surveyors - Geologists Construction Inspection - Moleriols Testing NT I 717 SOUTH PEABODY, PORT ANGELES, WASHINGTON 98362, (360) 452-8491 I I I I I I I I I I I I I I I I I II II Drainage, Erosion, and Sediment Control Plan for Seahome Services, Inc., Project Located at 247 Franks Lane, Tax # 992600001 247 Franks Lane Area Map III I I I I I I I I I I I I I I I I I I I Drainage, Erosion, and Sediment Control Plan for Seaborne Services, Inc., Project Located at 247 Franks Lane, Tax # 992600001 247 Franks Lane Neighborhood Map IV I I I I I I I I I I I I I I I I I I I Drainage, Erosion, and Sediment Control Plan for Seahome Services, Inc., Project Located at 247 Franks Lane, Tax # 992600001 Site Map of 247 Franks Lane v I I I I I I I I I I I I I I I I I I I 0 I t "O-,Ol t~ I. I~ '" lcD-ell 1 0 ~ I (X) \ I~ (i\ '" ... ... '" z '" '" '" :;: D a " u Cl. .., W W '" :3 '" '" ~ ... 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OJ OJ OJ '" " OJ Z '" z I Q z .. ...J "'W z"" I _w ....'" "'u _z X" wu I z I 0 I-< I-- U w I C/) ~ I-< I <l: I-- C/) I I I I I I I I I I I I I I I I I I I Drainage, Erosion, and Sediment Control Plan for Seabome Services, Inc., Project Located at 247 Franks Lane, Tax # 992600001 Erosion and Sediment Control Plan Notes: 1. Install silt fencing along brow of slope (shown with dashed line above) below any earth disturbing activities. Extend silt fencing 15 feet laterally beyond limits of exposed soil. Maintain silt fencing until revegetation has occurred. 2. Install additional silt fencing just above the line of ordinary high water only if work will expose soils on the slope above. 3. Route all runofTfrom roof drains to the tightline pipe to be routed down the stairs per the drainage report. 4. Follow recommendations of the text of the Erosion and Sediment Control Plan ix I I I I I I I I I I I I I I I I I I I STANDARD TEMPORARY EROSION AND SEDIMENT CONTROL PLAN NOTES The following notes are recommended as standard language for temporary erosion and sediment control plans required under the Jefferson County Unified Development Code. The use of these notes will facilitate the review and approval of these plans by the Jefferson County Public Works Department. . All erosion and sediment control Best Management Practices shall be selected, constructed, and maintained in accordance with the Washington Department of Ecology Stonnwater ManaQement Manual for Western Washimrton (current edition). . The construction and maintenance of erosion and sediment control measures shall be the responsibility of the contractor. The contractor shall not deviate from the approved plans without prior approval from the Jefferson County Public Works Department. The contractor shall have a set of approved plans on the site whenever construction is in progress. . The erosion and sediment control measures depicted on this plan are minimum requirements to meet anticipated site conditions. As conditions dictate during construction, the contractor shall implement additional measures as necessary to ensure erosion and sediment controL . Construction vehicle access shall be limited to one route, whenever possible. Quarry spalls or crushed rock shall be applied to the access in order to prevent sediment from being transported on to roads. If this should occur, roads shall be cleaned thoroughly by shoveling or sweeping. . Clearing shall be phased so that only areas that are being worked are exposed. All exposed and unworked soils shall be stabilized by appropriate Best Management Practices. From October I through April 30, unworked soils shall not be left exposed for more than 2 days. From May I through September 30, unworked soils shall not be left exposed for more than 7 days. . All erosion and sediment control measures shall be maintained in a satisfactory condition until such time as land disturbing activities are completed and the potential for onsite erosion has passed. . The contractor shall request inspection of temporary erosion and sediment control measures by the Jefferson County Public Works Department [(360) 385-9160] as soon as practicable after installation. x I I I I I I I I I I I I I I I I I I I DRAINAGE, EROSION, AND SEDIMENT CONTROL PLAN for PARCEL 976500009 ABSTRACT This project consists of the construction of a beach access stair system and related work on a 100 foot wide parcel at 247 Franks Lane, Quilcene, Washington. This plan provides for the construction of a tightline pipe to convey stormwater runoff from the existing improvements. The pre-development runoff is not calculated since the system will discharge directly to marine waters. The post-development runoff is estimated based on a standard 24 hour storm having mean recurrence intervals of25 years. Post-development runoff is used to design the tightline stormwater pipe. Construction phase erosion and sediment control measures are proposed to prevent soil from leaving the site during construction of the improvements. A site plan showing erosion control measures is included at the beginning of this report. The following BMPs shall be implemented in addition to any that may later be necessary due to changing or unforeseen site conditions. 1. Silt fencing shall be installed below the limits of any work which will expose soil to the elements for more than 24 hours. The location of the silt fencing is shown on the Erosion and Sediment Control Plan map included at the beginning of this report. 2. Additional silt fencing shall be installed just above the line of ordinary high water if any work will expose soils on the slope above the beach for more than 24 hours. 3. Existing runoff from roof drains shall be routed to the tightline pipe to be constructed down the beach access stair system per this plan. The stair assembly shall include a six inch diameter tightline pipe to transport storm water runoff from the uplands to discharge immediately above the line of ordinary high water. The pipe shall be rigidly secured to the stair assembly. The discharge point shall be at ground level into a basin of quarry spalls for energy dissipation. 4. The recommendations of the text of the Erosion and Sediment Control Plan shall be followed. xi I I I I I I I I I I I I I I I I I I I Drainage, Erosion, and Sediment Control Plan for Seabome Services, Inc., Project Located at 247 Franks Lane, Tax It 992600001 CONTENTS I. PROJECT OVERVIEW........................................................................1 A. Project Description......................................................................2 B. Existing Site Conditions.............................................................2 1. Topography................ ............ .............. ..................................2 2. Vegetation... ............................................. ...... .... ..... ... ... .........4 3. Drainage... ........................ ................. .... .......... .......................6 C. Adjacent Areas....... ............................. .............. ..........................7 II. DESIGN CRITERIA........................................................................... 7 A. Soils..... ........................ .................. ...... ......... ......... ....... ...... .........7 B. Rainfall.............. ...................................................... ........... .........9 C. Hydrologic Model....... .... .................. ........................ ....... ..... ... ..10 D. Time of Concentration..............................................................10 1. Predevelopment Condition..................................................11 2. Predevelopment Time ofConcentration.............................13 3. Post-development Condition...............................................13 III. RUNOFF ..........................................................................................13 A. Pre-development Runoff. ........................... ...... ..................... ... .13 B. Post-development Runoff.. ............ .... ........................................14 C. Mitigation. .... ................................................. .................. .... ......14 IV. EROSION AND SEDIMENT CONTROL PLAN ...........................14 A. Site Specific Construction Phase BMPs..................................15 B. Stabilization and Sediment Trapping (Erosion and Sediment Control Requirement Number 1)............................................15 1. Stabilization of Exposed Soils.............................................16 2. Sediment Trapping.............................................................. 18 C. Delineate Clearing and Easement Limits (Erosion and Sediment Control Requirement Number 2)...........................20 D. Protection of Adjacent Properties (Erosion and Sediment Control Requirement Number 3)............................................20 E. Timing and Stabilization of Sediment Trapping Measures (Erosion and Sediment Control Requirement Number 4).....21 1. Timing ofInstallation ofBMPs..........................................21 2. Stabilization of slopes of structural BMPs.........................21 F. Cut and Fill Slopes (Erosion and Sediment Control Requirement Number 5)......................................................21 xii I I I I I I I I I I I I I I I I I I I G. Controlling Off-Site Erosion {Erosion and Sediment Control Requirement Number 6)................... ... .................. ................ .22 H. Stabilization of Temporary Channels and Outlets {Erosion and Sediment Control Requirement Number 7)....................22 I. Underground Utility Construction {Erosion and Sediment Control Requirement Number 9)............................................22 J. Construction Access Routes {Erosion and Sediment Control Requirement Number 10)...... ........................................ ..... ....23 K. Removal of Temporary BMPs {Erosion and Sediment Control Requirement Number 11).................... .......... .......... ...............24 L. Dewatering Construction Sites {Erosion and Sediment Control Requirement Number 12)..........................................24 M. Control of Pollutants Other than Sediment {Erosion and Sediment Control Requirement Number 13).........................24 1. Control of Toxic Substances................................................25 2. Petroleum Spills........ ...................... ................. ....... ...... ......25 N. Maintenance {Erosion and Sediment Control Requirement Number 14).................................................................. ............26 O. Financial Responsibility.............................. .......... ........ .... .......27 xiii I I I I I I I I I I I I I I I I I I I Drainage, Erosion, and Sediment Control Plan for Seabome Services, Inc., Project Located at 247 Franks Lane, Tax # 992600001 Photo 1 I. PROJECT OVERVIEW This project consists of the construction of a beach access stair system and related work on a single parcel at 247 Franks Lane, Quilcene, Washington. This plan also provides for the construction of a tightline pipe to convey stonnwater runoff from the existing roof drains. Photo 1 front of the home which is located on the eastern end of the parcel. The existing layout of the site is shown on the site map included at the beginning of this report. A geotechnical report for the site was prepared by this office and provides additional infonnation about the site. 1 I I I I I I I I I I I I I I I I I I I A. Project Description This project consists of the construction of a beach access stair system. The drainage, sediment and erosion control features of the plan are directed toward the stair system but they also provide for conveyance of roof water from existing structures on the site. B. Existing Site Conditions The following summary of site conditions represents existing conditions. 1. Tbpography The site is somewhat long and narrow with the axis oriented east and west as shown on the Area, Neighborhood, and Site Maps included at the beginning of this report. The geotechnical report prepared by this office discusses the topography in more detail. The ground generally slopes to the east, toward the beach. FiI!11re 1 Figure 1 is an excerpt from the USGS Topo map of the area. Note the gentle and uniform slope to the east. 2 I I I I I I I I I I I I I I I I I I I Photo 2 Photo 2 shows the general area of 247 Franks Lane, which is indicated by the arrow in the photo. The gently sloping ground shown in Photo 2 tenninates abruptly at the moderately high coastal bluff shown in Photo 3. Photo 3 Access to the bottom of the bluff is provided by an existing set of stairs. These stairs are shown in Photos 3 and 4. These stairs will be replaced per this project. 3 . . I I I I I I . . I I I I I . . . '. Photo 4 2. Vegetation The westernmost portion of the site is heavily vegetated with natural vegetation as shown on the neighborhood map included at the beginning of this report. The uplands portion immediately adjacent to the top of the bluff is covered with healthy lawn and landscaping as shown in Photo 5. Photo 5 4 I I I I I I I I I I I I I I I I I I I Vegetation on the face of the bluff is a mix of natural vegetation and ivy as shown in Photo 6. Photo 6 The vegetation extends to the line of ordinary high water as seen in Photo 7. Photo 7 , 5 I I I I I I I I I I I I I I I I I I I 3. Drainage The site presently drains easterly down the uplands slope and over the bluff. Most of the flow from the areas above the developed portion of the parcel goes through an 18 inch diameter culvert which dumps over the bluff on the south side of the existing house. This culvert is obscured by very heavy brush but can be seen in the background of Photo 8. Tk \h, r c..\lL~ac- r...s. LOG~d 0"'; A() da..1?'E'" ptGpr.~T~ Photo 8 Flows from this culvert have eroded the bluff back but the area below (See Photo 9) has become stabilized and further erosion appears to have been stopped. Thi.s 0 -07 0"'" 711.0 itA .k.e;zE.'iT frqf'C-t"y Photo 9 6 I I I I I I I I I I I I I I I I I I I Roof runoff apparently goes over the bluff via the smaller diameter pipes shown in Photo 10. These pipes have failed and erosion of the bluff below has resulted. Photo 10 Drainage across the lawn and landscaped portions of the lower portion of the uplands is primarily by sheet flow which flows down the bluff. C. Adjacent Areas . The site is surrounded by rural residential lands on the north and south sides. Thorndyke Road, a County road, lies on the west side of the parcel. Hood Canal fonns the eastern side of the parcel. The maps included at the beginning of this report show good overviews of the neighborhood. II. DESIGN CRITERIA The following criteria are specific to this project site and will not apply to other properties, even those that may be nearby. A. Soils The site may be found on map number 62 of the Soil Survev of Jefferson Countv Area, published by the U. S. Soil Conservation Service, a portion of which is reproduced here as Figure 2. 7 I I I I I I I I I I I I I I I I I I Figure 2 Figure 2 can be compared with the Area Maps at the beginning of this report for orientation. Map number 62 predicts that the soils on this site are type cre, Cassolary sandy loam on slopes ranging between 0 and 15 percent. The Soil Survev of Jefferson Countv Area describes Cassolary sandy loam as being well drained soils on uplands formed of reworked glacial and marine sediments. The well drained descriptor may not agree well with the soils on the lower, developed part of the parcel, near the bluff where permeability appears to be less rapid. Cassolary soils belong to hydrologic group C, which is only a moderately well drained classification and which agrees with the findings of the field ! I 8 I I I I I I I I I I I I I I I I I I I investigation. This report assumes that the soils are Cassolary soils. Additional discussion of the soils can be found in the geotechnical report. B. Rainfall The total amount of precipitation falling over a 24 hour period during a stonn having a mean recurrence interval of 2 years, will be 2.8 inches. This information was taken from a 2 year, 24 hour Isopluvial Map published by the U.S. Soil Conservation Service, a portion of which is reproduced here as Figure 3. The project location is marked on the map. 26N A ", ~ 15:!0 " \ \ --....., \ \ lW ISOPLUVIAlS OF 2-YEAR 24-HOUR PRECIPiTATION IN TENTHS OF AN INCH Figure 3 The isopluviallines represent total precipitation in 24 hours, in tenths of inches. 2 year rainfall data is used in the calculation of times of concentration for the site. The total amount of precipitation falling over a 24 hour period during a stonn having a mean recurrence interval of 25 years, will be 5.0 inches. This information was taken from a 25 year, 24 hour Isopluvial Map published by the U.S. Soil Conservation Service, a portion of which is reproduced here as Figure 4. The project location is marked on the map. 9 I I I I I I I I I I I I I I I I I I I 61) J1N 6S~'"" ~ 50t5 4,0 ~5 \ . 2~ .1,O\. 20 , 26M \.;, JON llO~ }'-"\ ,\ \~ Of:,. \ --..... . 29N'~' , '"----......... \. ....20 ... \. , "!"l 27N \ 10 ^' ->.r- \j l ,C'"1101Xt "\ " -" ---. j (i4d--, \ 90' 85 . I - L/') I.... ,\ , \ \65 '70 lOW 9W BW 7W 6W 5W 4W IW fSOPLUVIALS OF 25-YEAR 24-HOUR PRECIPITATION IN TENTHS or AN INcH Figure 4 The rainfall distribution is assumed to be a Type IA distribution per standard practice in the area. C. Hydrologic Model Because hydrologic and hydraulic calculations are only performed for the purpose of sizing the tightline pipe system, there is no need for a continuous hydrologic simulation. Only the peak flow is needed. This plan uses a hydrograph based method of calculating runoff which is described in Urban Hydrology for Small Watersheds, Technical Release No. 55, and the Western Washington Supplement to Technical Release No. 55, both published by the U. S. Soil Conservation Service. This same type of method is given in the King County Surface Water Design Manual, published by the King County Public Works Department, and the 1992 Stormwater Management Manual for the Puget Sound Basin (The Technical Manual) published by the Washington State Department of Ecology. This method yields runoff volumes that are significantly different from those determined using the rational method. This plan uses the suggested runoff curve numbers given in Table 2-2a of Technical Release No. 55. D. Time of Concentration The length of time that it takes a drop of rainfall to travel from the uppermost point of a basin to the point of discharge from the basin, or to the point where 10 I I I I I I I I I I I I I I I I I I I flows are to be calculated, is referred to as the time of concentration (Tc). This is the sum of the time it takes for runoff to flow across the various types of flow channels as it crosses the basin. Since most flow from the upper, wooded portions of the parcel are routed to the beach via the culvert shown in Photo 8, these predevelopment calculations assume that the basin begins at the upper portion of the lawnllandscaped portion and end at the top of the bluff. The following calculations are per Section 1II-1.4.2, pages III-I-I3 through III-I- 16, of the Washington State Department of Ecology's STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND BASIN. THE TECHNICAL MANUAL, (DOE). 1. Predevelopment Condition The time of concentration is first determined for the existing condition of the basin. a. Unconcentrated Flow Immediately after falling to the ground, rainwater initially travels as unconcentrated sheet flow for a period of time (Tt) calculated by: 0.80 0.42 (NsL) Tt = -------------------- = 5.49 min 0.527 0.4 (P2) (SO) Where: Ns = 0.240 P2 = 2.8 SO = 0.0500 L= 50 = Sheet flow Manning's n (DOE Table III-I.4) = 2 yr, 24 hr rainfall (in) = Slope of flow path (ft/ft) = Length (L) of flow path (ft) 11 I I I I I I I I I I I I I I I I I I I b. Shallow Concentrated Flow As sheet flows run together and become concentrated, they travel as shallow concentrated flow for a period of time (Tt) calculated by: L Tt = -------------------- = 0.54 min 60 Ks SQRT(SO) Where: Ks = 11 SO = 0.0800 L = 100 = Velocity factor (Ks) (per DOE Table I1I-1.4) = Slope of flow path (ftlft) = Length (L) of flow path (ft) c. Open Channel (Intermittent) Flow Flows next travel through intermittent open channels for a period of time (Tt) calculated by: L Tt = . - . - . - . - . - . = 0.35 min 60 Kc SQRT(SO) Where: Kc = 17 SO = 0.0800 L = 100 = Velocity factor (Kc) (DOE Table I1I-1.4) = Slope of flow path (ft/ft) = Length (L) offlow path (ft) 12 I I I I I I I I I I I I I I I I I I I 2. Predevelopment Time of Concentration As noted above, the time of concentration (Tcl is the sum of the time it takes for runoff to flow across the various types of flow channels as it crosses the basin. For the predevelopment condition: Tc = the sum of the various Tt's = 6.37 min This is rounded to 6 min for use in further calculations. 3. Post-development Condition The time of concentration is next determined for the proposed, post-developed condition of the basin. There is little change in time of concentration from the predeveloped to the postdeveloped condition since most changes in land use will occur in areas where flows are already relatively rapid, allowing little opportunity for the increased flow velocities that will reduce the time of concentration. Because of these conditions, the postdevelopment time of concentration is assumed to be the same as the predevelopment time of concentration. III. RUNOFF These calculations are based on runoff from roofs having an assumed aggregate surface area of 5,000 square feet. While not necessary for the purposes of this report, pre-development runoff was calculated for the site. These values are reported but calculations are not included. Full calculations for post-development flow at the 25 year level are included in Appendix I. A. Pre-development Runoff A catalog of assumed pre-development conditions and calculations of the pre- development, weighted runoff curve numbers is included in Appendix I. These are the conditions that were assumed to prevail before development of the site. Under these conditions, the site has a weighted runoff curve number of 81. Complete calculations of the pre-development runoff are contained in Appendix I. The pre-development runoff is calculated to be 0.0895 cfs for the 25-year storm. 13 I I I I I I I I I I I I I I I I I I I B. Post-development Runoff A catalog of assumed post-development conditions and calculations of the post- development, weighted runoff curve numbers is also included in Appendix 1. These are the conditions that will prevail after development of the site. Under these conditions, the site will have a weighted runoff curve number of 98. Complete calculations of the post-development runoff are contained in Appendix 1. The post-development runoff is calculated to be 0.0.145 cfs for the 25-year storms, an increase from the predevelopment rate. C. Mitigation Construction phase erosion and sediment control measures are proposed to prevent soil from leaving the site during construction of the improvements. A site map for erosion control measures is included at the beginning of this report. To mitigate increased levels of runoff from the future full development of this parcel, and to provide a higher level of protection against erosion of the marine slope, existing runoff from roof drains shall be routed to the tightline pipe to be constructed down the beach access stair system per this plan. Runoff from future structures shall also be routed to the same tightline pipe down the beach access stair system. Design (sizing) calculations, including flood routing calculations, are included in Appendix 1. The stair assembly shall include a six inch diameter tightline pipe to transport stormwater runoff from the uplands to discharge immediately above the line of ordinary high water. The pipe shall be rigidly secured to the stair assembly. The discharge point shall be at ground level into a basin of quarry spalls for energy dissipation. To mitigate potential erosion and sediment impacts, the requirements of the erosion and sediment control plan shall be followed. Site specific mitigation measures are listed near the beginning of the erosion and sediment control plan. General guidelines and recommendations are in following sections. IV. EROSION AND SEDIMENT CONTROL PLAN This portion of the plan was prepared with the goal of preventing damage to adjoining or downstream properties due to erosion and sediment deposition and preventing the degradation of the quality of the receiving waters during the construction phase of this project. To ensure that the provisions of this Erosion and Sediment Control Plan are followed during construction, the complete text of this Erosion and Sediment Control 14 I I I I I I I I I I I I I I I I I I I Plan should be included in the construction plans for this project. Where formal construction plans will not be prepared for all or portions of the work, a copy of this document should be made available to the contractor and appropriate subcontractors. Subcontractors that will not be receiving copies should be made aware of the plan's existence and advised where copies can be obtained. Water quality controls. commonly referred to as Best Management Practices, or BMPs, are necessary to prevent three distinct types of impacts. The first consists of damage done as the result of soils being taken up by running water. This type of damage typically consists of rilling, rutting and loss of topsoil. The second type of damage is the degradation of water quality that occurs as the water transports the smaller soil particles. The third type of damage occurs when the running water reduces its velocity and drops the suspended soils. The Erosion and Sediment Control features (BMPs) of this plan are designed to address all three types of damage with the emphasis on preventing the initial soil uptake. Successful prevention of soil uptake will also prevent damage caused by degradation of water quality and by soil deposition. While the measures described below for preventing soil uptake should theoretically prevent any removal of soil, common sense advises that additional measures will be necessary and indeed, the DOE Manual requires additional measures. These additional measures will allow deposition of transported soils under controlled conditions before flows leave the project site or enter the receiving waters. The site specific types of BMPs and their locations are described immediately below in sub-section A. Specific details of the BMPs and the standards required by the DOE manual follow as sub-sections B - O. A. Site Specific Construction Phase BMPs Site specific BMPs are listed in the Mitigation section above. Those BMPs shall be implemented in addition to any that may later be necessary due to changing or unforeseen site conditions. It is expected that minor adjustments, especially the installation of additional BMPs where an unexpected need arises, will be necessary during the construction phase of this project. For this reason, discussions of various BMPs that are not specifically required are included below. These BMPs should be considered as being held in ready reserve against the possibility that they will be needed. The following subsections discuss the various BMPs that may be incorporated in this plan. Reasons for their use, limitations and benefits associated with specific BMPs, and additional information are provided. B. Stabilization and Sediment Trapping (Erosion and Sediment Control Requirement Number 1) These requirements are to be considered general in nature and provide a framework for deciding when and where various BMPs should be utilized. They 15 I I I I I I I I I I I I I I I I I I I are intended to provide guidance in quickly selecting BMPs for use in unexpected situations. They apply to both soils that are not yet at final grade and to those that are at final grade, including soil stockpiles. 1. Stabilization of Exposed Soils The stabilization of exposed soils is the single most important element of this plan. If exposed soils are protected such that soil particles are not picked up by running water, erosion will not occur. Protection of exposed soil consists of four main areas of effort. a. Minimize Disturbance of Vegetation Existing vegetation on the site comprises the best overall protection against erosion. To protect this resource and to keep the risk of erosion at a minimum, clearing and grading activities outside of the areas necessary to construct the improvements shall be kept to an absolute minimum. Patches of existing vegetation that are within the clearing/grading limits and may be left intact without hindering the project, shall be left alone whenever possible. Care shall be taken that existing vegetation is left intact wherever possible around the perimeter of the project and particularly along the lower side of the project. Vegetation in drainage corridors and immediately below soil disturbing activities is the most valuable and as such is to be provided with the most protection. b. Minimize the Length of Time the Soil is Unprotected Where grading is necessary for construction activities, the grading should be delayed as long as reasonably possible to minimize the length of time that the soil is exposed to the elements. Where exposure of bare soil is necessary to accomplish certain portions of the work, such portions of the work should be completed promptly in order to reduce the chance of an erosive rainfall event catching the soil unprotected. c. Ensure Prompt Revegetation of Disturbed Areas Every effort shall be made to ensure a healthy stand of protective vegetation is established as soon as possible. Reseeding of areas which are to be planted with grass shall be accomplished within 14 days if grading operations are completed within a planting season. If grading operations are completed outside of a planting season, reseeding shall occur within 7 days following the beginning of the next planting season. If substantial portions of the project are ready for reseeding at the beginning of or during a planting season, such portions may be promptly reseeded without waiting for completion of work on other portions of the project. 16 I I I I I I I I I I I I I I I I I I I Planting seasons are considered to be between March 1 and May 15 and between August 15 and October 1 where irrigation is impractical. Where irrigation is practical, the planting season is considered to be between March 1 and October 1. The following seed mix has been tested and found to be adequate for use for erosion control and for slope stabilization in Western Washington: Seed Type Percent by Weight Chewing Fescue 40 Colonial Bentgrass, Var. Astoria 10 Perennial Rye 40 White Clover 10 100 Other mixes, selected with regard for the soils, uses of the site, method of application, and expected weather may be used if desired. The recommendations of the seed supplier should be sought and strongly considered in selecting a mix. If the season or construction scheduling will not allow prompt revegetation of an area where construction activities have been completed, the area should be covered with plastic sheeting, straw, mulch or other covering chosen to match the situation and with due regard for the length of time that the area is expected to remain uncovered. d. Protective Coverings Protective coverings are highly recommended for application to exposed soils that are not being actively worked for an extended period of time. An extended period of time is considered to be 2 days between October 1 and April 30 or 7 days between May 1 and September 30. Protective coverings include plastic sheeting, straw, mulch, commercial sod and other coverings. The particular type of protective covering used should be chosen based on the steepness of the slope of the area to be covered, the size of the area to be covered, the time of year, the length of time the covering will remain, proximity to wetlands or other sensitive areas, the amount of existing vegetation between the exposed soil and the downhill project boundary, cost, and the visual impact of the covering. The best covering is existing vegetation, which should be disturbed as little as possible. Commercial sod is the next best covering but its use is often precluded by cost. Clear plastic sheeting is suitable for steep slopes but is difficult to apply and maintain in moderate to high winds. Black plastic sheeting is not appropriate during growing seasons except for short periods oftime. Loose straw, either straight from bales or shredded, 17 I I I I I I I I I I I I I I I I I I II makes an adequate ground covering on gentle to moderately steep slopes (no steeper than 2 horizontal to 1 vertical) if it is wet to the point of limpness. Straw is generally effective where the distance from the top to the toe of the slope is no more than 100 feet. Early application of gravel bases, pavements, and special landscaping items such as washed rock over plastic sheeting is considered to be a suitable protective covering where otherwise required. 2. Sediment Trapping Stonnwater runoff from areas of exposed soil shall not be pennitted to leave the project site without first having passed through an appropriate sediment trapping system or device. The type of sediment trap should be chosen based on the potential for erosion from exposed soils, the expected velocity and depth of flows, the proximity to downstream sensitive areas, and the length of time that the upstream soils will remain exposed to the elements. a. Sheet Flow Through Grassy or Heavily Vegetated Areas Runoff from exposed slopes that are less than 150 feet from top to bottom (measured along the slope) can be adequately treated by routing flows through bands of dense grass or other heavy vegetation. The vegetated band should be a minimum of one fifth as wide as the width of the exposed slope, but no narrower than 10 feet. For example, a band of exposed soil 75 feet wide should have a minimum of 15 feet of dense grass for sediment trapping. The vegetated band width above is for a slope no steeper than 10 percent. Where the slope of the vegetated area is between 10 and 20 percent, add 50 percent to the minimum width. Where the slope is greater than 20 percent, the minimum width should be doubled. For this type of sediment trapping system to be effective, flows must cross the vegetated area in sheet flows. If flows are expected to arrive at the vegetated band in concentrated flows, creation of a small artificial delta may be necessary to force a sheet flow. 18 I I I I I I I I I I I I I I I I I I I b. Grassy Swales Grassy swales are used to treat runoff from larger areas than sheet flows across bands of vegetation. Although grassy swales are usually thought of as pennanent features, they can often be utilized during the construction phase. Unfortunately, there is usually insufficient time before the main construction effort to reshape landfonns to provide the necessary slopes, widths, etc., and grow vegetation in the swale. Either an area must be found that is already vegetated and that meets the minimum requirements for a grassy swale or commercial sod must be placed along the sides and bottoms of the swale immediately after the swale is constructed. The following standard requirements for grassy swales were taken from the Draft Stonnwater Guidelines published by the Washington State Department of Fisheries in 1990 and are recommended for use here due to their simplicity. More specific design criteria are more appropriate for use on large or complex sites. i. Soils Gravelly and coarse sandy soils should be avoided in order to maximize water contact with vegetation and the soil surface. ii. Design Criteria The grassy swale. should be designed based on a two-year, 24-hour peak flow and the following: (A) Velocity Velocities should be less than 1.50 feet per second. (B) Depth of Flow The flow depth should be less than 4 inches. (C) Slope The longitudinal slope should average two to four percent. Rock or log check dams or terraces should be installed as necessary to achieve slopes of less than four percent. iii. Dimensions Grassy swales should be located to obtain maximum length. If less than 200 feet long, the width should be increased by an amount proportional to the reduction below 200 feet in order to obtain the same area of vegetation contact. IV. Side Slopes Side slopes should be no steeper than three horizontal to one vertical. 19 I I I I I I I I I I I I I I I I I I I c. Interceptor Swales Interceptor swales are shallow trenches constructed with a single pass of a large dozer equipped with one to three ripper teeth. The preferred configuration of ripper teeth for construction of interceptor swales is two teeth positioned on the outside of the ripper assembly. This type of swale construction will tear through existing sod without removing it. Leaving the sod in place will protect against erosion of the swale bottom on steeper slopes. Swales thus constructed are intended to intercept sheet flows and infiltrate them into the soil. When flows are greater than can be infiltrated, the swales will provide a path for runoff of excess flows. Such excess flows will run along the swale until they are either infiltrated or they enter interceptor ditches. Interceptor swales are especially effective adjacent to property lines which run more or less straight up and down a slope and where only sheet flows are to be intercepted. In order to be effective, the surface of the ground must not be regraded during the life of the swale. Grading or blading of the surface of these swales will defeat their purpose. Construction of interceptor swales causes only minimal disruption of the ground contours. For this reason the swales need not be removed or otherwise treated at the end of their usefulness. d. Other Sediment Trapping Devices and Systems Many other effective sediment trapping systems and devices are listed in Table 11-2.1 of the 1992 DOE Manual. Complete details and descriptions of them are included elsewhere in the DOE Manual. They should be used where appropriate and as described in the Manual. C. Delineate Clearing and Easement Limits (Erosion and Sediment Control Requirement Number 2) Appropriate clearing limits, property lines, easement lines, and similar boundaries shall be determined prior to starting construction. Clearing, grubbing, grading and similar operations shall not begin until the appropriate limits are staked in the field. Once these stakes are set, care shall be taken that the stakes are not disturbed. D. Protection of Adjacent Properties (Erosion and Sediment Control Requirement Number 3) As required by the DOE Manual, no flows from exposed or disturbed soils are to leave the project site without first having been treated with some type of sediment trapping/filtering system or device. The proposed arrangement ofthese devices and systems is described above. The individual items are discussed in more detail in the section on Sediment Trapping above. 20 . . . I I . . . I . . I . . . I -. I I The protective measures shown on the site plan are designed to prevent sediment deposition on adjacent properties. To the extent that the various items are constructed as designed and other work on the site progresses as envisioned, sediment should not be deposited on neighboring properties. Last minute changes in other items of work on this project, responses to previously unknown site conditions, or unexpected weather may require that revisions to the sediment trapping provisions of this plan be made rapidly. To this end, the previous section on Sediment Trapping contains design criteria, comments, information about BMPs, and similar information that is intended to be used in rapidly responding to changing needs and changing site conditions. As soon as a previously unexpected threat to adjacent properties becomes apparent, sufficient measures shall be taken to either eliminate the source of the threat or to provide an adequate level of defense against the threat. The measures taken shall provide a level of defense against sediment deposition on adjacent properties at least as secure as those provided by the remainder of this plan. E. Timing and Stabilization of Sediment Trapping Measures (Erosion and Sediment Control Requirement Number 4) It is essential that the various sediment trapping systems and devices be constructed prior to exposing the upslope soils to the elements. Both the timing of construction of the measures and the stabilization of the slopes of the structural BMPs are mandatory parts of this plan. 1. Timing of Installation of BMPs In keeping with the goal of providing positive sediment trapping or removal for all runoff from exposed soils before the runoff leaves the project site, no soil shall be exposed, or grading operations performed, until all of the required BMPs in the drainage path below the area to be exposed have been completed. Clearing, grubbing, and grading operations necessary for the construction of the BMPs are excepted from this requirement. 2. Stabilization of slopes of structural BMPs It is critical that the slopes of ditches, berms, ponds, and similar structural items be stabilized. These slopes will not only shed as much silt as any other exposed slope, but their erosion could cause the failure of the structural BMP. This could easily result in the failure of the BMP to perform its task of forcing sediment deposition to occur in a controlled location. This would leave open the potential for erosive transport of soil from a much larger area than that originally exposed on the slope of the BMP. F. Cut and Fill Slopes (Erosion and Sediment Control Requirement Number 5) Newly created slopes shall be covered or otherwise protected as provided for elsewhere in this plan. 21 I I I I I I I I I I I I I I I I I I I The faces of newly created fill slopes shall be well compacted. Since it is often impossible for typical compaction equipment to adequately compact the outer one to three feet of a fill, it will be necessary for compaction equipment to be operated up and down the face of the slope after the fill is completed. Operating tracked equipment in this manner will provide a certain amount of slope roughness which is desirable in slowing the velocity of running water and in retaining seed and fertilizer. After cut or fill slopes are covered, they should be monitored to ensure that the covering is functioning as intended and that rills are not fonning under or through the covering. G. Controlling Off-Site Erosion (Erosion and Sediment Control Requirement Number 6) The BMPs specified by this plan are intended to prevent damage to downstream and/or adjoining properties. To the extent that construction of this project is perfonned as intended and all elements of this plan are implemented, there should be no off-site erosion. It is possible that extensive covering of slopes and similar practices could increase the volume of peak floods, especially if a stonn event greater than a two year event were to occur before the site were completely revegetated and the stonnwater infiltration/detention systems completed. The possibility of this occurring increases significantly if construction is delayed and exposed slopes must be covered through a winter rainy season instead of having been successfully revegetated. While this is not expected to occur, is possible that the vagaries of the construction trade will cause this to happen. If this does occur, downstream drainage channels shall be inspected before the end of the Fall planting season and an inventory made of areas where increased flows would reasonably be expected to cause erosion. Such areas shall then be protected in a manner consistent with the goals and guidelines included within this plan. Those BMPs noted above as being held in "ready reserve" on this project may be brought up to active status by their use in such off-site situations. H. Stabilization of Temporary Channels and Outlets (Erosion and Sediment Control Requirement Number 7) Channels, slopes, embankments, trenches, and similar areas of disturbed soil which are required for the implementation of this erosion control plan shall be subject to the same erosion control requirements as other portions of the project. In addition to the general protective requirements, specific annoring methods are included in the appropriate details. I. Underground Utility Construction (Erosion and Sediment Control Requirement Number 9) Underground utility construction shall proceed subject to the following criteria. A major source of potentially contaminated flows is from pumping or otherwise dewatering trenches. For this reason, flows discharged from pumping or other method of trench dewatering shall be closely monitored 22 I I I I I I I I I I I I I I I I I I I and, except where there is no visible turbidity, treated as described below in the Section titled "Dewatering Construction Sites." Where feasible, no more than 500 feet of trench shall be opened at one time. Where consistent with safety and space considerations, stockpiles of excavated soils shall be placed on the uphill side of the trench. Any such stockpiles shall be protected from erosion as provided for in this plan. Trenches shall be backfilled and revegetated as soon as reasonably possible , following placement of utilities. Wherever trenches run more or less straight up and down a slope, either the backfill shall be mounded over the trench or waterbars or similar BMPs shall be utilized as necessary to prevent the backfilled trench from becoming a water course. Simply covering the exposed soil may not prevent the trench from conveying waters. Where the upstream end of a pipe is subject to inundation, it shall be temporarily capped or plugged at the end of each day's work to prevent soil from being washed into the pipe. The underground utility locate service, 1-800-424-5555, shall be called a minimum of 48 hours (2 working days) prior to beginning any excavation and arrangements made to have all buried utilities marked. J. Construction Access Routes (Erosion and Sediment Control Requirement Number 10) It is expected that minor amounts of soil will be tracked onto paved roads, especially when unexpected circumstances such as rains and delays occur. To prevent this from becoming a nuisance or source of sedimentation, the roads shall be cleaned thoroughly at the end of each day if there is evidence of any . significant accumulation of soil. Sediment shall be removed from roads by shoveling or sweeping and be transported to a controlled sediment disposal area. Washing of the street shall be allowed only after sediment is removed in this manner. Wherever construction, delivery, and similar vehicles enter paved roads from this project, the following provisions shall be followed to minimize the transport of soil onto the paved road. During periods of dry weather (where the soil is too dry to adhere to the tires of construction vehicles) construction vehicles may access paved streets directly from the project site with monitoring and occasional sweeping of the paved street as necessary to prevent accumulations of soil. During periods of wet weather (where soil readily adheres to the tires of vehicles) the vehicles may access graveled roads directly from the project site as necessary, but shall not access paved roads without first having been routed over areas where existing grass or other vegetation remains or routed down a minimum of 150 feet of graveled road. Access routes over grass or other vegetation shall be changed occasionally to ensure that wheel ruts are not allowed to develop and that the vegetation is not unduly worn down. 23 I I I I I I I I I I I I I I I I I I i I K. Removal of Temporary BMPs (Erosion and Sediment Control Requirement Number 11) Temporary Erosion Control Facilities shall be promptly (within 60 days) removed, once their presence is no longer required. During their removal, any entrapped sediment shall be disposed of in suitable locations on the project site where they will not be subject to erosion. Disturbed areas left after the removal of sediments shall be promptly stabilized. As an alternate to the removal of entrapped sediments, they may be stabilized in place by the application of suitable BMPs such as sodding, mulching, seeding, etc. In no case shall sediments be left in a channel or where they would be washed into receiving waters by the next stonn. The role of the Erosion Control Facilities is to prevent sediments from entering waters, not to merely delay it until after construction is completed. Dewatering Construction Sites Requirement Number 12) Discharges from pumps used in dewatering trenches or other portions of a construction site shall be dispersed by one of the following methods: L. (Erosion and Sediment Control Directing flows onto existing heavily vegetated areas. If this is done, the flows shall be directed against objects such as old tires or stumps, capable of disrupting concentrated flows. Directing flows onto a pad constructed of clean, pit run gravel or washed drain rock or pea gravel. The pad shall be a minimum of 15 feet square and flows shall be directed into a circle of 6 - 8 inch diameter stones to assist in dispersing flows into sheet flows. Directing flows directly into a grassy swale or other sediment trapping BMP, constructed per this plan. In no case shall flows discharged from a pump be allowed to remain as a concentrated flow. Every effort shall be made to break the flows into sheet flows. In all cases, flows from dewatering shall be routed through a sediment trapping BMP before being released off of the site. M. Control of Pollutanta Other than Sediment (Erosion and Sediment Control Requirement Number 13) All potential pollutants other than sediments that may occur on the site during the construction process shall be handled and disposed of in a manner that does not cause contamination of stonnwater. 24 I I I I I I I I I I I I I I I I I I I 1. Control of'lbxic Substances No toxic or noxious substances shall be used, stored or disposed of on or off the project site in conjunction with the project except in full compliance with all applicable federal, state and local laws and regulations and the recommendations of the supplier of the substance. The product label or instructions for use and the Material Safety Data Sheets (MSDS) for such products shall be kept on the site until the product has been used up or removed from the site and properly disposed of. While not commonly thought of as a hazardous material, common fertilizer can be very damaging if allowed to enter receiving waters. Fertilizers shall only be used in accordance with the recommendations of the supplier and any concentrations such as dribbles or leaks shall be cleaned up. In the event of a spill or other unusual event involving toxic or hazardous materials, work in the vicinity shall be immediately stopped and the following agencies notified: Washington State Department of Ecology, (206) 459-6000 during normal business hours or (206) 753-2353 after hours. If the incident presents a threat to life, health, or property, the Fire and Police Departments shall be notified by dialing 911. 2. Petroleum Spills The following requirements are included to ensure compliance with Part 40 of CFR 112 in cases where SPCC Plans are required. They shall be followed on all projects. Storage of fuel for construction vehicles and fueling of construction vehicles shall be performed in accordance with the following requirements: a. Driver Training All employees assigned to operate fuel trucks will be properly trained in appropriate regulations and safety procedures. Training shall include proper inspection and use of tanks, hatches, valves, pumps, hoses and fuel delivery equipment. b. Fueling of Vehicles Fuel nozzles shall be locked when not attended and hoses shall be rewound or otherwise properly stored when not in use. Unattended fueling which relies on the proper operation of automatic shutoff nozzles shall not be permitted. 25 I I I I I I I I I I I I I I I I I I I c. Parking of Fuel Tankers Parking areas for fuel trucks shall be selected such that spills will not leave the area. Fuel trucks shall not be parked closer than 25 feet to a conveyance BMP such as a grassy swale or interceptor swale. When fuel trucks must be taken to other portions of the project to fuel equipment, they must be continuously attended or returned to the staging/storage area. Fuel trucks shall be locked with the wheels chocked when unattended and not in use. d. Containment of Spills Spills shall be immediately diked and every effort made to stop spillage. Each fuel truck shall carry a long handled shovel for use in containing spills. In the event of a spill, the U. S. Environmental Protection Agency, Seattle, Washington (206) 442-1263, shall be notified as soon as possible. If the magnitude of the spill is such that it presents an immediate threat to life, health, or property, it shall be promptly reported by dialing 911. N. Maintenance (Erosion and Sediment Control Requirement Number 14) This section constitutes the Operation and Maintenance Manual for the erosion and sediment control BMPs used during the construction phase of this project. Most of the various BMPs required to maintain water quality during the construction phase of this project are of a temporary nature. They are neither intended nor expected to remain in service for months at a time. The typical BMP often has a life expectancy of only 6 - 12 weeks unless time and effort are expended to bring it back to its original condition. Foul weather, rough use, overloading and similar conditions will reduce the life of these items. It is critical that all of the erosion and sediment control BMPs be maintained in their intended condition until they have served their purpose and are ready to be removed. The project foreman shall inspect the various parts of the system at least once daily during rainy weather. In addition, the foreman shall perform additional inspections during or immediately after significant rainfall. Any damaged or non-functioning components of the system shall be repaired before noon of the next day. In addition to verifying that the various BMPs are functioning as intended, the foreman shall check for formation of rills, deposits of silt and similar indications that the system is not functioning properly. If it is found that the system is not performing its role in preventing erosion and sedimentation, additional BMPs shall be provided as necessary. Specific maintenance instructions for the various erosion and sediment control BMPs are contained in the DOE Manual. 26 I I I I I I I I I I I I I I I I I I I O. Financial Responsibility Construction, operation, maintenance, replacement, and final removal of the. erosion and sedimentation control BMPs is an integral part of the construction of this project. When referenced as such by the construction contract or similar documents, this plan forms a part of the construction plans for this project. In such cases the erosion and sedimentation control work is covered under applicable financial instruments such as the contractor's and developer's bonds to the same extent as all other items of work shown in the construction plans. 27 I I File: SEAH01. WB2 Date: April 14, 2006 BASIN DATA PROJECT: Seahome Services, Inc., 247 Franks Lane I Pre development I Undetained 0.1148 (Ac) + 81. 0 6. (min) Detained 0.0000 100.0 6 Area: Cn: Tc: I Postdeveloprnent Basin Data I (Ac) Total 0.1148 (Ac) (min) Undetained Detained Area: 0.0000 (Ac) + 0.1148 (Ac) en: 100.0 98.0 Tc: 6 (min) 6 (min) Total 0.1148 (Ac) I RAINFALL I 24 hr rainfall depth I :2 yr storm: 25 yr storm: 100 yr storm: 2.80 (in) 5.00 (in) 5.70 (in) I PRBDEVELOPMENT RUNOFF I I :2 yr storm.: 25 yr storm: 100 yr storm: I POSTDEVELOPMENT RUNOFF I Peak Runoff From Undeveloped Portln (Undetained) ------------------ -----(Qpos1)----- 2 yr storm: 0.0000 (cfs) 25 yr storm: 0.0000 (efs) 100 yr storm: 0.0000 (efs) I I Peak Runoff From Entire Basin ------------------ -----(Qpos)------ 2 yr storm: 0.0799 (efs) 25 yr storm: 0.1454 (efs) 100 yr storm: 0.1661 (cfs) I I I Peak Basin Rainfall ------ (Qr) __n_n 0.1050 (cfs) 0.1875 (efs) 0.2138 (efs) Peak Pre-Devt Runoff ------(Qpre)----- 0.0307 (efs) 0.0895 (cfs) 0.1097 (efs) Peak Runoff From Developed Portln (Detained) _n__ (Qpos2) ----- 0.0799 (efs) 0.1454 (efs) 0.1661 (cfs) I I I I I I I I I I I I I I I I I I I ~ ~ ~ ~ o . . 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'0 ~ . o ~ ~ ~ o c o ~ ~ '0 . ~ '" 0> ~ . ~ I I PROJEeT: Seahorne Services, Inc. , 247 Franks Lane 25 yr storm (B) ------------------------------------------------------------- I Total Basin Area = 5001 sq ft = 0.1148 Ae Storm Duration = 24 hr Peak Rainfall Intensity 0.188 efs Total Rainfall Volume 2084 eu ft I Total, 24 hr rainfall 5.00 in Rainfall Data I Standard ses Type 1A ----------------------------------- 24 hr hyetograph (adj'd) Total Cumulative from King eo Drn Manual Basin Preeip precip ------------------------ Rainfall Depth Depth I Time % Cumulative Time P pr Pre (min) Precip % Precip (hrs) (cfs) (in) (in) ------- ------- -------- ------- ------- ------- ------- I 0 0.00 0.00 0.00 0.0000 0.0000 0.0000 10 0.40 0.40 0.17 0.0139 0.0200 0.0200 20 0.40 0.80 0.33 0.0139 0.0200 0.0400 I 30 0.40 1.20 0.50 0.0139 0.0200 0.0600 40 0.40 1.60 0.67 0.0139 0.0200 0.0800 50 0.40 2.00 0.83 0.0139 0.0200 0.1000 60 0.40 2.40 1.00 0.0139 0.0200 0.1200 I 70 0.40 2.80 1.17 0.0139 0.0200 0.1400 80 0.40 3.20 1. 33 0.0139 0.0200 0.1600 90 0.40 3.60 1.50 0.0139 0.0200 0.1800 I 100 0.40 4.00 1.67 0.0139 0.0200 0.2000 110 0.50 4.50 1.83 0.0174 0.0250 0.2250 120 0.50 5.00 2.00 0.0174 0.0250 0.2500 I 130 0.50 5.50 2.17 0.0174 0.0250 0.2750 140 0.50 6.00 2.33 0.0174 o . 0250 0.3000 150 0.50 6.50 2.50 0.0174 0.0250 0.3250 160 0.50 7.00 2.67 0.0174 0.0250 0.3500 I 170 0.60 7.60 2.83 0.0208 0.0300 0.3800 180 0.60 8.20 3.00 '0.0208 0.0300 0.4100 190 0.60 8.80 3.17 0.0208 0.0300 0.4400 I 200 0.60 9.40 3.33 0.0208 0.0300 0.4700 210 0.60 10.00 3.50 0.0208 0.0300 0.5000 220 0.60 10.60 3.67 0.0208 0.0300 0.5300 230 0.70 11.30 3.83 0.0243 0.0350 0.5650 I 240 0.70 12.00 4.00 0.0243 0.0350 0.6000 250 0.70 12.70 4.17 0.0243 0.0350 0.6350 260 0.70 13.40 4.33 0.0243 0.0350 0.6700 I 270 0.70' 14.10 4.50 0.0243 0.0350 0.7050 280 0.70 14.80 4.67 0.0243 0.0350 0.7400 290 0.82 15.62 4.83 0.0285 0.0410 0.7810 I 300 0.82 16.44 5.00 0.0285 0.0410 0.8220 310 0.82 17.26 5.17 0.0285 0.0410 0.8630 320 0.82 18.08 5.33 0.0285 0.0410 0.9040 330 0.82 18.90 5.50 0.0285 0.0410 0.9450 I 340 0.82 19.72 5.67 0.0285 0.0410 0.9860 350 0.95 20.67 5.83 0.0330 0.0475 1.0335 360 0.95 21. 62 6.00 0.0330 0.0475 1.0810 I 370 0.95 22.57 6.17 0.0330 0.0475 1.1285 380 0.95 23.52 6.33 0.0330 0.0475 1.1760 i I I I PROJEeT: Seahome Services, Inc. , 247 Franks Lane 25 yr storm (B) ------------------------------------------------------------- I Total Basin Area = 5001 sq ft = 0.1148 Ae Storm Duration = 24 hr Peak Rainfall Intensity = 0.188 efs Total Rainfall Volume 2084 eu ft I Total, 24 hr rainfall 5.00 in Rainfall Data I Standard SCS Type 1A ----------------------------------- 24 hr hyetograph (adj'd) Total Cumulative from King Co Om Manual Basin Precip precip I ------------------------ Rainfall Depth Depth Time % CUmulative Time P Pr Pre (min) Precip % Preeip (hrs) (cfs) (in) (in) ------- ------- -------- ------- ------- ------- ------- I 390 0.95 24.47 6.50 0.0330 0.0475 1.2235 400 0.95 25.42 6.67 0.0330 0.0475 1.2710 410 1. 33 26.75 6.83 0.0462 0.0665 1.3375 I 420 1.33 28.08 7.00 0.0462 0.0665 1.4040 430 1. 33 29.41 7.17 0.0462 0.0665 1.4705 440 1.80 31.21 7.33 0.0625 0.0900 1. 5605 450 1.80 33.01 7.50 0.0625 0.0900 1. 6505 I 460 3.40 36.41 7.67 0.1181 0.1700 1. 8205 470 5.40 41.81 7.83 0.1875 0.2700 2.0905 480 2.70 44.51 8.00 0.0938 0.1350 2.2255 I 490 1. 80 46.31 8.17 0.0625 0.0900 2.3155 500 1.34 47.65 8.33 0.0465 0.0670 2.3825 510 1.34 48.99 8.50 0.0465 0.0670 2.4495 I 520 1.34 50.33 8.67 0.0465 0.0670 2.5165 530 0.88 51. 21 8.83 0.0306 0.0440 2.5605 540 0.88 52.09 9.00 0.0306 0.0440 2.6045 550 0.88 52.97 9.17 0.0306 0.0440 2.6485 I 560 0.88 53.85 9.33 0.0306 0.0440 2.6925 570 0.88 54.73 9.50 0.0306 0.0440 2.7365 580 0.88 55.61 9.67 0.0306 0.0440 2.7805 I 590 0.88 56.49 9.83 0.0306 0.0440 2.8245 600 0.88 57.37 10.00 0.0306 0.0440 2.8685 610 0.88 58.25 10.17 0.0306 0.0440 2.9125 I 620 0.88 59.13 10.33 0.0306 0.0440 2.9565 630 0.88 60.01 10.50 0.0306 0.0440 3.0005 640 0.88 60.89 10.67 0.0306 0.0440 3.0445 650 0.72 61. 61 10.83 0.0250 0.0360 3.0805 I 660 0.72 62.33 11.00 0.0250 0.0360 3.1165 670 0.72 63.05 11.17 0.0250 0.0360 3.1525 680 0.72 63.77 11. 33 0.0250 0.0360 3.1885 I 690 0.72 64.49 11. 50 0.0250 0.0360 3.2245 700 0.72 65.21 11. 67 0.0250 0.0360 3.2605 710 0.72 65.93 11.83 0.0250 0.0360 3.2965 720 0.72 66.65 12.00 0.0250 0.0360 3.3325 I 730 0.72 67.37 12.17 0.0250 0.0360 3.3685 740 0.72 68.09 12.33 0.0250 0.0360 3.4045 750 0.72 68.81 12.50 0.0250 0.0360 3.4405 I 760 0.72 69.53 12.67 0.0250 0.0360 3.4765 770 0.57 70.10 12.83 0.0198 0.0285 3.5050 I I I PROJEeT: Seahome Services, Inc., 247 Franks Lane 25 yr storm (8) ------------------------------------------------------------- Total Basin Area = 5001 sq ft = Storm Duration = Peak Rainfall Intensity Total Rainfall Volume Total, 24 hr rainfall I I I Standard SCS Type 1A 24 hr hyetograph (adj'd) from King eo Drn Manual I Time (min) 0.1148 Ae 24 hr 0.188 efs 2084 eu ft 5.00 in Rainfall Data ----------------------------------- % eumulative Preeip % Preeip Time (hrs) Total Basin Rainfall P (efs) Cumulative Precip precip Depth Depth pr Pre (in) (in) ------- ------- -------- ------- ------- ------- ------- I 780 790 800 810 820 830 840 850 860 870 880 890 900 910 920 930 940 950 960 970 980 990 1000 1010 1020 1030 1040 1050 1060 1070 1080 1090 1100 1110 1120 1130 1140 1150 1160 I I I I I I I I I I I I 0.57 0.57 0.57 0.57 0.57 0.57 0.57 0.57 0.57 0.57 0.57 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.43 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 70.67 71.24 71.81 72 .38 72.95 73.52 74.09 74.66 75.23 75.80 76.37 76.87 77 .37 77.87 78.37 78.87 79.37 79.87 80.37 80.87 81.37 81. 87 82.37 82.80 83.20 83.60 84.00 84.40 84.80 85.20 85.60 86.00 86.40 86.80 87.20 87.60 88.00 88.40 88.80 13.00 13.17 13 .33 13 .50 13.67 13.83 14.00 14.17 14.33 14.50 14.67 14.83 15.00 15.17 15.33 15.50 15.67 15.83 16.00 16.17 16.33 16.50 16.67 16.83 17.00 17.17 17.33 17.50 17.67 17.83 18.00 18.17 18.33 18.50 18.67 18.83 19.00 19.17 19.33 0.0198 0.0198 0.0198 0.0198 0.0198 0.0198 0.0198 0.0198 0.0198 0.0198 0.0198 0.0174 0.0174 0.0174 0.0174 0.0174 0.0174 0.0174 0.0174 0.0174 0.0174 0.0174 0.0174 0.0149 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0285 0.0285 0.0285 0.0285 0.0285 0.0285 0.0285 0.0285 0.0285 0.0285 0.0285 0.0250 0.0250 0.0250 0.0250 0.0250 0.0250 0.0250 0.0250 0.0250 0.0250 0.0250 0.0250 0.0215 0.0200 0.0200 0.0200 0.0200 o . 0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 3.5335 3.5620 3.5905 3.6190 3.6475 3.6760 3 . 7045 3.7330 3.7615 3.7900 3.8185 3.8435 3.8685 3.8935 3.9185 3.9435 3.9685 3.9935 4.0185 4.0435 4.0685 4.0935 4.1185 4.1400 4.1600 4.1800 4.2000 4.2200 4.2400 4.2600 4.2800 4.3000 4.3200 4.3400 4.3600 4.3800 4.4000 4.4200 4.4400 I I PROJEeT: Seahorne Services, Inc. , 247 Franks Lane 25 yr storm (B) ------------------------------------------------------------- Total Basin Area = 5001 sq ft = 0.1148 Ae I Storm Duration = 24 hr Peak Rainfall Intensity 0.188 efs Total Rainfall Volume 2084 eu ft I Total, 24 hr rainfall 5.00 in Rainfall Data I Standard ses Type 1A ----------------------------------- 24 hr hyetograph (adj'd) Total Cumulative from King Co Drn Manual Basin Precip Precip ------------------------ Rainfall Depth Depth I Time % Cumulative Time P Pr Pre (min) Precip % Preeip (hrs) (efs) (in) (in) ------- ------- -------- ------- ------- ------- ------- I 1170 0.40 89.20 19.50 0.0139 0.0200 4.4600 1180 0.40 89.60 19.67 0.0139 0.0200 4.4800 1190 0.40 90.00 19.83 0.0139 0.0200 4.5000 1200 0.40 90.40 20.00 0.0139 0.0200 4.5200 I 1210 0.40 90.80 20.17 0.0139 0.0200 4.5400 1220 0.40 91.20 20.33 0.0139 0.0200 4.5600 1230 0.40 91. 60 20.50 0.0139 0.0200 4.5800 I 1240 0.40 92.00 20.67 0.0139 0.0200 4.6000 1250 0.40 92 .40 20.83 0.0139 o . 0200 4.6200 1260 0.40 92.80 21. 00 0.0139 0.0200 4.6400 I 1270 0.40 93.20 21.17 0.0139 0.0200 4.6600 1280 0.40 93.60 21. 33 0.0139 0.0200 4.6800 1290 0.40 94.00 21. 50 0.0139 0.0200 4.7000 1300 0.40 94.40 21. 67 0.0139 0.0200 4.7200 I 1310 0.40 94.80 21. 83 o . 0139 0.0200 4.7400 1320 0.40 95.20 22.00 0.013 9 0.0200 4.7600 1330 0.40 95.60 22.17 0.0139 0.0200 4.7800 I 1340 0.40 96.00 22.33 0.0139 0.0200 4.8000 1350 0.40 96.40 22.50 0.0139 0.0200 4.8200 1360 0.40 96.80 22.67 0.0139 0.0200 4.8400 I 1370 0.40 97.20 22.83 0.0139 0.0200 4.8600 1380 0.40 97.60 23.00 0.0139 0.0200 4.8800 1390 0.40 98.00 23.17 0.0139 0.0200 4.9000 1400 0.40 98.40 23.33 0.0139 0.0200 4.9200 I 1410 0.40 98.80 23.50 0.0139 0.0200 4.9400 1420 0.40 99.20 23.67 0.0139 0.0200 4.9600 1430 0.40 99.60 23.83 0.0139 0.0200 4.9800 I 1440 0.40 100.00 24.00 0.0139 0.0200 5.0000 1450 0.00 100.00 24.17 0.0000 0.0000 5.0000 1460 0.00 100.00 24.33 0.0000 0.0000 5.0000 I 1470 0.00 100.00 24.50 0.0000 0.0000 5.0000 1480 0.00 100.00 24.67 0.0000 0.0000 5.0000 1490 0.00 100.00 24.83 0.0000 0.0000 5.0000 1500 0.00 100.00 25.00 0.0000 0.0000 5.0000 I ------- ------- 100.00 5.0000 I I I PROJECT : Seahorne Services. Inc. , 2.7 Franks Lane I Generation of Postdevelopment Runoff Hydrograph - Santa Barbara Urban Hydrograph Method 25 yr storm (A) Qpeak _ 0.1454 cf. Vtotal - 1985 cu ft I Pervious Portion of Basin Impervious Portion of Basin ------------------------------------------- ------------------------------------------- Pervious Area _ o 'q ft Impervious Area 5000.688 .q ft 0.0000 Ac 0.1148 Ac I Runoff CUrve Number, Cn_ 100 Runof f CUrve Number, Cn_ 98.0 Time of Coneentrat'n, Tc _ 6 min Time of Concentrat'n, Tc - 6 min Pot'l Max Nat'l Det'n, S _ 0.0000 in Pot'l Max Nat'l D@t'n, S _ 0.2041 in Routing Coefficient. w _ 0.4545 Routing Coefficient. w _ 0.4545 I ------------------------------------------- ------------------------------------------- CUmulative CUmulative CUmulative Ins tan- Instan- CUmulative Instan- Instan- Excess Excess taneous taneous Routed Excess Excess taneoue taneous Routed Total Precip Precip Runoff Runof f Runoff Precip precip Runoff Runoff Runoff Runoff I Time R Rc Oi Vc Or R Rc Oi Vc Or 0 (hrs) (in) (in) (cfs) (eu ft) (efs) (in) (in) (ds) leu ft) (cfs) (cfs) [o.ooJ 0.0000 0.0000 0.0000 0 0.0000 0.0000 0.0000 0.0000 0 0.0000 0.0000 [0.17J 0.0200 0.0200 0.0000 0 0.0000 0.0000 0.0000 0.0000 0 0.0000 0.0000 I [0.33J 0.0200 0.0400 0.0000 0 0.0000 0.0000 0.0000 0.0000 0 0.0000 0.0000 [0.50J 0.0200 0.0600 0.0000 0 0.0000 0.0016 0.0016 0.0011 1 0.0005 0.0005 CO.67} 0.0200 0.0800 0.0000 0 0.0000 0.0047 0.0063 0.0032 3 0.0020 0.0020 [0.831 0.0200 0.1000 0.0000 0 0.0000 0.0070 0.0133 0.0049 6 0.0039 0.0039 I [1.00J 0.0200 0.1200 0.0000 0 0.0000 0.0088 0.0221 0.0061 9 0.0053 0.0053 (1.17] 0.0200 0.1400 0.0000 0 0.0000 0.0103 0.0324 0.0072 14 0.0065 0.0065 [1.33] 0.0200 0.1600 0.0000 0 0.0000 0.0115 0.0439 0.0080 18 0.0075 0.0075 (1.50) 0.0200 0.1800 0.0000 0 0.0000 0.0125 0.0564 0.0087 2. 0.0083 0.0083 C1.67] 0.0200 0.2000 0.0000 0 0.0000 0.0133 0.0698 0.0093 29 0.0089 0.0089 I [1.83) 0.0250 0.2250 0.0000 0 0.0000 0.0176 0.0874 0.0122 36 0.0106 0.0106 [2.00] 0.0250 0.2500 0.0000 0 0.0000 0.0185 0.1059 0.0129 .. 0.0124 0.0124 [2.17] 0.0250 0.2750 0.0000 0 0.0000 0.0193 0.1251 0.0134 52 0.0130 0.0130 [2.33] 0.0250 0.3000 0.0000 0 0.0000 0.0199 0.1450 0.0138 60 0.0135 0.0135 (2.50J 0.0250 0.3250 0.0000 0 0.0000 0.0204 0.1654 0.0142 69 0.0139 0.0139 I [2.67] 0.0250 0.3500 0.0000 0 0.0000 0.0208 0.1862 0.0145 78 0.0143 0.0143 [2.83) 0.0300 0.3800 0.0000 0 0.0000 0.0255 0.2118 0.0177 88 0.0159 0.0159 (3.00] 0.0300 0.4100 0.0000 0 0.0000 0.0260 0.2378 0.0180 99 0.0177 0.0177 [3.17] 0.0300 0.4400 0.0000 0 0.0000 0.0264 0.2641 0.0183 110 0.0181 0.0181 [3.33J 0.0300 0.4700 0.0000 0 0.0000 0.0267 0.2909 0.0186 121 0.0184 0.0184 I [3.S0J 0.0300 0.5000 0.0000 0 0.0000 0.0270 0.3179 0.0188 132 0.0186 0.0186 [3.67] 0.0300 0.5300 0.0000 0 0.0000 0.0273 0.3452 0.0189 H. 0.0188 0.0188 (3.83] 0.0350 0.5650 0.0000 0 0.0000 0.0321 0.3773 0.0223 157 0.0205 0.0205 [4.00J 0.0350 0.6000 0.0000 0 0.0000 0.0324 0.4097 0.0225 171 0.0222 0.0222 I [4.17) 0.0350 0.6350 0.0000 0 0.0000 0.0326 0.4423 0.0226 18. 0.0225 0.0225 [4.33J 0.0350 0.6700 0.0000 0 0.0000 0.0328 0.4751 0.0228 198 0.0227 0.0227 [4.50] 0.0350 0.7050 0.0000 0 0.0000 0.0330 0.5081 0.0229 212 0.0228 0.0228 (4.67] 0.0350 0.7400 0.0000 0 0.0000 0.0331 0.5412 0.0230 226 0.0230 0.0230 [4.83] 0.0410 0.7810 0.0000 0 0.0000 0.0390 0.5802 0.0271 2.2 0.0249 0.0249 I [5.00) 0.0410 0.8220 0.0000 0 0.0000 0.0392 0.6194 0.0272 258 0.0269 0.0269 (5.17] 0.0410 0.8630 0.0000 0 0.0000 0.0393 0.6587 0.0273 27. 0.0272 0.0272 (5.33) 0.0410 0.9040 0.0000 0 0.0000 0.0394 0.6981 0.0274 291 0.0273 0.0273 [5.50] 0.0410 0.9450 0.0000 0 0.0000 0.0396 0.7377 0.0275 307 0.0274 0.0274 [5.67] 0.0410 0.9860 0.0000 0 0.0000 0.0397 0.7773 0.0275 32. 0.0275 0.0275 I (5.83J 0.0475 1.0335 0.0000 0 0.0000 0.0461 0.8234 0.0320 343 0.0296 0.0296 [6.00] 0.0475 1.0810 0.0000 0 0.0000 0.0462 0.8696 0.0321 362 0.0318 0.0318 [6.17J 0.0475 1.1285 0.0000 0 0.0000 0.0463 0.9158 0.0321 382 0.0321 0.0321 {6.33] 0.0475 1.1760 0.0000 0 0.0000 0.0464 0.9622 0.0322 .01 0.0322 0.0322 I [6.50J 0.0475 1.2235 0.0000 0 0.0000 0.0464 1.0086 0.0323 420 0.0322 0.0322 (6.67J 0.0475 1.2710 0.0000 0 0.0000 0.0465 1.0551 0.0323 440 0.0323 0.0323 [6.83] 0.0665 1. 3375 0.0000 0 0.0000 0.0652 1.1204 0.0453 '67 0.0382 0.0382 [7.00] 0.0665 1.4040 0.0000 0 0.0000 0.0653 1.1857 0.0454 49' 0.0447 0.0447 [7.17] 0.0665 1.4705 0.0000 0 0.0000 0.0654 1.2511 0.0454 521 0.0453 0.0453 I (7.33] 0.0900 1.5605 0.0000 0 0.0000 0.0887 1.3398 0.0616 558 0.0528 0.0528 (7.50J 0.0900 1. 6505 0.0000 0 0.0000 0.0888 1.4286 0.0617 595 0.0608 0.0608 [7.67] 0.1700 1.8205 0.0000 0 0.0000 0.1680 1.5966 0.1167 665 0.0866 0.0866 [7.83J 0.2700 2.0905 0.0000 0 0.0000 0.2675 1.8641 0.1858 777 0.1454 0.1454 l8.00] 0.1350 2.2255 0.0000 0 0.0000 0.1340 1.9980 0.0930 833 0.1399 0.1399 I [8.17] 0.0900 2.3155 0.0000 0 0.0000 0.0894 2.0874 0.0621 870 0.0832 0.0832 [8.33J 0.0670 2.3825 0.0000 0 0.0000 0.0666 2.1540 0.0462 898 0.0568 0.0568 (8.50] 0.0670 2.4495 0.0000 0 0.0000 0.0666 2.2205 0.0462 925 0.0472 0.0472 [8.67) 0.0670 2.5165 0.0000 0 0.0000 0.0666 2.2871 0.0463 953 0.0463 0.0463 {8.83] 0.0440 2.5605 0.0000 0 0.0000 0.0437 2.3309 0.0304 '71 0.0390 0.0390 I (9.00] 0.0440 2.6045 0.0000 0 0.0000 0.0438 2.3747 0.0304 990 0.0312 0.0312 [9.17J 0.0440 2.6485 0.0000 0 0.0000 0.0438 2.4184 0.0304 1008 0.0305 0.0305 [9.33] 0.0440 2.6925 0.0000 0 0.0000 0.0438 2.4622 0.0304 1026 0.0304 0.0304 . , I I PROJECT : Seahorne Services, Inc. , 247 Franks Lane I Generation of Postdevelopment Runoff Hydrograph - Santa Barbara Urban Hydrograph Method 25 yr storm (Al Qpeak _ 0.1454 cfs Vtotal - 1985 cu ft I Pervious Portion of Basin Impervious Portion of Basin ------------------------------------------- --------~---------------------------------- Pervious Area _ o sq ft Impervious Area _ 5000.688 sq ft 0.0000 Ac 0.1148 Ac I Runoff CUrve Number, Cn_ 100 Runof f CUrve Number, Cn_ 98.0 Time of Concentrat'n, Tc . 6 min Time of Concentrat'n, Tc _ 6 min Pot'l Max Nat'l Det'n, S 0.0000 in Pot'l Max Nat'l Det'n, S _ 0.2041 in Routing Coefficient, w _ 0.4545 Routing Coefficient, w _ 0.4545 ------------------------------------------- ------------------------------------------- I CUmulative CUmulative CUmulative Instan- Instan- Cumulative Instan- Instan- Excess Excess taneous taneous Routed Excess Excess taneous taneou8 Routed Total Precip Precip Runoff Runoff Runoff Precip Precip Runoff Runoff Runoff Runoff I Time R Rc Qi Vc Qr R Rc Qi Vc Qr Q (hrs) (in) (in) (cts) (eu tt) (ets) (in) (in) (cfs) (eu ft) (cfs) (ds) [9.50J 0.0440 2.7365 0.0000 0 0.0000 0.0438 2.5060 0.0304 1044 0.0304 0.0304 [9.67] 0.0440 2.7805 0.0000 0 0.0000 0.0438 2.5498 0.0304 1063 0.0304 0.0304 I [9.83] 0.0440 2.8245 0.0000 0 0.0000 0.0438 2.5935 0.0304 1081 0.0304 0.0304 (10.00J 0.0440 2.8685 0.0000 0 0.0000 0.0438 2.6373 0.0304 1099 0.0304 0.0304 [10.17] 0.0440 2.9125 0.0000 0 0.0000 0.0438 2.6811 0.0304 1117 0.0304 0.0304 [10.33) 0.0440 2.9565 0.0000 0 0.0000 0.0438 2.7250 0.0304 1136 0.0304 0.0304 I Uo .50] 0.0440 3.0005 0.0000 0 0.0000 0.0438 2.7688 0.0304 1154 0.0304 0.0304 [10.67J 0.0440 3.0445 0.0000 0 0.0000 0.0438 2.8126 0.0304 1172 0.0304 0.0304 (10.83J 0.0360 3.0805 0.0000 0 0.0000 0.0359 2.8484 0.0249 1187 0.0279 0.0279 [11.001 0.0360 3.1165 0.0000 0 0.0000 0.0359 2.8843 0.0249 1202 0.0252 0.0252 [11.17J 0.0360 3.1525 0.0000 0 0.0000 0.0359 2.9202 0.0249 1217 0.0249 0.0249 I (11.33] 0.0360 3.1885 0.0000 0 0.0000 0.0359 2.9560 0.0249 1232 0.0249 0.0249 [11.50J 0.0360 3.2245 0.0000 0 0.0000 0.0359 2.9919 0.0249 1247 0.0249 0.0249 [l1.67J 0.0360 3.2605 0.0000 0 0.0000 0.0359 3.0278 0.0249 1262 0.0249 0.0249 [11. 83J 0.0360 3.2965 0.0000 0 0.0000 0.0359 3.0636 0.0249 1277 0.0249 0.0249 [12.00J 0.0360 3.3325 0.0000 0 0.0000 0.0359 3.0995 0.0249 1292 0.0249 0.0249 I [12.17] 0.0360 3.3685 0.0000 0 0.0000 0.0359 3.1354 0.0249 1307 0.0249 0.0249 [12.33] 0.0360 3.4045 0.0000 0 0.0000 0.0359 3.1713 0.0249 1322 0.0249 0.0249 [12.50J 0.0360 3.4405 0.0000 0 0.0000 0.0359 3.2072 0.0249 1337 0.0249 0.0249 [12.67J 0.0360 3.4765 0.0000 0 0.0000 0.0359 3.2430 0.0249 1351 0.0249 0.0249 [12.83] 0.0285 3.5050 0.0000 0 0.0000 0.0284 3.2715 0.0197 1363 0.0226 0.0226 I [13.00] 0.0285 3.5335 0.0000 0 0.0000 0.0284 3.2999 0.0197 1375 0.0200 0.0200 (13.17J 0.0285 3.5620 0.0000 0 0.0000 0.0284 3.3283 0.0197 1387 0.0198 0.0198 [13 .33J 0.0285 3.5905 0.0000 0 0.0000 0.0284 3.3567 0.0197 1399 0.0197 0.0197 [13.50] 0.0285 3.6190 0.0000 0 0.0000 0.0284 3.3851 0.0197 1411 0.0197 0.0197 I [13.67] 0.0285 3.6475 0.0000 0 0.0000 0.0284 3.4135 0.0197 1423 0.0197 0.0197 {13.83J 0.0285 3.6760 0.0000 0 0.0000 0.0284 3.4420 0.0197 1434 0.0197 0.0197 (14 .00] 0.0285 3.7045 0.0000 0 0.0000 0.0284 3.4704 0.0197 1446 0.0197 0.0197 [14.17J 0.0285 3.7330 0.0000 0 0.0000 0.0284 3.4988 0.0197 1458 0.0197 0.0197 [14.33] 0.0285 3.7615 0.0000 0 0.0000 0.0284 3.5272 0.0197 1470 0.0197 0.0197 I (14.50J 0.0285 3.7900 0.0000 0 0.0000 0.0284 3.5556 0.0197 1482 0.0197 0.0197 [14 .67J 0.0285 3.8185 0.0000 0 0.0000 0.0284 3.5841 0.0197 1494 0.0197 0.0197 [14.83] 0.0250 3.8435 0.0000 0 0.0000 0.0249 3.6090 0.0173 1504 0.0186 0.0186 U5.00) 0.0250 3.8685 0.0000 0 0.0000 0.0249 3.6339 0.0173 1514 0.0174 0.0174 [15.17] 0.0250 3.8935 0.0000 0 0.0000 0.0249 3.6589 0.0173 1525 0.0173 0.0173 I [15.33] 0.0250 3.9185 0.0000 0 0.0000 0.0249 3.6838 0.0173 1535 0.0173 0.0173 [15.501 0.0250 3.9435 0.0000 0 0.0000 0.0249 3.7087 0.0173 1546 0.0173 0.0173 [15.67J 0.0250 3.9685 0.0000 0 0.0000 0.0249 3.7337 0.0173 1556 0.0173 0.0173 US.83] 0.0250 3.9935 0.0000 0 0.0000 0.0249 3.7586 0.0173 1566 0.0173 0.0173 I [16.001 0.0250 4.0185 0.0000 0 0.0000 0.0249 3.7836 0.0173 1577 0.0173 0.0173 (16.17) 0.0250 4.0435 0.0000 0 0.0000 0.0249 3.8085 0.0173 1587 0.0173 0.0173 (16.33) 0.0250 4.0685 0.0000 0 0.0000 0.0249 3.8334 0.0173 1597 0.0173 0.0173 [16.50) 0.0250 4.0935 0.0000 0 0.0000 0.0249 3.8584 0.0173 1608 0.0173 0.0173 [16.67] 0.0250 4.1185 0.0000 0 0.0000 0.0249 3.8833 0.0173 1618 0.0173 0.0173 I {16.83] 0.0215 4.1400 0.0000 0 0.0000 0.0215 3.9048 0.0149 1627 0.0162 0.0162 [17.00] 0.0200 4.1600 0.0000 0 0.0000 0.0200 3.9247 0.0139 1636 0.0145 0.0145 [17.17J 0.0200 4.1800 0.0000 0 0.0000 0.0200 3.9447 0.0139 1644 0.0139 0.0139 [17.33] 0.0200 4.2000 0.0000 0 0.0000 0.0200 3.9646 0.0139 1652 0.0139 0.0139 (17.50] 0.0200 4.2200 0.0000 0 0.0000 0.0200 3.9846 0.0139 1660 0.0139 0.0139 I [17.67J 0.0200 4.2400 0.0000 0 0.0000 0.0200 4.0046 0.0139 1669 0.0139 0.0139 [17.83J 0.0200 4.2600 0.0000 0 0.0000 0.0200 4.0245 0.0139 1677 0.0139 0.0139 [18.00] 0.0200 4.2800 0.0000 0 0.0000 0.0200 4.0445 0.0139 1685 0.0139 0.0139 (18.17] 0.0200 4.3000 0.0000 0 0.0000 0.0200 4.0644 0.0139 1694 0.0139 0.0139 [18.33J 0.0200 4.3200 0.0000 0 0.0000 0.0200 4.0844 0.0139 1702 0.0139 0.0139 I [18.50J 0.0200 4.3400 0.0000 0 0.0000 0.0200 4.1044 0.0139 1710 0.0139 0.0139 [18.67] 0.0200 4.3600 0.0000 0 0.0000 0.0200 4.1243 0.0139 1719 0.0139 0.0139 (18.83] 0.0200 4.3800 0.0000 0 0.0000 0.0200 4.1443 0.0139 1727 0.0139 0.0139 I I I I I I I Time (hrs) I [19.00] [19.17] (19.33) [19.50] [19.67] (19.83] (20.00) [20.17) [20.33) [20.50) [20.67] (20.83) [21. 00) [21.17) (21.33] [21. 50] [21.67) [21.83) (22.00) (22.17] [22.33) [22.50) (22.67] (22.83] (23.00) [23.17) [23.33] [23.50) (23.67) [23.83] [24.00] [24.17] (24.33) [24.50) (24.67) [24.83] [25.00] I I I I I I I I I I I I PROJECT; Seaborne Services, Inc., 247 Franks Lane Generation of Postdeve1opment Runoff Hydrograph _ Santa Barbara Urban Hydrograph Method 25 yr storm (A) Pervious Portion of Basin ------------------------------------------- Pervious Area '"' Runoff Curve Number, en * Time of Concentrat'n, Tc .. Pot'l Max Nat'l Det'n. S . Routing Coefficient, W .. a sq ft O.OOOOAc 100 6 min 0.0000 in 0.4545 ------------------------------------------- Cumulative Excess Excess Precip Precip R Rc {in} (in) 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 5.0000 4.4000 4.4200 4.4400 4.4600 4.4800 4.5000 4.5200 4.5400 4.5600 4.5800 4.6000 4.6200 4.6400 4.6600 4.6800 4.7000 4.7200 4.7400 4.7600 4.7800 4.8000 4.8200 4.8400 4.8600 4.8800 4.9000 4.9200 4.9400 4.9600 4.9800 5.0000 5.0000 5.0000 5.0000 5.0000 5.0000 5.0000 CUmulative Instan- Instan- taneous taneous Runoff Runoff Qi Vc (cfs) (cu ft) 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Max _ Routed Runoff Or (cfs) o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 o.ooao 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Qpeak _ Vtotal .. 0.1454 cfs 1985 cu ft Impervious Portion of Basin ------------------------------------------- Impervious Area _ Runoff CUrve NUmber. en _ Time of Concentrat'n, Tc _ Pot'l Max Nat'l Det'n, S Routing Coefficient, w .. 5000.688 sq ft 0.1148 Ac 98.0 6 min 0.2041 in 0.4545 ------------------------------------------- CUmulative Excess Excess Precip Precip R Rc (in) (in) 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0200 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 4.7632 4.1642 4.1842 4.2041 4.2241 4.2441 4.2640 4.2840 4.3040 4.3239 4.3439 4.3638 4.3838 4.4038 4.4237 4.4437 4.4637 4.4836 4.5036 4.5236 4.5435 4.5635 4.5835 4.6034 4.6234 4.6434 4.6633 4.6833 4.7033 4.7232 4.7432 4.7632 4.7632 4.7632 4.7632 4.7632 4.7632 4.7632 CUmulative Instan- Instan- taneous taneou$ Runoff Runoff 01 Ve (cfs) (eu ft) 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 3.3082 1735 1744 1752 1760 1769 1777 1785 1794 1802 1810 1819 1827 1835 1843 1852 1860 1868 1877 1885 1893 1902 1910 1918 1927 1935 1943 1952 1960 1968 1977 1985 1985 1985 1985 1985 1985 1985 max _ Routed Runoff Or (cis) 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0076 0.0007 0.0001 0.0000 0.0000 0.0000 0.1454 Total Runoff o (cfs) 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0139 0.0076 0.0007 0.0001 0.0000 0.0000 0.0000 0.1454