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Home My WebLink AboutDrainage Reports - 08/02/2018 (2)'City of Ft. Collins A rov d Plans Approved By Date FINAL DRAINAGE REPORT Elizabeth Street Farms Fort Collins, Colorado Prepared for: High Plains Builders, LLC P.O. Box 2796 Gillette, Wyoming 82717 Phone: (367) 257-2352 Prepared by: Galloway & Company, Inc.. 5265 Ronald Reagan Blvd., Suite 210 Johnstown, Colorado 80534 Phone: (970) 800-3300 Contact: Herman Feissner, PE Original Preparation: November 2nd, 2016 Revised: July 12th, 2017 Revised: September 121h, 2017 Revised: December 27`h, 2017 Revised: March 16`h, 2018 G a' oway Planning. Architecture. Engineering. t Gaowa ' Planning. Architecture. Engineering. ,TABLE OF CONTENTS TABLE OF CONTENTS..........._ ......... ......................................... .......... ............ :...................... ........ ...... . ' I. CERTIFICATIONS ..................... ...................................................................................................... 2 II. GENERAL LOCATION AND DESCRIPTION ................ :................................................................. 3 ' III. DRAINAGE BASINS AND SUB-BASINS............................................................... :......................... 5 IV. DRAINAGE DESIGN CRITERIA.....................................................................................................5 V. DRAINAGE FACILITY DESIGN....................................................................................................10 VI. EROSION AND SEDIMENT CONTROL MEASURES...................................................................13 ' Vll. CONCLUSIONS............................................................................................................................14 Vill. REFERENCES..............................................................................................................................15 APPENDIX A - REFERENCE MATERIALS VICINITY MAP NRCS SOILS MAP FEMA FIRMETTE CITY OF FORT COLLINS FLOOD MAPPING APPENDIX B - HYDROLOGY CALCULATIONS EXISTING RUNOFF CALCULATIONS PROPOSED RUNOFF CALCULATIONS APPENDIX C - HYDRAULIC CALCULATIONS SWALE CAPACITY CALCULATIONS DETENTION POND SIZING APPENDIX D - DRAINAGE MAPS + WEST PLUM PUD MEMORANDUM + VARIANCE APPLICATION DRAINAGE MAPS WEST PLUM PUD MEMORANDUM VARIANCE APPLICATION . 1 u Gallowayre !. CERTIFICATIONS CERTIFICATION OF ENGINEER "I hereby certify that this report for the final drainage design of Elizabeth Street Farms was prepared by me (or under my direct supervision) In accordance with the provisions of the Fort Collins Stormwater Criteria Manual for the owners thereof.' Herman Feissner, PE Registered Professional Engineer State of Colorado No. 38066 For and on behalf of Galloway & Company, Inc. CERTIFICATION OF OWNER 'High Plains Builders, LLC hereby certifies that the drainage facilities for the Elizabeth Street Farms be constructed according to the design presented in this report. We understand that the City of Fort Collins does not and will not assume liability for drainage facilities designed and/or certified by our engineer. We also understand that the City of Fort Collins relies on the representation of others to establish that drainage facilities are designed and constructed In compliance with City of Fort Collins guidelines, standards, or specifications. Review by the City of Fort Collins can therefore in no way limit or diminish any liability, which we or any other party may have with respect to the design or construction of such facilities." lains Builders, LLC Attest: (Name of Responsible Party) E TI CRIQUI - NOTARY PUBLIC YOF STATE OF BELLOMMISSION EXPIRES APRIL B. 201', 3 Gaoway ' Planning. Architecture. Engineering. ' II. GENERAL LOCATION AND DESCRIPTION LOCATION ' Elizabeth Street Farms (hereafter referred to as "the site' or "project site") is located at 2620 West Elizabeth Street. The site is bounded on north by single-family residential development and Pear Street right-of-way (existing cul-de-sac); on the south by West Elizabeth Street; and ' on the east and west by single-family residential. More specifically, the site is Tract A of West Plum Street — a Planned Unit Development situate in the north half of Section 16, Township 7 ' north, Range 69 west of the 6` Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. Refer to Appendix A for a vicinity map. DESCRIPTION OF PROPERTY The project site consists of t2.56 acres. It is largely vacant and undeveloped. Previously the ' site was used for agriculture. An existing two-story brick house, which the developer plans to ' restore, is located in the southeast region of the site. An existing irrigation lateral, which is still in use, crosses the site from west to east. The existing grades average between 0.50% and ' 1.00%. Locally steeper grades exist along the irrigation lateral and around the existing house. The existing runoff flows from northwest to southeast. An existing swale along the north edge ' of West Elizabeth Street captures existing runoff and conveys it east. ' There are no major drainage ways passing through the project site. ' According to the USDA NRCS Web Soil Survey, 'Altvan-Satanta loams, 0 to 3 percent slopes' covers roughly one-third of the project site. The remaining two-thirds of the site are 'Altvan- Satanta loams, 3 to 9 percent slopes'. These soils are associated with Hydrologic Soil Group (HSG) '13'. HSG '13' soils have a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of ' water transmission. Refer to Appendix A for additional soils information. Hollingsworth Associates, Inc. conducted a subsurface study the project site. The results of the preliminary geotechnical investigation are summarized in Subsurface Study for Ten Lots West Elizabeth Subdivision Fort Collins, Colorado (Job No.: 16-469 1 Dated: October 12, 2016). The ' 3 Ga€oway Planning. Architecture. Engineering. ' subsurface conditions across the lots were quite. uniform, as indicated by exploratory borings B-1 through B-5, and consisted of 12 inches of topsoil, 2 to 11 feet of medium stiff to stiff ' sandy clay, which occasionally graded into clayey sand, and 2 feet to 5 feet of firm to medium hard, interlayered and integrated weathered claystone/sandstone overlaying hard to very hard claystone for the depth drilled, 21 feet. The site is situated east of the Pleasant Valley and Lake Canal. An operational west -to -east ' irrigation lateral flows across the project site. According to the ditch rider, Ed Wendel, five people currently receive water from the lateral. Elizabeth Street Farms will develop in a single phase as single-family residential. The project ' includes the development of eight (8) single-family lots, street improvements, wet and dry utility infrastructure and landscaping. A single point of access will be provided to the project site from ' Pear Street. 4 G a olway Planning. Architecture. Engineering. ' III. DRAINAGE BASINS AND SUB -BASINS MAJOR BASIN DESCRIPTION ' The project site is located in the Canal Importation master plan drainage basin. According to the City of Fort Collins website (www.fcgov.com), this basin "spans nearly five square miles in west - central Fort Collins. Three major irrigation canals traverse the basin from north to south and ' impact the drainage in the basin. The canals can intercept runoff traveling through the basin and transport it out of the basin, and they also spill runoff into the basin when their capacity is ' exceeded". SUB- BASIN DESCRIPTION The project site generally conforms to the input parameters of SWMM subbasih 9 in the Canal ' Importation drainage basin. SWMM subbasin 9 is 60%. impervious. It generally drains to Elizabeth Street and then east. The proposed site will be ±56% impervious. The runoff ' ultimately drains into the.Red Fox Meadows neighborhood natural area. ' The project site is shown on FEMA Map Numbers 08069C0960F and 08069C0978G (refer to Appendix A for FEMA Firmettes). Neither map shows the project impacted by an existing flood plain/floodway. Refer to Appendix A for a copy of each Firmette and a copy of the City of . ' Fort Collins flood map. 5 Gall oway Planning. Architecture. Engineering. ' IV. DRAINAGE DESIGN CRITERIA REGULATIONS The final drainage design presented herein was prepared in accordance with the Fort Collins ' Amendments to the Urban Drainage and Flood Control District Criteria Manual (i.e., Urban Drainage and Flood Control District Urban Storm Drainage Criteria -Manuals Volumes 1, 2 and ' 3 [Manual]). Together, the requirements are referred to as the Fort Collins Stormwater Criteria Manual [FCSCM]. t DIRECTLY CONNECTED IMPERVIOUS AREA (DCIA) ' The project site is encumbered by several constraints; therefore, we developed a strategy for implementing 'The Four -Step Process' for stormwater quality management to the Maximum Extent Practicable (MEP). Each step is listed below along with a brief narrative describing the implementation strategy. ' Step 1 - Employ runoff reduction practices ' The developed runoff from basins Al .through A4 flow through grass -lined swales before entering the on -site detention facility. The UDFCD defines a Grass Swale as "Densely ' vegetated drainage way with low-pitched side slopes that collects and slowly conveys runoff. The design of the longitudinal slope and cross-section size forces the flow to be slow and shallow, thereby facilitating sedimentation while limiting erosion." The proposed grass -lined ' swales will have longitudinal slopes of ±0.50% and are designed to convey 2-year storm event runoff in a slow (i.e., <1 ft/sec) and shallow manner (i.e., normal depth<1 foot). This design encourages settling and infiltration. ' Approximately 1.2 acres of new impervious area will be created by the project. Of this, ±0.88 acre (73 percent) will be treated by the vegetated swales. The impervious areas have been ' disconnected to the Maximum Extent Practicable. (MEP) Step 2 - Implement BMPs that provide a Water Quality Capture Volume (WQCV). ' The proposed BMPs do not provide WQCV because of site constraints. Refer to DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS for additional Information. ' 6 Gaoway Planning. Architecture. Engineering. Step 3 - Stabilize drainageways Planting within the vegetated swales will stabilize the drainage way and prevent erosion during storm events exceeding the 2-year recurrence level. Step 4 - Implement site specific and other source control BMPS Site specific considerations such as material storage and other site operations are addressed in the Stormwater Management Plan (SWMP). ,DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS Several constraints drove the WQ/LID and detention pond design presented here. • The outfall from the proposed on -site detention pond is the flowline of West Elizabeth Street, elevation ±5107.41. • The developer wants to keep the existing house; this constrains the grading design. • The closest storm drain system is located more than one-half mile east along Elizabeth Street. • The site is generally flat. The existing grades average 0.50% to 1.00%. Locally steeper grades exist around the structures and existing irrigation lateral. • The project site is bounded by existing development. • The existing soils are unsuitable for infiltrating stormwater runoff. The boring logs show clay underlain by claystone/sandstone and claystone. Considering the expansive nature of the subgrade soils, the subsurface study recommended that residences be founded on drilled piers (refer to Appendix A for these boring logs). Appendix D contains a Stormwater Alternative ComplianceNariance Application. This document references a short list of 'hardships' preventing the site from meeting the requirements presented in ORDINANCE NO. 007 13.1 Low Impact Development criteria. HYDROLOGICAL CRITERIA For urban catchments that are not complex and are generally 160 acres or less in size, it is acceptable that the design storm runoff be analyzed using the Rational Method. The Rational Method is often used when only the peak flow rate or total volume of runoff is needed (e.g., VA Gaoway ' Planning. Architecture. Engineering. ' storm sewer sizing or simple detention basin sizing). The Rational Method was used to estimate the peak flow at each design point. Routing calculations (i.e., time attenuation) that ' aggregate the basins draining to a specific design point are included in the Rational Method calculations in Appendix B. ' The Rational Method is based on the Rational Formula: Q=CiA ' Where: Q = the maximum rate of runoff, cfs ' C = a runoff coefficient that is the ratio between the runoff volume from an area and the average rate of rainfall depth over a given duration for that area ti = average intensity of rainfall in inches per hour for a duration equal to the Time of Concentration (Tc)' A = area, acres ' The one -hour rainfall Intensity -Duration -Frequency tables for use with the Rational Method of runoff analysis is provided in Appendix B. The 2-year and 100-year storm events serve as the basis for the drainage system design. The ' 2-year storm is considered the minor storm event. It has a fifty percent probability of exceedance during any given year. The 100-year storm is considered the major storm event. It has a one percent probability of exceedance during any given year. 1 The 2-year drainage system, at a minimum, must be designed to transport runoff from the 2- year recurrence interval storm event with minimal disruption to the urban environment. The 100-year drainage system, at a minimum, must be designed to convey runoff from the 100- year recurrence interval storm event to minimize life hazards and health, damage to structures, and interruption to traffic and services. 1 8 Gaoway Planning. Architecture. Engineering. HYDRAULIC CRITERIA Street Capacity Analysis The street section generally drains from the crown, across the travel lane and into grass -lined roadside swales. The proposed street section is bounded by a one -foot wide concrete ribbon along each side of the asphalt. Storm Drain and Swale Capacity Analysis The storm drain system is limited to short culverts and swales that convey runoff underneath driveways and along the internal streets. The hydraulic analysis was completed using Bentley FlowMaster. Refer to Appendix C for swale and culvert capacity calculations. M Ga€€oway ' Planning. Architecture. Engineering. ' V. DRAINAGE FACILITY DESIGN GENERAL CONCEPT This final design presents a system for collecting and conveying developed runoff from the ' proposed development at Elizabeth Street Farms to the on -site detention pond. ' The on -site developed runoff in each catchment begins as overland flow from the residential lot areas (i.e., roof area, concrete hardscape and landscaping). This runoff then flows from the ' lots to the Swale sections along the backs and fronts of the lots. These swales drain into on - site detention pond (i.e., basin A5). ' SPECIFIC DETAILS ' On -Site Detention Pond The proposed on -site detention pond was sized with the Modified FAA Method (refer to Appendix C). The site constraints limited the volume of the on -site detention pond to 9385 ft3 (0.22 ac-ft). The proposed release rate from the detention pond is 1.2 cfs. The pond will ' discharge to the flowline in West Elizabeth Street. This proposed release rate exceeds the calculated 2-year release rate of t0.6 cfs (combined ' release from basins EX4 and EX5). There does not appear to be any remaining areas that can develop in SWMM subbasin 9, except for this site, and the site is located at the far west end of ' the basin. Considering this, the proposed increase in release rate will have a negligible effect on the basin during the 100-year storm event. A Basins ' These basins comprise approximately 1.84 acres. The developed runoff from the roof areas will flow overland through landscaping and. into grass -lined swales along the private internal streets. Flow in the swales will drain into the on -site detention pond. ' Basin Al will flow into the on -site detention pond through two (2) - 8" HDPE culverts. We proposed medium duty flapgates at the downstream end to prevent ponded water in basin A5 from draining back into basin Al. 1 10 Gaoway B Basin This basin is comprised of private street improvements and portions of two lots. The developed runoff from the structures will be disconnected from the street section by landscaped area. The undetained developed runoff, Q2=0.40 cfs and Q1oo=2.4 cfs, will drain into Pear Street and then flow north ±235 If, in the existing roll over curb and gutter, to an existing concrete cross pan. The cross pan conveys local developed runoff from West Plum Street PUD basin 2 (±2.75 acres, Q2=3.09 cfs, Q100=8.97 cfs) to the east in an existing swale with a concrete pan and into an existing detention pond. View of existing swale looking east from Pear Street Refer to Appendix D and the memorandum dated February 12, 2018 for an analysis of the existing West Plum Street P.U.D. swale hydraulics. Per the memorandum, "The proposed increase in flow would result in a 0.1' increase in WSEL in the swale in a 100-yr event." The proposed flows should have a negligible impact on the existing drainage infrastructure in this area. We do recommend clearing vegetation from underneath the fence situated perpendicular to the swale and at the point the swale drains into the existing detention pond (see photograph below). 11 rtn� At yes •+' fr t JS�Z-�j . eT s e _ -� :.i e'. ♦;�! 'Fein 4 .t /!7b"ar_ l Existing swale looking west at existing detention pond Ga'oway OS1 Basin This basin includes future West Elizabeth Street right-of-way and existing West Elizabeth Street improvements. The runoff will continue to flow east along Elizabeth Street. 12 i Ganoway Planning. Architecture. Engineering. VI. EROSION AND SEDIMENT CONTROL MEASURES A General Permit for Stormwater Discharge Associated with Construction Activities issued by the Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division (WQCD), will be acquired for the site. A Stormwater Management Plan (SWMP) was prepared and is presented separately. It identifies the Best Management Practices (BMPs) which, when implemented, will meet the requirements of the General Permit. 0 13 Gaoway Planning. Architecture. Engineering. VII. CONCLUSIONS COMPLIANCE WITH STANDARDS The design presented in this final drainage report for Elizabeth Street Farms has been prepared in accordance with the design standards and guidelines presented in the Fort Collins Stormwater Criteria Manual. VARIANCES A Stormwater Alternative Compliance/Variance Application is included in Appendix D. The site seeks a variance from meeting the requirements presented in ORDINANCE NO. 007 13.1 Low Impact Development criteria. DRAINAGE CONCEPT The proposed Elizabeth -Street Farms storm drainage improvements should provide adequate protection for the developed site. The proposed drainage design for the site should not negatively impact the existing downstream storm drainage system. 14 Ga€oway Planning. Architecture. Engineering. VII. REFERENCES 1. Fort Collins Stormwater Criteria Manual (Addendum to the Urban Storm Drainage Criteria Manuals Volumes 1, 2 and 3), prepared by City of Fort Collins. 2. Urban Drainage and Flood Control District, Drainage Criteria Manual Volumes 1 and 2, prepared by Wright -McLaughlin Engineers, dated June 2001 (revised April 2008), and the Volume 3, prepared by Wright -McLaughlin Engineers, dated September 1992 and revised November 2010. 15 Ga€oway Planning, Architecture. Engineering. APPENDIX A REFERENCE MATERIAL Ga€oway Planning. Architecture. Engineering. VICINITY MAP 'Jim" �10 yell puelJanp':=__._� G a "-I,,-o w ay Planning. Architecture. Engineering. N RCS SOILS MAP n OL91604 09916" OS916" O09164b OE9T6" OZ916bb 01916VV 009T64b 06ST6" OSST6W OLS16bb iRAi68k M.E£ 1 eSOT (0 V M.9LL oSOT N O � N N � O [6 �a I R 0 n T Z J n N O (n Z d ) 0 o U) � 3 U N3 c Mo m Z �n m m x p n g aC O N o f O N 3 N d� m 4 3 y O ry O 0 t7i n 'A'.-. f g o o F ` d N z-iiiiz oc ZU M.EE160T GI' Ji 0 � � ■ 0 LL IL � O z w 0 -j IL � }\�; )[ \ \\\ /\w\ 0 )() [ a,E (D!¥ 2kk){� . \/ \)k\k ) {/ (k) k £f)\| §2 0)\, ƒr- 0D tf |] 2/@ )= 2) 24)J)) �2 3fM2« k» �# `) {§ &f®/� \f 2/ + �t \/\W §f # FLE(n £Ea<u z *' co ƒ k`\ ({ ƒ / %mE . > a /{[{ . / {§; \ \\\\ L jE _ �` E { 3§ r £o \ ) 7 o ` _\ ` o e z \ \ $ ] o■■ o( u ! . m k k > 4 k - ] _ |$ 0 $ w , 0 0 0 z 0< , ! 0 0 c : Q « = ! §! 2! I/■■ k ; 0 _ \ §k j0 zu ZAI Hydrologic Soil Group—Larimer County Area, Colorado 2620 West Elizabeth Street Hydrologic Soil Group Hydrologic Soil Group— Summary by Map Unit— Larimer County Area, Colorado (C0644) Map unit symbol Map unit name Rating Acres in AOI Percent of A01 3 Altvan-Satanta loams, 0 to 3 percent slopes B 0.8 31.6% 4 Altvan-Satanta loams, 3 to 9 percent slopes B 1.7 68.4% Totals for Area of Interest 2.6 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long -duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate,of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink -swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. I Rating Options Aggregation Method: Dominant Condition USDA Natural Resources Web Soil Survey 10/25/2016 'im Conservation Service National Cooperative Soil Survey Page 3 of 4 Hydrologic Soil Group—Larimer County Area, Colorado 2620 West Elizabeth Street Component Percent Cutoff.- None Specified Tie -break Rule: Higher USDA Natural Resources Web Soil Survey 10/25/2016 a Conservation Service National Cooperative Soil Survey Page 4 of 4 SUMMARY AND CONCLUSIONS 1. The subsurface conditions across the ten lots were quite uniform, as ' indicated by exploratory borings B-1 through B-5, and consisted of 12 inches of topsoil, 2 feet to I feet of medium stiff to stiff sandy ' clay, which occasionally graded into a clayey sand, and 2 feet to 5 feet of firm to medium hard, interlayered and intergraded weathered claystone/sandstone overlying hard to very hard claystone for the depth drilled, 21 feet. No free water was encountered at the time of drilling. When the borings were checked three days later, free water was measured at depth 19.4 feet in boring B-2 only. 2. The residences should be founded on straight -shaft drilled piers drilled into bedrock. Piers should be designed for an allowable end bearing pressure of 30,000 psf and a skin friction of 3,000 psf for the portion of the pier in bedrock. Piers should also be designed for a minimum dead load pressure of 15,000 psf based on pier end area only. Piers should ' penetrate at least 10 feet into bedrock and have a minimum length of 15 feet. ' 3. The ground floors should be structural floors above a well -ventilated crawlspace supported on grade beams and piers. ' 4. The pavement section for the private street should consist of 6 inches of high quality base course and 4 inches of asphalt surface or 6 inches of full -depth asphalt. 5. Other geotechnical recommendations are provided in the body of the. report. PURPOSE AND SCOPE OF WORK This report presents the results of a geotechnical engineering study of the planned ten lots of the West Elizabeth Subdivision and the private street to be constructed at 2620 West Elizabeth Street in Fort Collins, Colorado. This study was conducted for the purposes of evaluating the residential foundation conditions and street subgrade and to provide a geotechnical engineering basis for the foundation design for the residences and a pavement section for the private street. The study was conducted in general accordance with our proposal P16-117 to High Plains Builders, LLC dated July 25, 2016. a Not to Scale m� SSS / /1 -- /----.�--- --�' —'— ----- I i I I I I LOr@ I LOT ' IOTA LC'A i )81 SF i 134 TMA SF I i2e2 eF B n2 Sr l_ 1 I I I � 1 I , •�nn®wr Ivma ^IemneleVt __ .In 1 I I I LOT n I® exrsnNa i Larr ' lare Lo*� ' BF?208TNoun 7%F•I 6.eu sF I ' I AOarrrOfw M OF R.O.W. I I.W SF W. CLIZABe TIC AVE. I --"`- _' i I mlwrn.,c. �M • B-1 --Exploratory boring Base map provided by High Plains Builders, LLC 16-469 rr°"'NGSW. '"S°"A`es Gml¢hnLocations of Exploratory Borings Fig. 1 leal�Ti...nvl nnlemnl l'.nylnom 0 ! 5 ' 10 t a 15 ' 20 1 1 1 t 16-469 B-1 35/ 12 50/8 �0 G B-2 26/ 12 19/12 22/12 50/6 B-3 36/ 12 50/10 B-4 37/ 12 B-5 28/ 12 50/10 ,u 6 (krolwhniial/lim nunnirnbl ftgl.a Logs of Exploratory Borings 0 5 O 10 J. 15 20 Fig. 2 LL( END ® Topsoil. Clay (CL), sandy, occasionally grades to a clayey sand, medium stiff to stiff, calcareous, dark brown, moist to very moist. 8 Weathered claystone/sandstone, interlayered and intergraded, firm to medium hard, calcareous, brown, moist. rClaystone, hard to very hard, brown, moist. Drive sample, 2-inch I.D., California liner sample. Disturbed bulk sample taken by shovel. 35/12 Drive sample blow count. Indicates that 35 blows of a 140-pound hammer falling 30 inches were required to drive the California sampler 12 inches. 3 Depth to water level and number of days after drilling measurement was made. NOTES 1. The exploratory borings were drilled on September 28, 2016, with a 4-inch diameter continuous flight auger. 2. The exploratory borings were located by HA personnel based on the planned building areas. 3. Logs are drawn to depth. 4. The lines between materials shown in the borings represent the approximate boundaries between material types and the transitions may be gradual. 5. Water level readings shown on the logs were made at the time and under conditions indicated. Fluctuations in the water levels may occur with time. uoi.i,rvc SIVOR n i ,�cSMIA MS 16-469 ��,,,�,,,,,,.,,..o,,,� „� �:,,.,,,. I Legend and Notes of Exploratory Borings Fig. 3 F FEMA FIRMETTE n G a I 11 oway Planning. Architecture. Engineering. U. i° -�c`=E p ao m� N mNNn E u a o E W LL� W C To d LLI m0�1-0�c O Q Q O c m o 2 �p W� C N P QZ O O J t` Z U01 Nm S.8 dnmE-v Vyo IQI LL Q a po Am Q mWcoC O a W F o¢ g S i 0 n LL W uW EEcZQ m L W O fj G0'' `aW nW Z od O ° ?� Q d 5 = O C 3 of it�y0� E1-9 o Q L O r Q O `? ? S u ¢� O O N H W Z i _I U z O��°C" nao Ag °u O O w EE °a < '` `t° m m £ ii LL I4 V Q d VI O 5 ° Q o z o '� U r11 Koh' Cj o u F c O V m D Y N N N y n z E M S S OOOM MOH 61 aN I83AO h Cd �r Cr U+�o o � O, C � C . �� O G645 X u 00�7. r� 0 0 0 FA E g 8L60 13NVd SNIOf O a O w J J Q i F Z W uj � a co co x H (ow m -T— 4 ond LLJ SLLJ / of e 2 © � !f ( § ~ \! 2B § 3 \§ !f 2 ƒ | ) k / ) L \$ g / /# uj § § - |!s» CD \ �` E c LU § B§{)/) !_,® !.a« , �(§§// \ qVO ) . ;!!!! ._.. -.J,- §@§ ,O °a to No k'E)\ � / |;:: _� >� ,m,s+;», \ ; am> a e_d»a 311GOVY »,S SKY». MOBILE HOME PARK ROAD »m iS380-1 a CTco a ) \ \ \ \ - 133UIS@ 82 74 m ) ) ) \ E ( ) / § \ em 2NVds en E o 6 G la"01,01i o w ay Planning. Architecture. Engineering. CITY OF FORT COLLINS FLOOD MAPPING L UU U i1 -;• _ - J GI Im d mm � a o M2, Q LL lL 8� N Oa o W a $ O x s < �Wi. LL r C N d N K Ca L 0 Q LL U 4` W > j � m r T U U — C J 0 Z N N Aso U o m LL � N � y C n O m m C r 'O J O LL Ln p U)00 O T C T m m m U � v E= m Q o , U YJ U N n C m 0 m n o m U m o T � O N o m E m- o m v G T N m N m � E rn.y n rn m E r = n m n m N E 6 r O 'C E m r^ U) N O U m O �U O _ � LL W vl O N LL U?i �C N - � m L Ul I r m K a' 0 U ul N m U Q o p LLLL C) a 3 U Gaowa ' Planning. Architecture. Engineering. APPENDIX B 1 HYDROLOGY CALCULATIONS 1 1 1 1 1 . 1 1 1 - 1 f 1 . Ga.€oway -1 Planning. Architecture. Engineering. 1 1 1 1 1 EXISTING RUNOFF CALCULATIONS 1 1 1 1 _ 1 1 1 1 1 1 1 1 CO Z W U LL LL W 0 U LL LL 0 Z LW r_ N 0 a 2 0 V NISISISI� N O Co CO « Z u m W in 0 + u a u t a�U U 1- F- 7 D a a Z Z U O N O N O N m N N N O O O O O a D m m R L 4 0 0 M m O m O U V 0 cI 0 0 g U m o c c c o a � � e k o o � W � O V e D s q W o N 0 N o N m �' m a 3 O m m m n = O t0 N V G m o k m C � m � U Y L W 3 m i� v V W O O O N O m 0 0 0 0 0 i y0 5 O O O O O m C - � m 0 U N o r ry n a O O O O N Al O r c N Om0 w G i N X X X N W W W W W m qq O T T O E Z N m q Z rvO LL N KKK Z O LL U O Z w O Q U 0, ZO Q W N � F X ffi E L E o m N N N L a m N w N y p � c d c 0o.�� N d 0 T T m E z m m z�mm� O Y A G a u V z li U 0 M W K LL p y 2 w LU x y O LL U)O LL W = w Q z r. z Q F 0 0 y Y Q w K w f (up)1 F j (Shc) gioola Q> y� (U) yl6ua r (wpul) aZIS adl w O- (%) adol a (sjO) M 1=1 UBISa W No) mold laap W C U)(%) edOI (sp) W LL O z K (3wu!) 4 (Od) d Q (ulw) 01 (p) O O O O N P O O (Jtl/UI) womb' m m CO of N LL LL O z (.d) V N O O W O N � O O O O U (ulw) J-,k-z I O O O N M W K_ t 0 I'g000 goun8 N N N O O tV N tV O O (OV) eel N O 0 0 0 b o . (31 u15e wwwww luiod uE m Nsa w w w a m w w r w w r m 0 L a N_ w C C > O N N t0 ryCL m LL LL N S x S N O > ! m E z m m z�mmim m A Y oa`�',t Z a U U fn w M w j G (n w ¢ y O a NC LL w C x w O < a C' moo N Q F y Y Q W K w f (UIW)7 F (517J) /yla0la w (y) y76Ua F (sayaul) azlg ad1 W IL (%) adol IL (slo) m I.A u61sa (sIo) mold n )aa ww N (%) adol (W) tD LL LL 0 Z U4N!)I C(oV) V. (Ulw) a 000.- (lll/UI) 1 NNmnm N in N aim ai N N 66 LL LL N N N N Q = 00.00 F MAao l (UIW) a 6 N N N n N U w N wl 0 J'poo jjounb N N N p� IY N ('tl) m O m OO O' n N O � al ulse �yO wu]`3w 7u1od ufilse w w w e Xa w w F w w K N N w U N 11 0 U t C N O Q y D II L m 7n cc m W O N O x . w f /\ Gaoway Planning. Architecture. Engineering. PROPOSED RUNOFF CALCULATIONS Table RO-11 Rational Method Runoff Coefficients for Composite Analysis Character of Surface Runoff Coefficient Streets, Parking Lots, Drives: Asphalt 0.95 Concrete 0.95 Gravel 0.5 Roofs 0.95 Recycled Asphalt 0.8 Lawns, Sandy Soil: Flat <2% 0.1 Average 2 to 7% 0.15 Steep >7% 0.2 Lawns, Heavy Soil: Flat <2% 0.2 Average 2 to 7% 0.25 Steep >7% 0.35 Table RO-12 ' Rational Method Runoff Coefficients for Composite Analysis Storm Return Period Frequency Factor ears C 2 to 10 1.00 I to25 1.10 26 to 50 1.20 51 to 100 1.25 Note: The product of C times Cf cannot exceed the value of 1, in the cases where it does a value of 1 must be used 1 o co N N o r o U <O (O N N V (O W 0 0 0 0 0 o c a m Y q t J V 3 Y a u q Y N Nl M O O LL Y O O O G O G G 0 C h ' C � � Y w `o is co m m 0 w YO J U 0 q A 3 LL u N Jy O O O O N O o yY o 0 o O O C O q Y Q x y � C C u qG j� a N CJ N N N N O U OI Y Y Y 3 O r N V N N (O N N t0 n A m Y � � c u n L C r m � o U q m O O O O O O O N E q F C y A Q m Z. W q a ~ o c q m � 0 c Y d O W l�==2:� ! ! § �§a■n■e �|k| ON •®rj; „ # a alaaaaa � � |`!! aRM=pq.q |-<■■„ ; § ! RAINFALL INTENSITY -DURATION -FREQUENCY CURVE 10.00 9.00 8.00 9 0 7.00 m m c e 6.00 F i 5.00 w t- = 4.00 J J Q LL C 2.00 1.00 0.00 0.00 10.00 20.00 30.00 40.00 50.00 60.00 STORM DURATION (minutes) - 2-Year Storrs - - - 10-Year Storrs -100-Year Storrs 0 m G E 0 m m q ' m y W 0 a U ' M Lau LL M m2W 'L H O K a } O N cl ' W O S Q z 2 <Q F 0 O 1 f N 0— O O € ' y 0 O > u N d J � � N N y m m m � m Y y d m y a W v m m v m ogm m W_ $, 3 vv., o o reK o u d 2 2 a m g g c u O °c m n m m m C C._ o 2 m m a i i g c m noy 2 2 c 0 o a o m J J J J O K R W (uIW)I F (a4) MwIS w M ta6ua F- (sayoul)az[g adid W a (%) ado[ a (sp) MOIJ u6lsa y~j (SIO) mold mil uj C y (%)adol (sV) • 0 O K (OV)V. O (ww) o NO O N t 0 n N t 7 oodoo N 0 O N N N N N N N O N N N m 0 LL (oV)V' o 0 0 0 0 0 0 LL O j (unu) iea l-z 131 rui K U 0I'Uaoo gounN Iq m u vNi e W m LU 000co o a (OV) egivn e e a 0000c H d o p Mod u6lsa a F�NO w 0: r N N ISISI=I� EzCOM 0 � Y 2 m a� M W m O U C fA 2 w R (a it U) O a W O F Q 2 i O Q Q C O to O I— U) 0 0 6 — O > u N O J c N m G 0 0 N N W U m 8i S m 0 m m ri Y W W m°° m e m 0 0 o Z 0 o 0 m � c m 2 2 _ mp mo 2 b b c 1 Z 2 2 C C m Q 2 m m 2'N 0 ? c 0 0 0 0 w J J J J O K K W (ulw)1 f H W (adl) MPOIG K (a) vl6�a f (seWup azlg ad1 W d (Y>I col a (sla) �Ij u6isa W Isp) rnolj loan lU K y (Y)adOl LL O z U4N!) JC F (ov) V. O (ulw) o (�)ON O,NNm R Q (VN!)Imarrm m m N m N of of m ai r m m ai m m of (�)�j V.N O m O ONN 00O O O N A. O < V O LL LL Z (UIW)�A�4U OOrm 01 N m r A O YI O N n U '31-U. 'J uam �mroea o0000 8 0 0 W Comm.-o m y C ('JV) ea ('� C V C o ooco N 0 O 0 Ol ulse Z W2 1 a m p luwd u6i5a G < < m NO H W W K r N 0 APPENDIX C Gaoway Planning. Architecture. Engineering. HYDRAULIC CALCULATIONS Ga€oway Planning, Architecture, Engineering. SWALE CAPACITY CALCULATIONS 1 1 1 1 1 1 1 1 1 1 1 1 1 1 L i 1 1. 1 Vegetated Swale Project Description I Friction Method Manning Formula Solve For Discharge ?Input Data Roughness Coefficient 0.035 Channel Slope 0.005 ft/ft Normal Depth 1.00 ft Left Side Slope 4.00 ft1ft (H:V) Right Side Slope 3.00 ft/ft (H:V) Normal Depth (ft) Discharge (fN/s) Velocity (ft/s) Flow Area (ft') Wetted Perimeter (ft) Top Width (ft) 0.00 0.00 0.00 0.00 0.10 0.01 0.40 0.04 0.73 0.70. 0.20 0.09 0.63 0.14 1.46 1.40 0.30 0.26 0.83 0.32 2.19 2.10 0.40 0.56 1.00 0.56 2.91 2.80 0.50 1.02 1.16 0.88 3.64 3.50 0.60 1.65 1.31 1.26 4.37 4.20 0.70 2.49 1.45 1.72. 5.10 4.90 0.80 3.55 1.59 2.24 5.83 5.60 0.90 4.87 1.72 2.84 6.56 6.30 1.00 6.45 1.84 3.50 7.29 7.00 is ±0.6 cfs. erefore, velocity is .0 ft/sec. Bentley Systems, Inc. Haestad Methods SoBdkftg:fiikft Master VBi (SELECTseries 1) [08.11.01.03] 11/1/2016 9:49:52 AM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1.203-755.1666 Page 1 of 1 Vegetated Swale ,Project Description Friction Method Manning Formula Solve For Discharge ;Input Data Roughness Coefficient 0.035 Channel Slope 0.007 ftfft Normal Depth 1.00 ft Left Side Slope 4.00 H:V Right Side Slope 3.00 H:V L Normal Depth (ft) Discharge (fP/s) Velocity (ft1s) Flow Area (ft')_ Wetted Perimeter (ft) Top W idth (ft) 0.00 0.00 0.00 0.00 0.10 0.02 0.47 0.04 0.73 0.70 0.20 0.10 0.75 0.14 1.46 1.40 0.30 0.31 0.98 0.32 2.19 2.10 0.40 0.66 1.18 0.56 2.91 2.80 0.50 1.20 1.37 0.88 3.64 3.50 0.60 1.95 1.55 1.26 4.37 4.20 0.70 2.95 1.72 1.72 5.10 4.90 0.80 4.21 1.88 2.24 5.83 5.60 0.90 5.76 2.03 2.84 6.56 6.30 1.00 7.63 2.18 3.50 7.29 7.00 I1.33` Q. for A2: 4.0 cfs 1.33` Q,. for A4: 3.3 cfs Bentley Systems, Inc. Haestad Methods SollbibA dikerMaster V8i (SELECTseries 1) [08.11.01.03] 4/19/2018 3:50:06 PM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1.203.755.1666 Page 1 of 1 Vegetated Swale ;Project Description Friction Method Manning Formula Solve For Discharge Input Data ----- - ---- - --- Roughness Coefficient 0.035 Channel Slope 0.005 ft/ft Normal Depth 1.00 . ft Left Side Slope 4.00 H:V Right Side Slope 3.00 H:V Normal Depth (ft) Discharge (fP/s) Velocity (fVs) Flow Area (ft') Wetted Perimeter (ft) Top Width (ft) 0.00 0.00 0.00 0.00 0.10 0.01 0.40 0.04 0.73 0.70 0.20 0.09 0.63 0.14 1.46 1.40 0.30 0.26 0.83 0.32 2.19 2.10 0.40 0.56 1.00 0.56 2.91 2.80 0.50 1.02 1.16 0.88 3.64 3.50 0.60 1.65 1.31 1.26 4.37 4.20. 0.70 2.49 1.45 1.72 5.10 4.90 0.80 3.55 1.59 2.24 5.83 5.60 0.90 4.87 1.72 2.84 6.56 6.30 1.00 6.45 1.84 3.50 7.29 7.00 1.33' Q,, for Al: 1.6 cfs 1.33" Q,. for Al, cfs Bentley Systems, Inc. Haestad Methods SoBPiotle44-d6arMaster V8i (SELECTseries 1) [08.11.01.031 4/19/2018 3:49:22 PM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203.755-1I666 Page 1 of 1 CULVERT SIZING Ga€oway Planning. Architecture. Engineering. s Culvert Report Hydraflow Express Extension for Autodesk0 AutoCAD@ Civil 3DOO by Autodesk, Inc DP Al 1 (2) - 8 in. HDPE Culverts Invert Elev Dn (ft) = 9.23 Calculations Pipe Length (ft) = 56.81 Qmin (cfs) = 0.00 Slope (%) = 0.44 Qmax (cfs) = 1.20 Invert Elev Up (ft) = 9.48 Tailwater Elev (ft) = Crown Rise (in) = 8.0 Shape = Circular Highlighted Span (in) = 8.0 Qtotal (cfs) = 1.20 No. Barrels = 2 Qpipe (cfs) = 1.20 n-Value = 0.013 Qovertop (cfs) = 0.00 Culvert Type = Circular Concrete Veloc Dn (ft/s) = 1.72 Culvert Entrance = Groove end projecting (C) Veloc Up (ft/s) = 1.89 Coeff. K,M,c,Yk = 0.0045, 2, 0.0317, 0.69, 0.2 HGL Dn (ft) = 9.90 HGL Up (ft) = 10.05 Embankment Hw Elev (ft) = 10.12 Top Elevation (ft) = 10.67 Hw/D (ft) = 0.96 Top Width (ft) = 35.00 Flow Regime = Outlet Control Crest Width (ft) = 35.00 1 0 DP Al 1 (2) - 8 in. HOPE Culverts Hw Ceptn irt: 1.52 1 02 0.52 0.02 .048 -0.98 5 10 15 20 25 30 35 40 46 5o 55 60 65 70 75 80 - Crculer Culvert HGL Embank Reach (RI t] Veloc Depth HGL Total Pipe Over Dn Up Dn Up Dn Up (cfs) ids) (CIS) MIS) (ft/s) (in) (in) (ft) (ft) 0.40 0.40 0.00 0.57 2.19 8.00 2.47 9.90 9.69 0.80 0.80 0.00 1.15 2.69 8.00 3.53 9.90 9.77 1.20 1.20 0.00 1.72 1.89 8.00 6.85 9.90 10.05 ' Hydraflow Express - DP Al 1 (2) - 8 in. HDPE Culverts - 04/19/18 1 HGL ' Hw HWID (ft) ' 9.76 0.42 9.89 0.62 10.12 0.96 ' Hydraflow Express - DP Al 1 (2) - 8 in. HDPE Culverts - 04/19/18 2 Culvert Report 1 1 Hydraflow Express Extension for Autodesk® AutoCADO Civil 3D0 by Autodesk, Inc DP A2 1 (3) - 8 in. HDPE Culverts Invert Elev Dn (ft) = 8.63 Calculations Pipe Length (ft) = 14.74 Qmin (cfs) = 0.00 Slope (%) = 0.47 Qmax (cfs) = 3.00 Invert Elev Up (ft) = 8.70 Tailwater Elev (ft) = Crown Rise (in) = 8.0 Shape = Circular Highlighted Span (in) = 8.0 Qtotal (cfs) = 3.00 No. Barrels = 3 Qpipe (cfs) = 3.00 n-Value = 0.013 Qovertop (cfs) = 0.00 Culvert Type = Circular Concrete Veloc Dn (ft/s) = 2.87 Culvert Entrance = Groove end projecting (C) Veloc Up (ft/s) = 2.86 Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2 HGL Dn (ft) = 9.30 HGL Up (ft) = 9.40 Embankment Hw Elev (ft) = 9.43 Top Elevation (ft) = 9.80 Hw/D (ft) = 1.09 Top Width (ft) = 8.00 Flow Regime = Inlet Control Crest Width (ft) = 8.00 Elw (ft) DP A2 1 (3) - 9 in. HDPE Culverts Circular Culvert HGL Embank H. Depth lft) 1 30 ac Reach (ft( O Veloc Depth HGL Total Pipe Over Dn Up Dn Up Dn Up (cfs) (cfs) (cfs) (ft/s) (ft/s) (in) (in) (ft) (ft) 0.50 0.50 0.00 0.48 2.08 8.00 2.24 9.30 8.89 1.00 1.00 0.00 0.96 2.54 8.00 3,21 9.30 8.97 1.50 1.50 0.00 1.43 2.89 8.00 3.97 9.30 9.03 2.00 2.00 0.00 1.91 3.20 8.00 4.61 9.30 9.08 2.50 2.50 0.00 2.39 2.39 8.00 8.00 9.30 9.37 3.00 3.00 0.00 2.87 2.86 8.00 8.00 9.30 9.40 1 1 1 1 1 1 1 1 1 i 1 1 iHydraflow Express - DP A2 (3) - 8 in. HDPE Culverts - 04/19/18 1 HGL Hw Hw/D (ft) 8.95 0.38 9.07 0.56 9.17 0.70 9.26 0.84 9.47 1.16 9.43 1.09 ' Hydraflow Express - DP A2 1 (3) - 8 in. HDPE Culverts - 04/19/18 2 Culvert Report Hydraflow Express Extension for Autodesk® AutoCADO Civil 3D0 by Autodesk, Inc DP A3 1 (3) - 8in. HDPE Culverts Invert Elev Dn (ft) = 8.05 Calculations Pipe Length (ft) = 46.15 Qmin (cfs) = 0.00 Slope (%) = 2.36 Qmax (cfs) = 3.50 Invert Elev Up (ft) = 9.14 Tailwater Elev (ft) = Crown Rise (in) = 8.0 Shape = Circular Highlighted Span (in) = 8.0 Qtotal (cfs) = 3.50 No. Barrels = 3 Qpipe (cfs) = 3.50 n-Value = 0.013 Qovertop (cfs) = 0.00 Culvert Type = Circular Concrete Veloc Dn (ft/s) = 3.34 Culvert Entrance = Square edge w/headwall (C) Veloc Up (ft/s) = 4.06 Coeff. K,M,c,Yk = 0.0098, 2, 0.0398, 0.67, 0.5 HGL Dn (ft) = 8.72 HGL Up (ft) = 9.65 Embankment Hw Elev (ft) = 10.02 Top Elevation (ft) = 10.24 Hw/D (ft) = 1.33 Top Width (ft) = 35.00 Flow Regime = Inlet Control Crest Width (ft) = 35.00 FJN in) 11 00 1060 10Do 950 9 D0 860 8 DO 750 DP A3 1 (3) - Bin. HDPE Culverts Circular Culvert HGL Embank H. Death (n) 1 86 1 36 086 036 la O Velx Depth HGL Total Pipe Ova Dn Up Dn Up DTUP (ds) (efs) (ds) (ft/s) MIS) (in) (in) ((ft) 0.50 0.50 0.00 0.48 2.08 8.00 2.24 8.72 9.33 1.00 1.00 0.00 0.96 2.54 8.00 3.21 8.72 9.41 1.50 1.50 0.00 1.43 2.89 8.00 3.97 8.72 9.47 2.00 2.00 0.00 1.91 3.20 8.00 4.61 8.72 9.52 2.50 2.50 0.00 2.39 3.48 8.00 5.18 8.72 9.57 3.00 3.00 0.00 2.87 3.77 8.00 5.69 8.72 9.61 3.50 3.50 0.00 3.34 4.06 8.00 6.14 8.72 9.65 1 1 ' Hydraflow Express - DP A3 1 (3) - 8in. HDPE Culverts - 04/19/18 HGL Hw Hw/D (ft) 9.39 0.37 9.51 0.55 9.61 0.71 9.71 0.86 9.81 1.00 9.91 1.15 10.02 1.33 ' Hydraflow Express - DP A3 1 (3) - 8in. HDPE Culverts - 04/19/18 2 Culvert Report Hydraflow Express Extension for Autodeske AutoCADOa Civil Me by Autodesk, Inc. Thursday, Apr 19 2018 DP A4 1 (3) - 8in. HDPE Culverts Invert Elev Dn (ft) = 8.39 Calculations Pipe Length (ft) = 62.13 Qmin (cfs) = 0.00 Slope (%) = 0.56 Qmax (cfs) = 2.50 Invert Elev Up (ft) = 8.74 Tailwater Elev (ft) = Crown Rise (in) = 8.0 Shape = Circular Highlighted Span (in) = 8.0 Qtotal (cfs) = 2.50 No. Barrels = 3 Qpipe (cfs) = 2.50 n-Value = 0.013 Qovertop (cfs) = 0.00 Culvert Type = Circular Concrete Veloc Dn (ft/s) = 2.39 Culvert Entrance = Groove end projecting (C) Veloc Up (ft/s) = 2.58 Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2 HGL Dn (ft) = 9.06 HGL Up (ft) = 9.32 Embankment Hw Elev (ft) = 9.38 Top Elevation (ft) = 10.90 Hw/D (ft) = 0.97 Top Width (ft) = 35.00 Flow Regime = Inlet Control Crest Width (ft) = 35.00 Elev ircl 6 Q DP A4 1 (3) - 8in. HDPE Culverts 0 5 10 15 20 25 30 35 40 46 60 Circularculvert HGL Embank H. Depth IRj 2.26 1 76 26 076 0.26 -C 24 .0 74 -1 24 56 60 66 70 75 8C 85 Reach Ip -- O Veloc Depth HGL - - Total -- Pipe- - - -- Over On _ Up Dn - Up On -- Up (cfs) (cfs) (cfs) M/S) (fUs) (in) (in) (ft) (ft) 0.50 0.50 0.00 0.48 2.08 8.00 2.24 9.06 8.93 1.00 1.00 0.00 0.96 2.54 8.00 3.21 9.06 9.01 1.50 1.50 0.00 1.43 2.89 8.00 3.97 9.06 9.07 2.00 2.00 0.00 1.91 3.20 8.00 4.61 9.06 9.12 2.50 2.50 0.00 2.39 2.58 8.00 6.97 9.06 9.32 ' Hydraflow Express - DP A4 1 (3) - 8in. HDPE Culverts - 04/19/18 1 HGL Hw Hw/D (ft) 8.99 0.38 9.11 0.56 9.21 0.70 9.30 0.84 9.38 0.97 ' Hydraflow Express - DP A4 1 (3) - 8in. HDPE Culverts - 04/19/18 I Gal-loway Planning. Architecture. Engineering. e DETENTION POND SIZING t 9 u t Modified FAA Method- Storage Colume Calculations ' Project Number: HPB01.01 Date: 12/19/2017 Project Location: Fort Collins, Colorado Calculations By: H. Feissner ' Pond Description: Basin A5 User Input Cell: BIL7 ext ' Inputs I Tributary Area Output I Detention Volume Return Period for Detention Control: 100-year Required Storage, cubic feet: 9385 ' Catchment'C': 0.72 Required Storage, ac-ft: 0.22 Catchment Drainage Area, ac: 1.84 Release Rate, cfs: 1.2 Storm Duration minutes Time seconds Rainfall Intensity in/hr Inflow Volume cubic feet Average Outflow cubic feet Storage Volume cubic feet Storage Volume acre-feet 5 300 9.95 3955 360 3595 0.08 10 600 7.72 6136 720 5416 0.12 151 900 6.52 7774 1080 6694 0.15 20 1200 5.60 8903 1440 7463 0.17 25 1500 4.98 9896 1800 8096 0.19 30 1800 4.52 10779 2160 8619 0.20 35 2100 4.08 11351 2520 8831 0.20 40 2400 3.74 11891 2880 9011 0.21 45 2700 3.46 12376 3240 9136 0.21 501 3000 3.23 12837 3600 9237 0.21 55 3300 3.03 13247 3960 9287 0.21 60 3600 2.86 13640 4320 9320 0.21 65 3900 2.71 14002 4680 9322 0.21 70 4200 2.59 14411 5040 9371 0.22 75 4500 Z48 44785 5400 9385 0.22 80 4800 2.38 15135 5760 9375 0.22 851 5100 2.29 15472 6120 9352 0.21 90 5400 2.21 15810 6480 9330 0.21 95 5700 2.13 16084 6840 9244 0.21 100 6000 2.06 16375 7200 9175 0.21 105 6300 2.00 16692 7560 9132 0.21 110 6600 1.94 16963 7920 9043 0.21 115 6900 1.88 17185 8280 8905 0.20 1201 7200 1.84 17551 8640 8911 0.20 100-year Orifice Plate I DP A5 Project Description Soive For -a-re Input Data Headwater Elevation 5109.60 ft Centroid Elevation 5107.84 ft Tailwater Elevation 5107.60 ft Discharge Coefficient 0.64 Diameter 0.475 ft Results Discharge 1.21 f 3/s Headwater Height Above Centroid 1.76 ft Tailwater Height Above Centroid -0.24 ft Flow Area 0.18 ft' Velocity 6.82 f /s Bentley Systems, Inc. Haestad Methods So®diU1eQF+WaMaster V8i (SELECTseries 1 ) [08.11.01.03] 12119/2017 11:15:09 AM 27 Siemens Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 1 Emergency Spillway I DP A5 Project Description Solve For Discharge Input Data Headwater Elevation 5109.80 ft Crest Elevation 5109.60 It Tailwater Elevation 5107.60 ft Crest Surface Type Paved Crest Breadth 0.50 ft Crest Length 40.00 ft Results Discharge 11.04 ft'/s Headwater Height Above Crest 0.20 ft Tailwater Height Above Crest -2.00 ft Weir Coefficient 3.09 US Submergence Factor 1.00 Adjusted Weir Coefficient 3.09 US Flow Area 8.00 IY Velocity 1.38 ft/s Wetted Perimeter 40.40 ft Top Width 40.00 ft Bentley Systems, Inc. Haestad Methods So6@idteQFillwMaster V8i (SELECTseries 1( 108.11.01.03) 12/2612017 10:11:41 AM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 1 Detention Pond Stage -Storage Calculations Project Number: HPBO1.01 Project Location: Fort Collins. Colorado Date: 12/19/2017 Calculations By: H. Feissner Pond Description: Basin A5 User Input Cell: Blue Text Required Volume Water Surface Elevation Design Point: A' Design Storm: N/A Required Volume: 0 ft, r ft Design Storm: NIA Required Volume: 0 ft, r ft Design Storm: 100-year Required Volume: 9385 ft' ft Average End Area Method: Conic Volume Method: Contour Elevation Contour Area Depth Incremental Volume Cummulative Volume Incremental Volume Cummulative Volume Cummulative Volume ft ftz ft W ft3 W ft3 ac-ft 5107 6": 0 0 0 0 0 0.000 0.10 1 1 1 1 0.000 5�;7' IZS 0.10 7 8 6 7 0.000 5!�."�'" 166 0.10 30 37 28 34 0.001 5IOB "'r " 03 0.10 78 115 76 110 0.003 '.859 0.10 149 264 147 258 0.006 2634 0.10 226 491 225 483 0.011 .;a87 0.10 306 797 305 788 0.018 IL; 0.10 389 1186 388 1176 0.027 0.10 466 1652 465 1642 0.038 - 0.10 524 2176 524 2166 0.050 0.1D 567 2743 567 2732 0.063 . �:� t:�. 0.10 605 3348 605 3337 0.077 0.10 641 3989 641 3978 0.091 0.10 673 4661 673 4651 0.107 51 u9 0.10 706 5367 706 5356 0.123 :1: � Z 0.10 741 6108 741 6097 0.140 5!'1,'�,r. T;; .' 0.10 774 6882 774 6871 0.158 5 ! 0 y 1? 0.10 809 7691 809 7680 0.176 5109.1' ��! 0.10 843 8534 843 8523 0.196 5 '- p:; "'n -1 ' I'� ' 0.10 885 9419 8851 9408 0.216 0.10 943 10362 943 10351 0.238 51101 5109.6 r c S109.1 Y W 0 '51086 5107.6 0 Stage -Storage I Site 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 Cummulative Volume, W G a m-00,1111"o w a y Planning. Architecture. Engineering. DRAINAGE MAPS + WEST PLUM PUD MEMORANDUM + VARIANCE APPLICATION 0 Ga€oway Planning. Architecture. Engineering. i DRAINAGE MAPS II I i RHODES II I I I I Emiw �nx M NBEADr)t Galloway ._ IA*-w 90TR ON oRanirg. PlchAECWre. Egnarig. \� 31WE. An sOAI, Sti@XR 1 : _ _ WEST P M STREET- �,co I WEST PLUM STREET- I_ I u, ° — APLANNIEDUNIT A PLANNED UNIT —I DEVE I CIPMENT - i DEVELOPMENT LEGEND: - � EX2 I - I E..T.•��aax EX, r ` 020 a,„ -- E011N WOIRMtl. BID ---------------- _� L Exi MEAL I o.m EX4 o.:: � oo `.. EX3 0.29 �; oicDIA. I - i' I a� 1.0As•� r I I I I, bl I I / I 4 w•It It 1 1•y j i I VALLEY HI SUBDIVISION BLOCK 4 54 f — - — ------------ -- — ... ... — --------------- ----- - - — - - — - - — - - — - - -- -- --—--—----F- - - — DRAINAGE SYMBOLS: z DID r�PpnOPnIEEmooT®R r.lw. _. eup�IMT.1 n.mmrmr pAq I �" ununuu41111111111111111 o�w.a aalaE..�m.Wx =WewEaEa9�. II F.I �u�xol c,Kh I. - PAIEMENTOJRIx Ej aro DRAINAGE SUMMARY TABLE I EXISTING CONDITION TIYYy eusarw r.. I.a•1 D9 T"` ♦mm Ipel 1,IIN~ IFNI C. ,ebl Y 191N IX1 am am 036 5..0 5.0 DIM 0.11 M 0.10 am O.m V d3 am DIM exe ate am 04e 6A SA 0.10 am FH an am aA n.1 m] am 1A9 M 1 am am mA T86 am Im HIGH PLAINS BUILDERS, LLC P.O. Box 2796 Gillette, WY 82717 307.257.2352 , J� F°e�oay� 1 0~ COPYRIGHT GAI�µ0� EOTTOf 9�E R owar. AND uar x01BE DURUDuwalm. USCLOGOOORRTHEAFETTENCOEaxODuFGALLO Oal TVENWTIENCDINFRIOEGPLLM4aY. CMYP DRiE NIO FIND E DBECUTED V.11 BE EHFORCEDaW %i05ECUTED. N J W LU co L W to c m co in JN SZ wz wg w Qma �o 0 N= o(r W2 NLL a Deb I u DwpM Y,n nohala •mow a..oy xe rn w wx• BOXo.vAlr EXISTING CONDITION DRAINA GE PLAN OF7 SHFFT __________-- WEST PLUM STREET- - A PLANNED UNIT i DEVELOPMENT I I WW- IS I I WEBB— S112 FOUEll y— c i „6 �-OE1 s �L 11 ` m,�o-00 — j � /066 3 � ° r"6 B] vdzx ' is I I I I ♦ I .I I II I � , I A4 , D,Y ,1 % I WEST -tA MST '-- A P NED UNIT 1 DEVI I OPMENT I *t , /1 „Of i i TE z I _µ_So WEBB Blow�. „EMILI IR A2� a6c a3B -- -- RW, — 1--A ♦--- - r—__BARTLETT FINE -- (PRIVATE paVE) F ♦ -� i YffiIAIBISYII! � •'.l J I / �I mA`I , jI � l ' NmlxcmwE LE `LL.I aollEaMrE I / I R�TA1mwwE --y—y y.--'1 E I � I I I I I I I I I I Y 1 URI �^I�I I ROWUl ISI I ' I I "IRuwEBURYLnn �— I ------------- I Az - �1I IF �` A5 D VALLEY HI .° \` ! SUBDIVISION Will c \ LCETEsTU, IA } BLOCK N E I� TRW .;;'i.I T AW 5'a on IJOO 044 mm— 1I a —TEUV —STREET— - __—_— -------------- ,T„„MI GallOWa�/ w NE RmA3gx; D. Planning. Archiredure. EngneM6g. 5265 RmMJ Rego, BM., Sub ra LM,BoIoMT. co area 970,8010 LEGEND: RMYD�DM.TN�mDDR —� �— I�I�DM,xBmTDR „ OT,IANNDPLoIIa.R ------- „„------- EERDP ep® STM T FmuE PDlno-mrY RNPoY4LN,M ---- -- DRAINAGE SYMBOLS: ManD All ase233 No lo[T D'INnAIKeFCliOalf .wNxE, YamROFNO „WDrtLmrtar LVR„ 81 DEbra Pum ,,•••••••••• r BDB6f NBWMAG OVERLONO NLp'ON �J uLOWD I E,OBG DREcra6wDPEn IN LIE MFm.O.PoNO R BILVEI NOTES: OY%E,A,BIP«E O ORRNI6NEgDY„RA „RIR„ hTm blob O ua - DETENTION POND SUMMARY TABLE SUMMARY TABLE I DEVELOPED CONDITION ]rb] aloa.b WA NBPM Cf CIO wivin F axN wilwyw (w") x] (NINE) GE00 ISBN) At 0.16 ON SITE BS so 01 12 A2 also ON O.W 7.9 6.0 0.6 JO AS 0" 0.0 10.1 ]] 0.7 36 `W am B.1 LB Ob m ]3 also0.a 11.o B.B 0J 1D B1 3OA10O 0.61mu ]2 6D Ob m 081 O.eo 1m a6 6A 1.0 IA rjr_ BOB V%JEL do CALL Union' NOTIEICATON CENTEACE COLORADO 10 swoR wRorSbelow. Call barore SOL dig. OR RURAL OR WCAVARE FUR TRE WARWAIM City of Fort Collins, Colaaan UTILITY PLAN APPROVAL IRfHho. OR ON✓m ON c,ECND B, .AAWI ®munr Wury D.M clEcvn By SEM"W'Ll w ZFECXED BY DM, w NEED Bo 61EI9EDBY EMIRF,14 Poor ask HIGH PLAINS BUILDERS, LLC P.O. Box 2796 Gillette, WY 82717 307.257.2352 COPYRIGHT MEBE F VN9 APE AN INSTRUMENT CE SERVICE AN D APE THE PROPERTY OF ® LLLOWAr AND Mgr NOT BE DU PLIGTED ED CA REPRODUCED NIIMWT ME WRRTEN WIN SEW OF WLLONVU COPYRIGHTS AN 0 KFIRME MENRWILL BE ENFROMOLED O PPOSECUIED. fn J J UL LL W W 0 LU m 0 Cn N Z Z LU J DO D_ a J — W = OLL If CEO beuelOmWpbn Ina "FOUR e i DRAINAGE P AN C9.0 N OF ]6SHEETS G a "Hi" o w ay Planning. Architecture. Engineering. WEST PLUM PUD MEMORANDUM Ga2111 oway ' Planning. Architecture. Engineering. / Memorandum To: Wes Lamarque From: Patrick Schoenecker Date: February 12, 2018 Re: West Plum Street P.U.D Swale Hydraulics As a part of the Elizabeth Street Farms Development Project (ESF), designs laid out by Galloway plan to discharge 2.40 cfs from the proposed site (Basin 61) to the north on Pear St. which would flow through the existing Swale behind lots 11, 12, and 13 of the West Plum Street P.U.D. Using the West Plum Street P.U.D.Drainage Report (WPDR), updated hydrology for the area, and current survey of the Swale in question, let this memorandum serve as proof that the Swale has capacity for the proposed additional 2.40 cfs. The WPDR can be found attached to this memo. In the WPDR, there exist a few numerical inconsistencies and errors, noted in the attached copy. The WPDR includes flow in the Swale that was clearly stated to be confined to Plum St. earlier in the report. The actual area draining to the Swale was also underestimated. The existing flow to the Swale is calculated using the rational method below: C = 0.45 (calculated in the WPDR) Tc = 10 mins (calculated in the WPDR) I = 7.72 in/hr (Table RA-7, 10 min Tc) A = 1.54 acres (see attached) Qioo. EC = CIA x 1.25 = (0.45 x 7.72 x 1.54) x 1.25 = 6.69 cfs Topographic survey was collected of the Swale on 2/7/2018. Several cross sections were taken from the Swale and the most.limiting cross section was used in Bentley ° Flowmaster to calculate flow depth. The depth is increased by 33% per CoFC regulations: Qroo. EC x 1.33 = 8.90 cfs D100. EC @ 8.90 cfs = 0.87 ft If the proposed flow from ESF Basin B1 is included, the flowrate and depth of flow in the Swale is calculated to be: Qtoo, Pc = Q70a, EC + QESF, B1 = 6.69 + 2.40 = 9.09 cfs The proposed depth of flow is calculated as: Qtoo, Pc x 1.33 = 12.09 cfs Dioo, Pc @ 12.09 cfs = 0.97 ft lik West Plum PUD Swale Hydrology.docx 1 of 2 Galloway & Company, Inc. • 970.800.3300 • 5265 Ronald Reagan Blvd., Suite 210 • Johnstown, CO 80534 • www.GallowayUS.com Ga oway / Memorandum Planning. Architecture. Engineering. Adjacent to the Swale, there are 2 window wells to the south' that are the lowest opening to the surrounding houses. These window wells were shot during the 2/7/2018 survey. The elevation, height above the invert of the Swale, and freeboard using the proposed hydrology is calculated as: Elevation Height above Freeboard Swale Invert 12.09 cfs Window #1 5104.58' 1.89' 0.92' Window#2 5104.84' 2.29' 1.32' The proposed increase in flow would result in a 0.1' increase in the WSEL in the Swale in a 100-yr event. As demonstrated by the flow calculations for the Swale, this is not an issue of capacity for the existing Swale. ' Further backup documentation can be made available upon request. Thank you for your consideration and please contact me if you would like to discuss this matter further. Than yo i Patrick Schoenecker, PE Civil Project Engineer 970-800-3304 patrickschoenecker@gallowayus.com West Plum PUD Swale Hydrology.docx 2of2 Galloway & Company, Inc. • 970.800.3300 • 5265 Ronald Reagan Blvd., Suite 210 • Johnstown, CO 80534 • www.GallowayUS.com '' '1 1' 0 �RorFTr OF 1=ingl Aamyed Report FORT COLt,1ATS afe DRAINAGE WVESTI ON FOR, WEST PLUM STREET - P.U.D. CITY OF FORT COLLINS, i 4RMER COUNTY, COLORADO Prepared for Vista Building Company P. O. Box 885 Fort Collins, Colorado 80522 May 14,1996 (Revised August 9,1996) Project No. PLA =195 - 96 ' tj ry I kl�� 150 E. 29th Street, #238 Loveland, Colorado 80538 Telephone: (970) 663 - 2221 11 1, Mr. Basil Y. Hamdan Stormwater Utility 235 Mathews P. 0. Box 580 Fort Collins, Colorado 80522-0580 August 8, 1996 Project No. PIA - 195 - 96 Dear Mr. Hamdan, M, The enclosed report represents the results of the drainage investigation for the proposed "West Plum Street - P.U.D." to be located in the City of Fort Collins, Larimer County, Colorado. This investigation was based upon the proposed site development plan; proposed site grading plan; on -site observations; and available topographic information. " The investigation was performed in accordance with the criteria established in the City of Fort Collins "Storm Drainage Design Criteria and Construction Specification Standards" manual. t' If you should have any questions, please feel free to contact this office. Respectfully Submitted, MESS Engineering Associates g111111t1IpU�jry ORE �ro - • 09 • Dennis R. Messner, P.E. .•8-/�.q(o ,�� DRM/mkm�4rys�+Dl/iAi��Ea�` Enclosures ' cc: Mr. Doug Viita 1' Civil and Environmental Engineering Consultants 't 150 E. 29th Street, Suite 238 Loveland, Colorado 80538 Telephone: (970j 663-2221 . --- • i XM Letter of Transmittal Table of Contents Scope Site Description "Historic" Conditions Proposed Development Erosion Control Measures Conclusions and Recommendations Drainage Summary Erosion Control Cost Estimate letter EXHIBITS Vicinity Map "Historic" Conditions Exhibit Proposed Conditions Exhibit Calculations ii 1 SCOPE The following report represents the results of a drainage investigation for a proposed single family residential development to be located in the North Half of Section 16, Township 7 North, Range 69 West of the 6th P.M.in the City of Fort Collins, Larimer County, Colorado. The investigation was performed for the project developer, Viita Building Company. The purpose of this investigation is to determine the effects of the proposed development on the area's existing drainage conditions and to determine the improvements, if any, and the appropriate sizing for the proposed improvements so that it may be incorporated with the construction of the project. The conclusions and recommendations presented in this report are based upon the proposed site development plan; proposed building construction plans; on -site observations; and the available topographic information. The analysis was performed in accordance with the City of Fort Collins "Storm Drainage Design Criteria and Construction Standards" manual. SITE DESCRIPTION Total site Area: 3.05 ac " The site is considered to be rectangular and contains approximately 3.05 acres, exclusive of the adjacent 2.5 acre tract to the South that is to remain undeveloped. The site's East-West dimension is approximately 395 feet and its North -South " dimension is 335 feet. The site abuts the southerly right-of-way of West Plum Street and the tract that is to remain undeveloped abuts the northerly right-of-way of West Elizabeth Street. The site is located in the CANAL IMPORTATION DRAINAGE BASIN. "HISTORIC" CONDITIONS The site is vacant and has been utilized as irrigated pasture. A small depression has been dug near the Northeast corner of the site to capture surface runoff for ' stock watering. The ground surface has been- roughly graded and a moderate ' ground cover of grasses is found on the parcel. The "historic" direction that the site slopes is from South to North. A small lateral ditch is situated along the crest of a hill adjacent to the southerly boundary of the development. The site is considered to be moderate with slopes ranging from 1 Wto 6 %. The major portion of the site currently drains onto West Plum Street. The run-off generated on the rear yards of the adjacent lots to the West and East flows onto the site and then flows northerly across the site to West Plum Street. The runoff from the tract to the South that is to remain undeveloped flows to the South and East toward West Elizabeth Street. An existing developed area of approximately one acre situated immediately West of the site contributes run-off to the street flow along the North side of the site. The run-off in the street flows to the East along Plum Street to the intersection with Timber Lane. The flow travels North along Timber Lane for ' approximately four hundred feet where it is intercepted by storm drain inlets. The run-off is directed through the inlets to an open drainage channel that flows easterly. 11 11 The proposed development of the site is to consist of developing thirteen single family residences to be located on the northern three acres of the site. The homes are to be considered as affordable housing. The average proposed lot size is approximately 7,000 square feet. The house "foot print" is anticipated to be from 1,200 square feet to 1,500 square feet depending on the style of house to be constructed. A paved driveway and attached two -car garage are to be constructed with each home. The proposed site plan indicates that a cul de sac is to be constructed at the southerly boundary of the site. The proposed development plan indicates that the southern two, and one-half acres of the site is to remain vacant. with a potential for future development.The cul de sac is intended ultimately Provide access to the southerly portion of the site that is to remain undeveloped. This investigation has not considered this as tributary to the development that is currently proposed. As previously stated the run-off from the site flows onto West Plum Street. There are no other drainage facilities available to accept run-off from the site. The current City policies require that the difference between the historic rate of run-off and the developed rate of run-off be detained onsite. The release rate is to be no greater than the 2 Year Storm historic rate. The City's policies normally require that the adjacent street flows be incorporated with the -onsite detention requirements. This policy applies most efficiently when the street construction and onsite detention are performed concurrently. In this instance, it is not physically feasible to combine the two flows since the flow generated on the streets can not be intercepted and directed into an on -site detention facility and then routed back into the curb and gutter. The area within the southerly half of the Plum Street right-of-way has been considered as tributary to the detention facility for sizing purposes. There are long term plans for improvements to be made within the Importation Canal Drainage Basin. These improvements could provide facilities that would eliminate the need to provide onsite detention for the proposed development. Therefore, the onsite detention facility may be considered to be temporary and may be better utilized for open space purposes when its function as a drainage facility is no longer necessary. 2 11 EROSION CONTROL MEASURES Erosion control considerations are based upon the short term activities that occur during construction and the long term measures that are to be placed for the life of the facility. The long term erosion control measures are the proposed methods and materials to be used to provide surface treatments for the driveways, parking areas, walkways and the landscaped open areas. Landscape materials and plantings in the open areas will provide a combination of ground covers to deter erosion. The anticipated construction schedule should have the site grading completed, within one (1) month after commencing construction. The schedule for construction activities is anticipated to be: September 15 - September 20, perform site grading; September 23;- October 5 install water and- sewer lines; October 7 - October 15 construct curb,'gutter and sidewalks and drainage related facilities; October 21 - October 24 place pavement; October 15 - October 25 install landscaping. The recommended short term erosion control methods to be incorporated with the construction activities consist of the following: upon completion of grading operations and at the time that the drainage outlet is installed a "Straw Bale Filter" is to be placed at the inlet; and a "Silt Fence .is to be placed along the northern boundary of the site in order to control and contain mud and debris onsite. Wind erosion measures are to consist of water application and roughening of exposed surfaces. 3 11 ', 11 CONCLU IONS AND RECOMMENDATIONS ry area: B and 2 (0.56 ac + 2.75 as = 3.31 ac) W. Plum Street and the rear yards along the west were not included in the detention pond tributary . The release rate calculations suggest that basin B included becasue Q2 for basin B as used to set the ntion pond release rate. 1. The proposed development will retain the "historic" drainage patterns. 2. The site is located in the IMPORTATION CANAL DRAINAGE BASIN. The site is not located within a defined floodway or flood plain. 3. All development is to be performed in accordance with City of Fort Collins criteria. A variance to the City's policies is requested from detention of adjacent street flows due to physical impracticality. 4. Onsite detention of storm water is required by the City of Fort Collins. The volume of run-off'to be detained is estimated to be 10,836 cu. ft. The detention volume has been determined based upon the calculated volume of run-off generated by a 100 Year Storm. The entire site, one-half of the adjacent W. Plum Street, and the adjacent rear yards at. the West side of the site have been considered as the tributary area to determine the volume of the detention pond. The calculated volume generated from the tributary area is to be released at a controlled rate determined by the sum of the `historic' rate of run-off from the site for a 2 Year Storm plus the rate of run-off for the rear yards of the area to the West of the site. The calculated release rate is 1.92 c.f.s. 5. The City of Fort Collins Standards for temporary erosion control measures are to be incorporated with the construction activities. Specifically, the following are to be incorporated in the site construction activities: a. A "Silt Fence" is to be placed along the northerly border of the site. b. "Straw Bale Filters" are to be placed at the the inlet end of the outfall pipe until inlet structures are in place. C. Water application is to be made to prevent dust during the site development phase of the project. d. Roughening of the exposed earth surfaces shall take place during the site development phase of the project. 4 STORM WATER DETENTION SUMMARY SITE DRAINS TO "IMPORTATION CANAL" DRAINAGE BASIN GROSS SITE AREA (includes V2 of W. Plum Street) = 144,935 Sq. Ft. = 3.31 Ac. ± NET SITE AREA = 132,858 Sq.Ft. = 3.05 Ac. ± HISTORIC "C" = 0.20 Basins B and 1 have the same area, the flow DEVELOPED "C" = 0.45 patterns suggest that basin B drains into the HISTORIC "Q2" = 1.39 c.f.s. existing detention pond. CRITERIA BASED DETENTION VOLUME = 10,836 Cu.Ft. ± PLAN DETENTION VOLUME = 10,937 Cu.Ft. MAXIMUM DEPTH OF DETAINED WATER = 2.25 Ft. @ Elevation 5097.50 PEAK DISCHARGE FROM DETENTION, Q = "HISTORIC" Q2 + QOFPSiTE = 1.92 c.f.s. ± 1.39cfs + 0.53cfs = 1.92cfs RUN-OFF SUMMARY Basin Area 1C' -QZ_ Q100 (Acres) (c.f.s.) (c.f.s.) A 0.80 0.45 0.67 1.92 B 0.56 0.45 0.53 1.51 C 0.40 0.45 0.38 1.08 1 0.56 0.45 0.63 3.75 2 2.75 0.45 3.09 8.97 Engineering Associates May 16, 1996 Project No. PLA-195-96 Mr. Basil Hamdan Stormwater Utility 't City of Fort Collins 235 Mathews P. O. Box 580 Fort Collins, Colorado 80522 - 0580 Re: West Plum Street - RU.D., Fort Collins, Colorado Dear Mr. Ham dan, The estimated cost for erosion control devices for the subject. site has been „ estimated to be: 1. Silt Fence 4751:f. ® $2.50/ft. _ $1,187.50 2. Straw Bale Filter, 2 Each ® $75.00/Ea. = 1 .0 Total $1,337.60 Cost ®150% = 1.5_x $1,337.'50 = $2,006.25 ' The cost to re -seed the 132,850 square foot site at $0.0298/sq.ft. _ $3,959.17 ' 150% of the re -seeding cost = 1.5 x $3,959.17 $5,938.75 '' 11. Therefore, the subject project's estimated erosion control security amount is determined to be $5,938.75. This amount is to be included as surety for the erosion control guarantee along with any other surety requirements that may be a part of the City's "Developer's Agreement" requirements. If you should have any questions or desire additional information, please feel free to contact this office. Submitted, igineering Associates --tom_' Dennis R. Messner, P.E. cc: Mr. Doug Viita, Viita Building Company Civil and Environmental Engineering Consultants 15d E. 29th Street. Suite 225 Loveland, Colorado 80538 - Telephone: (970) 663-2221 3 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 1- I ar PI P� �Cmr C1 he rry St �2her'y Ln Cherry St tx —71517— co v WCO Ott" it - A-P Briarwo 0 Oak St W olive live W tt W W W COL ulbr Am —am r �- Or co ji� L 11:�— S r PA S - L VICINTY MAP (Not -to -Scale) O Sycamore St Maple S -% Collins CI Layland Ct Cr: Vi WAk I Cr p- W t Plum Ph m PIUMV ZI W C.0 Bin: W Plum S S PO oe rzbt D4 d Ks - re.1, I Dr (2 C, W VICINTY M" Ibr WEST PLUM STREET - P.U.D. to be located in the North Half of Section 16, Township 7 North, Range 69 West of the 6th P3L in the City of Fort Collins, Larimer County, Colorado Alp cc , 0 MF 4. I 1S . 'Uj z W's0iCC1pY4s.M+J! I it1ABEi}i —35T � ae vi .5 i` ._ . (_n 1 Conc. Pt. "A" Conc. Pt. "B" ' (Offsite Run-off to W. Plum St.) (Combined Offsite & Onsite Run-off on W. Plum St.) ' Area = 0.8 Acres = Area=Offsite[0.8+0.6+0.4]+Onsite[3.3]=5.1 Acres �1 02 = 0.7 c.f.s. = 02 = 3.3 c.f.s. _ 0100 = 1.9 c.f.s.- 0100 = 10.7 c.f.s.= (oki(culazel ITTOBO 11 11 11 11 11 DRAINAGE INVESTIGATION CALCULATIONS t' Client: VIITA BUILDING COMPANY Project No: PLA-195-96 Project: WEST PLUM STREET - P.U.D. Date: 14-Mar-96 Location: N 1/2 16 - 7 - 69, City of Fort Collins, Larimer County, CO By. D.R.M. Rev. 6/28/96 This investigation is being performed to determine the required detention volume, discharge rates, channel and structure sizing for the subject project site. The site is located in the "Importation Canal" Drainage Basin. RATIONAL METHOD Runoff Coefficients, "C" Larimer County Storm -Water Management Manual Land Use Description "C" Building/Roofs 0.95 Drives and Walks 0.95 Gravel Surfaced 0.50 Undeveloped Auras 0.20 Grassed Landscaped Areas 0.15 RATIONAL METHOD Frequency Adjustment Factors Storm Return Period ears Freq. Factor "Cf 2 1.00 5 1.00 10 1.00 100 1.25 EXISTING CONDITIONS: (Note that only the northern 3 t acres of the site is considered in this investigation.) Building/Roof Street, Drives and Walks Gravel Surfaced Landscape Undeveloped Open Areas Landscaped Areas Area= 0 Sq.Ft. Area= 0 Sq.Ft. Area= 0 Sq.Ft. Area= 144,395 Sq.Ft. 'Area = 0 Sq.Ft. TOTAL SITE AREA Area 144,395 Sq.Ft. Avg. C2 = ([(0.90 x 8,845)+(0.20 x 135,550)] + 144,395) x 1.00 Avg. C2 = 0.20 Avg. C5 = ([(0.90 x 8,845)-+(0.20 x 135,550)] + 144,395) x 1.00 Avg. C5 = 0.20 Avg. C10 = ([(0.90 x 8,845)+(0.20 x 135,550)] + 144,395) x 1.00 Avg. C10 = 0.20 Avg. C100 = ([(0.90 x 8,845)+(0.20 x 135,550)] + 144,395) X 1.25 Avg. C100 = 0.25 (Existing W. Plum St.) 3.31 Acres Page 1 of 7 11 11 DRAINAGE INVESTIGATION CALCULATIONS Client: VIITA BUILDING COMPANY Project No: PLA-195-96 Project WEST PLUM STREET - P.U.D. Date: 14-Mar-96 Location: N 1/2 16 - 7 - 69, City of Fort Collins, Larimer County, CO By. D.R.M. Rev. 8/9/96 EXISTING CONDITIONS: (cont.) Time of Concentration Consider sheet flow across site from South to North L = 420 ft. Elev. Diff. 5106 - 5096 = 10.00 ft. Slope, S = 2.38 % T= 1.87(1.1-CCf)qL+(SAl/3)=1.87(1.1-(0.25x1.00))4143+(2.38A1/3)= 25.84 Minutes Since surrounding area is developed consider for 'urbanized condition as a check Tc = L / 180 + 10 for'urbanized' condition with longest flow path considered Length. L = 600 ft. Tc = 600 / 180 + 10 = 13.33 minutes Average of the two methods = (24.41 + 13.33) / 2 = 19.59 minutes USE Tc = 1S minutes since area is mostly developed Rainfall Intensities based upon 15 minute Time of Concentration: I2 = 2.10 in./hr. I5 = 3.00 in./hr. I10 = 3.70 in./hr. I100 = 6.00 in./hr. Determine Run-off from Site under present conditions: Q = CIACf Offsite Run-off @ Existing Conditions: Q2=0.20x2.10x3.31x1.00= 1.39 CIS. Q5 = 0.20 x 3.00 x 3.31 x 1.00 = 1.99 c.f.s. Q10 = 0.20 x 3.70 x 3.31 x 1.00 = 2.45 CIS. Q 100 = 0.20 x 6.00 x 3.31' x 1.25 = 4.97 c.f.s. Area "B": Consider the run-off generated from the rear lot areas of the single-family residential lots immediately West of the Site. Area = 65 x 375 + 43,560 = 0.56 Acres Time of Concentration = 15 minutes from previous calculations. "C" = 0.45 from Table 3-2 Page 2 of 7 DRAINAGE INVESTIGATION CALCULATIONS tClient:- Project No: PLA-195-96 VIITA BUILDING COMPANY Project: WEST PLUM STREET - P.U.D. Date: 14-Mar-96 ' ' Location: N 1/2 16 - 7 - 69 City of Fort Collins, Larimer County. CO By D.R.M. Rev. 8/9/96 EXISTING CONDITIONS: (cunt.) Area "B": Q = CIACf Q2 = 0.45 x 2.10,x 0.56 x 1.00 = 0.53 Us. Q5 = 0.45 x 3.00 x 0.56 x 1.00 = 0.76 c.f.s. Q10 = 0.45 x 3.70 x 0.56 x 1.00 = 0.93 c.f.s. ', Q 100 = 0.45 x 6.00 x 0.56 x 1.25 = 1.51 c.f.s. Area "C": Consider the run-off generated from the rear lot areas of the single-family residential lots immediately East of the Site. Area = 50 x 350 + 43,560 = 0.40 Acres Time of Concentration = 15 minutes from previous calculations. "C" = 0.45 from Table 4.2.6-1 Area "C": Q = CIACf Q2 = 0.45 x 2.10 x 0.40 x 1.00 = 0.38 c.f.s. Q5 = 0.45_ x 3.00 x 0.40 x 1.00 = 0.54 c.f.s. Q10 = 0.45 x 3.70 x 0.40 x 1.00 = 0.67 c.f.s. Q100 = 0.45 x 6.00 x 0.40 x 1.25 = 1.08 c.f.s. Area "A": Consider the run-off generated on the developed area to the West that drains onto Plum Street from Rocky Road. Time of Concentration = L / 180 + 10 Tc = (550 / 180) + 10 = 13.06 Minutes Length, L = 550 feet Therefore consider Tc = 15 minutes Area = ((425 x 75) + (50 x 60)] / 43,560 = 0.80 Acres Therefore the gutter flow from the West: Area "A": Q = CIACf Q2 = 0.45 x 2.10 x 0.80 x 1.00 = 0.67 c.f.s. Q5 = 0.45 x 3.00 x 0.80 x 1.00 = 0.96 c.f.s. Q10 = 0.45 x 3.70 x 0.80 x 1.00 = 1.18 c.f.s. Q100 = 0.45 x 6.00 x 0.80 x 1.25 = 1.92 c.f.s. Page 3 of 7 DRAINAGE INVESTIGATION CALCULATIONS Client: VIITA BUILDING COMPANY Project No: PLA-195-96 Project: WEST PLUM STREET - P.U.D. Date: 14-Mar-96 Location: N 1/2 16 - 7 - 69. City of Fort Collins, Larimer County, CO By: D.R.M. Rev. 8/9/96 PROPOSED CONDITIONS: Building/Roof Area 18,600 Sq.Ft. Drives and Walks . Area= 36,400 Sq.Ft. Gravel Surfaced Landscape Area = 0 Sq.Ft. Undeveloped Open Areas Arm = 0 Sq.Ft. Landscaped Arm Area= 89,395 Sq.Ft. TOTAL SITE AREA Area 144,395 Sq.Ft. = 3.31 Acres Avg. C = ((0.95 x 18,600)+(0.95 x 36,400)+(0.50 x 0)+(0.35 x 0)+(0.20 x 89,395)] + 144395 Avg. "C" = 0.45 Flow path through back yard swales from Lots 6 to 2 and then in concrete pan to detention pond, therefore, Tc = 10 minutes 12 = 2.50 in./hr. I5 = 3.65 in/hr. I10 = 4.45 in./hr. I WO = 7.25 in./hr. Determine Peak Rate of Run-off at Proposed Condition: Area #1 - Area that is to flow undetained onto W. Plum street: Area #1= 0.56 acres Q2 = 0.45 x 2.50 x 0.56 x 1.00 = 0.63 c.f.s. Q5 = 0.45 x 3.65 x 0.56 x 1.00 = 0.92 c.f.s. According to the W. Plum PUD Q10 = 0.45 x 4.45 x 0.56 x 1.00 = 1.12 c.f.s. drainage plan, there is a high point in Pear St. that will keep Q100 = 0.45 x 7.25 x 0.56 x 1.2�1.83 c` this flow in Plum St. See last sheet of this report. Area #2 - Area onsite that drains to the proposed detention pond: Area #2 = 2.75 acres Q2 = 0.45 x 2.50 x 2.75 x 1.00 = 3.09 c.f.s. Q5 = 0.45 x 3.65 x 2.75 x 1.00 = 4.52 c.f.s. Q10 = 0.45 x 4.45 x 2.75 x 1.00 = 5.51 c.f.s. Q100 = 0.45 x 7.25 x 2.75 x 1.25 = 8.97 c.f.s. They forgot to multiply by 1.25 (even though it is in the equation). Should be 2.28 cfs. Page 4 of 7 0 11 DRAINAGE INVESTIGATION CALCULATIONS Client: VIITA BUILDING COMPANY Project No: PLA-195-96 Project: WEST PLUM STREET - P.U.D. Date: 14-Mar-96 Location: N 1/2 16 - 7 - 69, City of Fort Collins, Larimer County, COBy: D.R.M. Rev. 8/9/96 DETENTION VOLUME CALCULATION FOR PROPOSED SITE CONDITIONS QRelease = Q2 (Exist. Conditions) + Q Offsite thru Det. Pond = 1.39 + 0.53 = 1.92 c.f.s. At Q100 Proposed = CIACf = OA5 x I x 3.31 x 1.25 = 1 86 x I (in./hr.) Time min. Rainfall Int., I in./hr. Q100 Prop. c.f.s. Vol. @ Q100 cu.ft Q Rel. @ 2 Yr. c.f.s. Vol. Rel. cu.ft Vol. Diff. cu.ft. 10 7.10 13.21 7,926 1.92 1.152 6,774 15 6.00 11.16 10,044 1.92 1.728 8,316 20 5.15 9.58 11,496 1.92 2 304 9,192 25 4.55 8.46 I2,690 1.92 2,880 9.810 30 4.10 7.63 13,734 .1.92 3,456 10,278 40 3.45 6.42 15 408 1.92 4 608 10,800 50 2.95 5.49 16 470 1.92 5 760 10,710 60 2.65 4.93 17,748 1.92 6,912 10,836 70 2.35 4.37 18,354 1.92 8.064 10,290 80 2.15 4.00 19,200. 1 1.92 9.216 9,984 90 1 1.95 3.63 19,602 1.92 10,368 9 234 100 1 1.75 1 3.26 19,560 .1.92. 11520 8,040 110 1 1.60 1 2.98 19,668 1.92 12,672 6 996 120 1 1.45 1 2.70 19,440 1.92 13,824 5 616 Therefore, a minimum of 10,836 cu. ft. of Detention Storage Volume is desired for the site. DETERMINE POND SIZE: High Water Surface Area, At (175 x 40) = 7,000 sq.fL Pond Bottom Surface Area, Ab (150 x 20) = 3,000 sq.ft. Max Depth, h = 2.25 ft. Vol. = 1/3 ( Ab + At + 4AbAt) h = 10,937 cu.ft. 10,937 - 10,836 Therefore, OK Provide minimum of 1.0 ft. freeboard or additional 33% of total volume for safety factor. Elevation of Low Point = 5095.25 Design Top of Berm Elev. w/ 1.0' freeboard = 5095.25 + 2.25 + 1.0 = 5098.50 To attain 33% of total volume an additional depth of approximately 1.0' would be required. Therefore, maintain 1.9 freeboard. 0 Page 5 of 7 11 11 11 11 11 DRAINAGE INVESTIGATION CALCULATIONS Client: VNTA BUILDING COMPANY Project No: PLA-195-96 Project: WEST PLUM STREET - P.U.D. Date. 14-Mar-96 Location: N 1/2 16 - 7 - 69, City of Fort Collins, Larimer County, CO By. D.R.M. Rev. 8/9/96 DETENTION OUTLET CALCULATION FOR PROPOSED SITE CONDITIONS . Determine sizes to provide control at the outlet from the Detention Pond. Determine Orifice Opening Area for Discharge at Q2: Orifice Equation: Q = CA 42gh h = Depth - 0.5' = 1.75 ft. Q Release = 1.92 c.f.s. C = 0.65 A = Q / (C42gh) = 1.92 / (0.65 4(2 x 32.2 x 1.751 = 0.28 sq fL With Round Opening A = m-A2 Radius, R = 4A/rc = 4 0.28/h = 0.30 ft. Radius, R = ft. x 12 in./ft. = 3.60 in. With Square Opening A = wA2 Width of Opening, W = dA = 40.28 = 0.53 ft. Width of Opening, W = ft. x 12 in./ft. = 6.36 in. Use 7.1/4" dia. Round Opening or 6-3/8" Square Opening for outlet control device. CHECK FLOW DEPTH IN PLUM STREET Q2 = 0.63 + 0.38 + 0.67 + 1.74 = 3.42 c.f.s. Q100 = 1.83 + 1.08 + 1.92 + 1.74 = 6.16 c.f.s. Theoretical Street Capacity, Q = 0.56 Z/n JS yA8/3 n = • 0.016 Z = 1 / Cross Slope = 1/0.02 = 50 11 S = Gutter Slope = 1.2 % = 0.012 ft. / ft. At Depth of Flow, y Minor Storm Allowable Depth, y = 6" = 0.5 ft. ' 1 Q = 0.56 x (50 / 0.016) x 40.012 x 0.5A8/3 = 30.19 c.f.s. 1 1 Reduction' Factor= Capacity Theoretical Capacity x Reduction Factor = 30.19 x 0.80 = 0.80 24.15 c.Ls. Design = 1 24.15 >> 6.16 Therefore, the existing street's Design Capacity greatly exceeds ' estimated flow for either the Minor or Major Storms. Page 6 of 7 11 DRAINAGE INVESTIGATION CALCULATIONS Project No: PLA-195-96 Client: VIITA BUILDING COMPANY Project: WEST PLUM STREET - P.U.D. Daze: 14-Mar-96 ' ' Location: N 1/2 16 - 7 - 69 City of Fort Collins, Larimer County, CO By: D.R.M. Rev. 8/9/96 CROSS PAN CAPACITY AT PEAR STREET At 3" Flow Depth Pan Slope, S = 0.007 ft./ft. Pan Area, A = 3.06 sq. ft. The area that is used here is low. According to the drainage plan in this report, the area Wetted Perimeter, Wp = 24.5 ft. that should be used is 1.54 ac. Also, as R = A / Wp = 3.06 / 24.5 = 0.125 ft. , stated on page 4 of this repo the 1.83 cfs should not be included in this flo ate. n = 0.016 Q=1,486/n A RA2/3 SAM = IA86x3. 0.125)A 0.007)Alf2/0.016= 5.94 c.f.s. Flow over Cross -Pan from West side of Pear Street " Q100 + Q Offsite = (0.45 x 7.25 x 1.0 x 1.25) + 1 = 5,91 c.f.s. 5.94 - 5.91 Therefore depth of flow at 3" - OK Incorrect area " Determine Flow depth at Drainage Swale along rear lot -lines of Lots 11, 12 & 13 was used. (6"x10')l2 = 2.5sft At 6" Flow Depth Swale Slope, S = 0.01 ft./ft. ft. "V" shaped Swale 10 ft. wide by 6 in. Deep Swale Area, A = 5 sq. Wetted Perimeter, Wp = 10.05 ft. R=A/Wp=2.5/10.05= 0.50 ft. n = 0.025 IShould be 5.89 cfs ' ' Q=1.486/n A RA2/3 SAl/2 = 1.486x2.5x(0.25)A2/3x(0.01)Al/2/0.025= from West Pear Street 18.72 c.f.s. Flow over Cross -Pan side of Q100 + Q Offsite = (0.45 x 7.25 x 1.0 x 1.25) + 1.83 = 5.91 c.f.s. Q x 1.33 = 5.91 x 1.33 = 7.86 c.f.s. 18.72 >> 7.86 Therefore depth of flow less than 6" - OK Page 7 of 7 11 RAINFALL PERFORMANCE STANDARD EVALUATION PROJECT: West Plum Street - P.U.D. STANDARD FORM A COMPLETED BY: Messner Engineering Associates DATE: 3-14-96 DEVELOPED ERODIBILITY Asb Lsb Ssb Lb Sb PS SUBBAgIN ZONE (ac) (ft) ($) (feet) ($) M Entire Moderate 3.05 525 1.9% 79.6 Site MARCH 1991 8-14 DESIGN CRITERIA EFFECTIVENESS CALCULATIONS PROJECT: West Plum Street - P.U.D. STANDARD FORM B COMPLETED BY: Mcssner Engineering Associates DATE: 3-14-96 Erosion Control C-Factor P-Factor Method Value Value Comment Bare Soil 1.00 1.00 Road/Walks 0.01 1.00 Silt Barrier 1.00 0.50 Sediment Trap 1.00 0.50 Gravel Filter 1.00 0.80 MAJOR PS SUB AREA BASIN M BASIN (Ac) CALCULATIONS Entire 79.6 31:05 3.05 Bare Soil = 2.05 ac. Site Road/Walk = 1.0 ac. wtd 'C' _ (1.0 x 2.05) + (0.01 x 1.00) / 3.05 = 0.68 wtd 'P' = 0.5 x 0.5 x 0.8 = 0.2 EFF. _ (1 - (0.68 x 0.2)) x 100 = 86.4> 79.6 OR MARCH 1991 8-15 DESIGN CRITERIA '' CONSTRUCTION SEQUENCE PROJECT: West Plum Street - P.U.D. STANDARD FORM C 5EOUENCE. FOR 19 96 ONLY COMPLETED BY: Messner Engineering Assoc.DATE: 3-14-96 Indicate by use of a bar line or symbols when erosion control measures will be installed. Major modifications to an approved schedule may require submitting a new schedule for approval by the City Engineer. ' YEAR I 1996 I MONTH I JP.NIFEB I MARIAPR IMAY IJUNEIJULYIAUG ISEP IOCT INOV IDEC I '----------------------I-----------------------------------------------------------I OVERLOT GRADING 'WIND EROSION CONTROL Soil Roughing Perimeter Barrier. Additional Barriers Vegetative Methods Soil Sealant Other(Water Application) ' ' RAINFALL EROSION CONTROL STRUCTURAL: Sediment Trap/Basin Inlet Filters Straw Barriers Silt Fence Barriers Sand Bags Bare Soil Preparation Contour Furrows Terracing Asphalt/Concrete Paving Other ' VEGETATIVE: Permanent Seed Planting ' Mulching/Sealant Temporary Seed Planting Sad Installation ' Nettings/Mats/Blankets ' Other STRUCTURES: INSTALLED BY MAINTAINED BY ' VEGETATION/MULCHING CONTRACTOR ' DATE SUBMITTED APPROVED BY CITY OF FORT COLLINS ON HOI/SF-C:1989 Rxx RXR M 0 9 1 r is m smucmre[ ' - PoSIIIVW dOlC6 RM2 CMCC'lY CIE[ `_ eul{c7 PIP[ePx pNIQ VEMtIG mrtxm rt nr M2rtr a M wr a,,. MR wugeI AIWea.Y IAI lei 1 � mlunws l nu T L u' 1 n• ,f , ' ORIFICE PLATE DETAII, ' 11Nf�w-6V.F1 F _. 'I x oral se f � r, cavern ,uei S (' � it III ✓ / F'. - ^µ I I Y III III v C[ VIA1 aysn, 36f])P11.SS H6Ti4El=J ,mrvx[ ®ntuoYa rnm N sew • �z• w a-cwtsa. nc...r INLET STRUCTURE DETAIL . txvr w0a0 PAST' �F➢ rnPH� �3 ~ rin uv:�U�r FulYlu'Inll. {iw l�ti(,!il�Inj�l i SECTION AT, DETENTION POND OUTLET NOT re II .0 mcH R NIR n!1 1N P'ri.1C ne .cr. a TIT colaw. xows . ns wxuw nxuvtuR Aev. c , I n Nr, t eu - r n cenw so caa .ce¢ u I s Ya a revar. r t wvSo .wa aeevA ma'r � . i �, 2 sor•Iox vrtt 514T_FENCE DETAII SEMI yyAYG Xlx' MnM tl41[ A- Jt llk� I 111-P.3 :uax,u nWts , now tmu ttue env+mr nw xr'm OAcc m¢� a �""f r• it k . naoN"�iix'ut W', AM . �n ex �mlvA scleN.+xex�Oy�yF M401N,sc Der 9wt x Ax Aeu neelmin to Y Yet' T m"ma, S TaLi-5 mnO[g ee Iror➢S ,vas FILTER_STRA'N BALES A.(tEA_INLET N1 vaG MPSx ro eC f_';I Cvarmxa na xw PYItYNr" S �I3 ' I e2Y.20 �- ALLeGNNu mNIXa1 SECTION B AT QETENTION POND �etdf r --� OVE FLOW, SEC- , T636AM Ml SECTION i AT DE7E7.'?T14N,uOND yPIk II TO scALE - ' r 4 I 1 81 Ij \ Proposed Silt Fence ..W %H At . �1 S YA V II YI SECTION C-C IndNCeN rlonoNes) [+Isll,y re. IW. rum St.-1'.U.O i MgenY ewngarY M.Tct CdotYe Www! I CUullllg DILWNI on AUj1CW4 .11 tlxu doy .� W, ae VII]y Sbaxn ld a' Towv MIN u e S1 , upra:d Town d Slvms atu iXo iP,.wy Ua,,tury ^'MWlnxmn FocraWN.OMMI1,- 20%Mm. 1 t� 'so ilatll 1 MMlnu n _ 4wRLE__RT cnar N wSST nlAares Iv n0uHO5nin. n 3C _ - $CCT ON o . o °O (N., I. Sena Contour r -. V Inter�.eT a 1' v Existing Curti, -Proposed Silt Fence Cutter & Siderlk •,�, ate:_ =- G�G .� \ f' _.. sss Proposed Sidewalk Culvert - ✓ Overflow 1 A-- ,•.,ri Pnoposed 12"0 ;,.'l,:I,.' ''^.x / !u = ) ==_- _ ' ,S: N-12 Pipe Outlat 'A' �► -7. / TJEle 51 I-^ _ 2 510n In , �1 T. .F ev. � GI I B 1 5 �r '.oU t .. T J.5 '. d.J.i �� 96.6 -'C Area Elay Concrettee Pon H " - 1 L-e'hide 5097.75 Concr c ,in II ck5.4`� i Y T.05105.2 }l, >\ i.J L.5 5104. 5_- T.O.F..Elev r.. a 7 - -- _ 5T067 6t v r.-.. _ r 6.0 NOTE: SITE GRADING OPERATIONS FJHALL DE RESTRICTED TO THE "W. PLUM STREET - P.U.O." LIMITS. '40 GRAOIN�' OPERATIONS SHALL OCCUR ON THE PROPERTIES TO THE WEST OR EAST OF THE SITE. -I 0� yo eC. Inlet Stnacture w/ Orifice Plate tar Release 'Control (SEE DETAIL THIS SHEM 0^ 1 I 51CI STORM WATER DETENTION SUMMARY SITE DRAWS TO 'IMPORTATION CANAL' DRAINAGE WIN GROSS SITE AREA (Including 1/2 of adjacent W. Plum St.)m144.935 ea.R -3.31 Acme* NET SITE AREA . 132.850 Sq.F. a 3.05 Acree3 HISTORIC 'C' - 0,20 DEVELOPED 'C' . 0.45 e HISTORIC '02' - 139 cls. u T CRITERIA BASED DETENTION VOLUME m 10.536 cu.N.2 0 �. IP PLAN DUDMON VOLUME - 10.937 a.tt2 to �a L MAXIMUM DEPTH OF DUNNED WATER - 2.25 Ft. 0 Elevotlen 509-.50 oz tI PEAK DISCHARGE FROM DETENTION. 0 'HISTORIC' 02 + OORSTYE a2 a' 1.22 c.f.e.1 PUN-Or'F SUMMARY z JJ�� m ✓, O y C 0.40 0.45 0.38 1.08 g ° 1 0.50 0.45 0,63 1.73 2 275 0.45 3.09 5.07 n', I - City of Fort Collins, Colorado ! _ UTILITY PLAN APPROVAL IAPPRO✓_1) .c #A I n n 1 CHECKED BIco N LQc.'�.Sfr m o Woter 'Wdi1.- ter UIII;Fy' e o I Q13-4 CHECKED 5'r t4 roemwa er u Ilny ', � o y • 7drTix & ecreaTrnn " a N On u O ClIPC.KFD BY 0 aonsnurnory s[a3exw 'm y Q i w ° E o a M1 wy[[* W_ Puts %1_:2.UA xW1aNro ..I O W y ._ y sxu[.vc[,w reM ou. CaW1Te vI 1115LW.1eIwNaNx:Ai]9L uw ]. fix. IN ci e.nua ar usr or X ern u,w a rrvewe wa. wosla emxw .mtcea w_ [ wmw, ea uAux vcvrrNAncxs m In ex+mev aolMwu salwu sxW -.. Q c . xxw anr.aca IA eeII.& er as .31 acercty. I--," t'?''wl'"e,__',u_1rM�s'gLanr�(r»: L rn C _ u r- 5a.. _ WFRI,f VIAtIa 0001 T 0 pI 1XxC�pMil CPVIRU'. I ly� W Iq v.uo- ti O u: calm^n ew.ml ' pi a P+er meIIWL � I _�1 P l M.I •- W:1' CIWILx [ONfrW. 1 STYC`Wi 1M,bun zw.. {,a P.wry er vnsrm a G xtM .N eu O 0.. N alwr W O ",n slaurlm _-_-__ wmva• c• e T H �a � q, Xrl-�J 0 CD sae- Iyp tally Indicates Existing rF•-r-Y G'ound Surface Contour '.,510D % T picallyy indicates Proposed Finish Surface Contour ti- ti \"' Ty ically Indicates Proposed Curt, - rPutter & Sidawuld - 4 a - br' Typically Indicates Existinq Cue'b Gutter & Sidewalk u a DATE: MAY 16, i99t ._... K.._ Typically Indicates Sit FEnGE• SCALE: ,[>$_ NOTED Ty,�iccliv DRAW ./ Indicates Drainage ^IOW rilrEGtlgxl CHM,J: .D.fl.61, project Nc. Ty'picaily Indicates Drainage PtA-1D5-96 asin Limit SHEET 1 X r Typies Concentr cally IndicatInOn 4 f G A Pint Identifier J V ,,'x• c srvo env,.rti -, r !J uc nN rz 1 o nMuni1N 'e.� •. e . 4osnglr arax P.An Wlmv o,a@ av+ln nw[ rm M,CE wmrc amrlrc a mt NyfN w nc Iw[ I a,VVY .IVx a,Mie,e TRW w.( q' j 0' f-Sp' fe., CN• ' _ORIFICE PLATE DETAII, .aUU`oNaae�e[sua , s -0rnrax nut I rx• eA ounn Xee 4.. i NEInI ro LmA Il a-'J 1 PIAN, 1.- 1 - -- ,'nR[WI _ I s- -• � x _c- ti �c'X9a S S 3[cTlox !y XnXro•c[ S'Ncnux w"X N mM a IY wa wtcnw, mp rr _INLET STRUCTURE DETAIL_ wrnSRE_� PL'EF ra9xlC NCN. "rr nENCN N (D n NT iF MLL grt5: r4x r lgARAw Pv. 3,--cauPAt: Ncl:.. a LYnrn r[ o.¢f aa, n[X eo Innt,F .m v rt a Nurn-rY1. P_ Lr ctT x artc uo NrnYn W It mrc M1,1 Me. MrIaYC\r a[e•6M w rxt Nor wl +EOM yr IW x^I. NnK .Wtt.• IC" ,w am r•uvIYaSL 1 x •on.:rr s . xwu 1..]Woi'b N .N .Mu. nw,RGr ro .sow, ula ell el,ea mmnM- wu.Xt F[trox ntw SILT -FENCE DETAIL NOT -0 SC,:E NlItx wrM aNrt Afn�., A- -1 k :IIIUIIII k•4 , rM i eNlrO Ma wt A J MIS, X n MNE _ vw •W vwm wi SFW erwml i0w;a - 1 '1' r -- I.MSPELr, anyl. iMa XE"+Ua[ ME I I I WMR .ILRI,a W wom G[M1 MM MCIW WE f•Ta. IIEYP'f xrDVM .W/ li �`� mr m�tA OFMovo .MS art. rasp. XNPI® sCMYd. AWL Mr r,W N YI MG rMNRMr Se A .,` NSA aX mn1Na DovIc rArS, rX • r' MX lr o„mm a amWaM M w er nrn,eP moY s[rnon AREA INLET FILTER STRAW SALES -_.-NOT Tos[A[. .. ..__ SECTION AT DETENTION POND OUTLET -:--_ -Not tc sc.:-- I I I � v ei w �R.T9 Ml w 1tee3 W tie �� omwc ow, Me aVnq SECTION ACA AT DET MIQN, PM _ -- - - `- Prop ed Sit Fence 51 00--G.�---_ Ed FI-tom_ Wlyf� 4L eaW S[Mn N N MI SECTION S-B AT DETENTION POND _ adTTd sc.0 ..` -- I W r- OVERFLOW SECTION Nbf`10 $CNF�� IIjPF I 6' Crosspari T.O.F. Elevl 5102.5 B - I 1 5 _ T,0 F. Elev _i '5102.7 2 S. 0.3 I V Jq 5'05 I 5 011 5500 h,CP IC A IY 'r SUEC ON.C=C , IAdpcew lhopeTeel eAaaiq Te fta (W MP S.. PU.0.) - ProoeAr euuMen MaMY, E.Ie1Ng OFNnN t:.NlYe aIUMOaR AaIKQM el PrepeRy eoundny ' Lqa pnn)raay Shpes lwnrd 7 Mft'Im SIa a Ll mard Toward Suetnee Ina F,,oey �.q 5 Manrnum FN rda10M (9 2'. Wn -20 %Met. u e�i=m, 'I e, a gam8 nIi✓' S_ I•MwMMI 15 : Ir� R-NHIWIFo ' .. - 60 r,Ia MALE AT @AST a MST PROPERTY BOUNDARIES p }O 9p r S D o 1" - 30' I'M W soMel I f1MContour Interval - 1' \ Existing Curb, 1 Proposed Slit Fence Gutter k Sidew Ik -...._ ' A alu{f 1 Pr y Overflow ��pl I I � r T.O.F. El". , .O.F 0.2 r �• I 100.7 51005 I,SjI 1 rgL�'9 3 -at t-- me ai I-� 11 JProposed SideW _ Culvert (See De 7 Sheet ¢) I _ J 4 e � Detent�an 2.o 40.0 9- + - a Area C, 7.S 1 r I ,\.. Proposed 2' Wide I H5097�75 o e Concrete Pon 3811 +�-7`1 L 10 0 F. fr T.O.F. Elev.= Try i �$1, .7 .I 5103.2 1.0 � Suss s 2,6 T.O.F. ON).= A--' ll D T.O.F. Elev.-�L 9 "��.a - ' 4 - -4` (9^ L 3-3 3.0 1 T.Q.E8 F.lev.r T.O.F. 6evr•i . _ \ 5105.2 a` j 5104.5 r\ 5` 3 8a.3; • 4.5 T.O.F. Elev.- _IF 5106.7 77 NOTE: SITE GRADING OPERATIONS SHALL BE RESTRICTED TO y "W. PLUM STREET - P.U.D" LIMITS. NO GRADING`OPERATIONS SHALL \/ -•\ w /OCCUR ON THE PROPERTIES TO THE WEST Op EAST OP THE .$1T'E. Sidewalk Culvert sad 12'0 N-12 Pipe Outlet �A `an3 . Inletll.•5tructure w Orifice Plate for Release Control SEE OETNL THIS SHEET) A^ yo-- �l I h0 i I 1 Proposed f Sllt Fence 50g9 I D I SjpO _ STORY WATER DETENTION SUMMARY SITE DRNNS TD 'IMPORTATION CANAL' DRAINAGE BASIN CROSS SITE AREA (Including 1/2 or adjacent W, Plum SL)=144,935 sR-ft NEr srrr AREA - 132,959 Sa-FL - 3.05 Acre,* -331 Acre,* HISTORIC 'C' - 0.20 DEVELOPED 'C' - 0.45 HISTORIC '02' - 1.39 c.f.a. CRITERIA BASED DLIETIRON VOLUME - 10,e36 cu.R.* PUN DETENTION VOLUME - 10.937 cu.k* MAXIMUM DEPTH OF DETAINED WATER - 2.25 R O Elevation 5097.50 PEAK DISCHARGE FROM -OL wroH, 0 - 'HISTORIC' 02 + OOPFSfE - 1.92 e.f.R2 RUN-OrF SUMMARY )i(SM Am :z (Acre) e.f.eJ cds. A 0.60 0.45 0.67 1.22 B 0"Se 0.45 0.53 1.51 c 0.40 0.45 0.33 1.06 1 0.56 0.45 0.53 1.75 2 2.73 0.45 3.00 e.97 City of Fort Collins, Colorado _ UTILITY PLAN APPROVAL N N _ APPROVED: rcec or .1 ltF,,rWn%g N CHECKED BY Aors o WT W. v .tt., LIIi MA, y pots CHECKED BY , ormwavr IIy a V p F CHECKED BY 7-.W. - c u n N CHECKED BY' P Q o CHECKED SY'. J ^j F.Li W c 0 far,S1PSnC4 RPIEVC[ W D v OE E m O -Iotm t nut. r- r vn stNgNro me,l c 1LJEV[L 2P K1 oIV lML•F➢ BY IaS518 .�RMe.nc �Rtt ail ) �1 9B. � a U W N w C 9 � ?GR M vW or , W Ili, M SMNS -!C, EAOLON a CL YGS O n .1C 1. It. 'MT:ID. Y�eKJ.TaIr0 .tr .Wno SG6NE IIEgA[ SIIl.1r'r.FG ww ra .1. IFuE an crnAty e Q c O ' 4eRN^�N �+R_I�•ntY+36w, YN'I+uxe•••.Iarlruclw�loerlNwlo[�cI avow, wwo rrosa, co . omet biMNMni. Cn r ,) C 0 N m set, •rwr •' I I C p n ve.. wn- •r.••Ne.•1 � ear nNewNi eeaaN eox,na, W - s+AucruMl. sa rw• e.m... raw ✓' -•�• z ,ST:<rJ,NL r rM PINYp n Q' � O s.•N•'•N ei.iXry r -y-y .� a O Sa O Ti slleRtlwrs: rmNtm M wWrwlm �/ M.1 6 O -___ ar _ _-.. WW U vitt*umMacMc carlMndt __ vrt awn0 4 QWD W or, or rwR caua al__ z , �' ,__ o Q azr, U ns----- T pi Indicates Existing GYound Surface Contour •�,6tao-/ Typically Indicates Proposed Imsh Surface Contour \1a ~ \� Typically Indicates Proposed Curb, Gutter @ Sidewalk H"'4 y �. w - Tr Typially Indicates Existing Curb, Z W Gutcter @ Sidewalk u o_ �E --x-- Typically Indicates 'Silt Fence' DATE MAY IL199e SCALE: AS NEED FJ Typ�1icallyy es Drainage DRAWN: U.S _ FIDW OirECtiOn ection CHND: DRN. Typically Indicates Drainage PLA-195-96 9osin Limit SHEET A Ty ically Indicates Concentration a r y1� Paint Identifier 3 of ,C 6 C-3 1596 G allis o w a y Planning. Architecture. Engineering. ' VARIANCE APPLICATION Stormwater Alternative ComplianceNariance Application _ City of Fort Collins Water Utilities Engineering ' Engineer Name Herman Feissner Phone 970.800.3300 Street Address 5265 Ronald Reagan Boulevard ' .City Johnstown state Colorado Zip 80534 Owner Name High Plains Builders, LLC Phone 307.257.2352 ' Street Address P.O. BOX 2796 _ city. Gillette state Wyoming Zip 82717 ' Project Name Elizabeth Street Farms Project/Application Number from Development Review (i.e. FDP123456) PDP160037 ' Legal description and/or address of property 2620 West Elizabeth Street; Fort Collins, Colorado 80521 ' Description of Project Proposed single-family residential development ' Existing Use (check one): 0 residential Ct non-residential Q mixed -use G) vacant ground Proposed Use (check one): 9 residential ® non-residential C mixed -use 8 other ' If non-residential or mixed use, describe in detail State the requirement from which alternative compliance/variance is sought. (Please include ' applicable Drainage Criteria Manual volume, chapter and section.) ORDINANCE NO. 007, 2016 13.1 Low Impact Development Criteria ' What hardship prevents this site from meeting the requirement? 1) the closest underground storm drain system is located more than one-half mile to the east on ' Elizabeth Street 2) the bore logs show on -site soils that are unsuitable for infiltrating water (i.e., from a rain garden and etc.) Attach separate sheet if necessary ' What alternative is proposed for the site? The proposed project will drain developed lot areas and right-of-way area (private) across ' landscaping (i.e., grass buffer strips) and into vegetated swales. To the Maximum Extent Practicable (MEP), the site will disconnect impervious areas. Attach separate sheet if necessary page 2 The owner agrees to comply with the provisions of the zoning ordinance, building code and all other applicable sections of the City Code, Land Use Code, City Plan and all other laws and ordinances ' affecting the construction and occupancy of the proposed building that are not directly approved by this variance. The owner understands that if this variance is approved, the structure and its occupants may be more susceptible to flood or runoff damage as well as other adverse drainage issues. y- Q� Signature of owner: Date: J 3 1 f 0 The engineer hereby certifies that the above information, along with the reference plans and project descriptions is correct. Signature of engineer: �l`�-----_ ' Date: OS /04) 20i8 38466 4 20 PE STAMP Date complete application submitted: Date of approval/denial: Variance: ❑ approved ❑ denied Staffjustification/notes/conditions: Approved by: Entered in UtilityFile Database? []yes [:]no