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Home My WebLink AboutGrading Plans - 02/06/2020O r- Landmark November 14, 2019 (Revised December 18, 2019 & January 2!, 2020J ` � Project No: STRATH-19H 1 D-28-307 B1903301 DRAINAGE MEMO Permit released 1/9/2020 in Lot 21, Block 274, West Side Addition to Fort Collin advance of minor (a.k.a. 414 North Loomis Avenue), Fort Collins, CO adjustments to plan/memo. Plan/memo accepted To Whom It May Concern, 2/6/2020 DJM The purpose of the grading plan �or the above mentioned address is to protect the proposed structure and adjoining lots from stormwater runof� The existing subdivision (West Side Addition to Fort Collins) was established around approximately 1900 and the grading for the subdivision will never be able to apply to current drainage and grading standards. The lot is confgured as a"Type B" grading which allows for drainage from a high point to both the front and rear o f the lot The existing lot line on the north is fairly flat for the front 67 +/- feet with the rear 123 feet +l- at approximately 0.81 % and the south lot line front 67 feet +l- at approximately 2.09% and the rear 123 feet +l- at approximately 0.81 %. These ore existing established lot lines with an alley running to the rear o f the property. Grades cannot be changed without impacting other residences adjoining the alley. At the request of the City, we have performed run-off calculations for the 10-year and 100-year storm events using the pre-addition to the house that occurred in 2018. Since this lot is "rype a" it has two directions o f drainage. The front drainage is noted as Southwest Basin (SW) and the one to the rear is noted as Southeast Basin (SE). The entire lot consists of 6,913 square feet (sq. ft.) or 0.16 +/- acres. For the SW Basin we used a total area of 1,952 sq. ft. or 0.04 +/- acres. Concrete and roof areas was 820 sq. ft. or 0.02 +l- acres and the lawn area was 1,132 sq. ft. or 0.03 +/- acres. The basin has slopes of 2.0% for 4 feet and 3.40% for 53 fee� The SW Basin did not change f'rom existing to developed. For the existing SE Basin, we used a total area o�' 4,961 sq. �t. or 0.1 1+/- acres. Existing concrete, pergola, and roof areas was 1,083.5 sq. ft. or 0.02 +/- acres and lawn area of 3,877.5 sq. ft. or 0.09 +/- acres. The developed concrete, pergola, and roof area will be 2,238 sq. ft. or 0.05 +/- acres and the lawn area will be 2,723 sq. ft. or 0.06 +/- acres. As stated earlier, the proposed additions do not change the SW Basin drainage and only impacts the SE Basin drainage. We analyzed the existing conditions and proposed conditions (with the addition) to determine the respective runo f�s. We multiplied these run-of�rates by the City 1.25 factor. For the existing and proposed SW Basin, for the 100-year storm, the run-of f�was calculated to be 0.32 cubic feet per second (c.f.'s.). For the SE Basin, for the I DO-year storm, the run-off' was calculated to be 0.58 c.f:s. Adding the proposed additional impervious area, the SE Basin, for the 100-year storm, the run-of� was calculated to be 0.64 c.f:s. Therefore, the additional run-of� would be 0.06 c. f.s. We have attached copies of the analysis to the report to document the run-of�values listed above. The proposed top o f foundation o f the new garage structure, was set to have a minimum o f 6" o f foundation reveal and an approximate !0% grade to the nearest lot line to the north with an approximate elevation of 5,002.70. The proposed garage in roughly the same location as the old garoge and the drainage pntterns that existed for the old garage should be maintained for the new garage. The runo(f from the rear o f the yard should flow to the alley as it has done historically. Stratton Homes 414 N. LoomisAvenue Landmark Project No. STRATH-19HID-28-307 December 18, 2019 (Revised December 18, 2019 & January 2 l, 2020) � Therefore, the Top of Foundation elevation was set at 5,003.90. The old garage also had an old concrete drive that will be replaced with a new concrete drive. A site visit determined the alley at the rear of the property is slightly crowned at the south lot line with the crown disappearing about half way down the olley. However, the alley is at a slope of 2.7+% which is greater than most of the existing slopes in the area and therefore, should not be an issue. The alley and grades are shown on the attached Revised Plot Plon and the additional developed run-o f� will flow down the alley towards Cherry Street as has historically occurred should not be an impact on the area drainage. In addition, final grade spot elevations have been provided along the edges of the garage driveway, as requested by the City of Fort Collins staf� to direct the driveway flows to the alley. The minor increase in impervious area and the corresponding miniscule increased run-o f� in e f�ect, will not change the historic drainage of the surrounding alley and properties and insure the site drainage will not impact the proposed structure or adjacent properties. Stormwater runo f� will flow around the proposed structure on either side and will reach the street or the alley as historically has occurred and flow to the respective curb and gutter flowlines. The top of foundation, adjacent finish grades, and spot grodes and elevations shown on the PJot Plan/Grading Plan and the in formation in this memo should be used to perform the fnal grading for the site. l�'you have any questions, please feel free to contact our o f f ice. Sincerely, LANDMARK ENGINEERING, LTD. � �l Rodney . Harr, P.E Direcior of Engineering attachements ,.;;��i!.�;:r�, ;�`•` i, n � �'' c �. � � , __ - l� �/�; _�\`� �.. •° , -:, .,� -.... • ' - �� ro�y ' �� /' •� (� Iti i'��L ;' �.t�� JII'Il1f�'��` PLOT PLAN LOT 21, BLOCK 274, WEST SIDE ADDITION TO THE CITY OF FORT COLLINS 414 NORTH LOOMIS AVE., FORT COLLINS, COLORAD�I I EC=00.00 - EXISTING GRADING Fc I V L O O M I S A V E �� T.O. F- TOP OF FOUNDATION sOo, c°o F.G.- AfINIMUM DIRT FINISH GRADE NEXT TO FOUNDATION �s� NO' 26� 47��W 35.00�1� SLAb=00.00 - TOP OF CONCRETE SLAB � � � E � 0 0 z n � i U � Y a s r � o�c�c��w��c��vo ��a��'�oy��b�� ,r \� 2.�b�y��i��2�� y�� i��kCs�y� �yay�p �y0'��"�`'�Uy�� Zby'y � �� C+�n ��C.,�,��tt�b�'n�l U70�0� �'�o�tx�o��o�b� �0��"� n �f b�C�7a4 y� ��c�� b��''7yo��h aZ�hs �1 �7�'��„na y ��n �a� �] � � � � � �S�b�2:�Cv�hb r'�a�o yy�� y ~ y �� hc�j� O� O��"�C � y�Y� �Z`Co �� ob��i � �� a�y � b�b � v�o� �C� ��~ � �yti �a�� bZ � �b� N�oC �� a�s o �� b2 �� y��i� '� � o L�j�ib `t�1�` ''��b `j o�ti ��y O� �� k�b ah� 'n� �o��i �i �� z��,o�� x y�zo � �mm � a � � �� h� b'�� C��C� �a � � y�� ai ��o �° � �� o�o a �o � n � n� �y��' � C�' � C a �y ��o o �y `� �, o � „�'t � y� ``N�� y y� a O �] � � VJ � �.tl � 'y U7 O � � ' �C' O b � � �y�� b � � �' � �� `� y y � a � �Z C �� b � � o t�� b b � � 0 � m a � y � � `��e o n � 2.7% LOT 21, 6,913 SQ FT � � � cD Z � c,� �O c,� '� � . II 2 X C,� (� �� „m� c,i � m � P� �.�o •4 e 1 � � om �� II � �o o� ��►��7� 1 cP m x � �N � � Z � D� � 1 NO' 26� 47'� PROPOSED �� ADDITION 8.49'\ d' Fc�, '� 0 16.00' 2soosOgB / .00 6090' Ni o � �sa. + 23.00' � Ul � � c�, CJ� (� o "_ 0 c� � 12.50'` DRIVEWAY � 1 cD 0 0 7.00' o �ri .00' 2.U� ALLEYWAY TO CHERRY STREET � = LANDMARK ENGINEERING LTD. � 3521 WEST EISENHOWER ; LOVELAND CO 80537 � PHONE (970)667-6286 e www.landmarkltd.com N � F� m M 1.47 �b2 cn x n� ry} O Z N .5 � .�50° � c� SO' 26' 47"E 42. cueNr: STRATTON HOMES nnF: PLOT PLAN �A�:1 /21 /2020 ISc�: 1 "=20' JOB "° STRA-18-05-032 Area-Weighting for Runoff Coefficient Calculation Project Title: 414 N. LOOMIS FORT COLLINS Catchment ID: SW -- p�r�, �f -,-; -;� ' �l �.�E Illustration Instructions: For each catchment subarea, enter values for A and C. Subarea Area Runoff Product ID acres Coeff. A C` CA input input input out ut 0.02 90.00 1.80 0.02 2.00 0.04 Sum: 0.04 Sum: 1.84 EC�TiD: Low Uirectian C�t�� mt Satm.dary Area-Weighted Runoff Coefficient (sum CA/sum A) = 46.00 `See sheet "Design Info" for inperviousness-based runoff ccefficient values. UD-Rational v1.02a, Weighted C 12/16/2019, 10:28 AM CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title: 41� N. LOONlIS FORT COLLINS Catchment ID: SW I. Catchment Hydrologic Data Catchment ID = SW Area = 0.04 Acres Percent Imperviousness = 46.00 °� NRCS Soil Type = C A, 8, C, or D II. RaiMall Information 1(incfUhr) = C1 • P1 1(C2 + Td)"C3 Design Stwm Retum Period, Tr = 10 years (input retum period for design storm) C1 = 28.50 (input the value of C1) C2= 10.00 (input the value of C2) C3= 0.786 (input the value of C3) P1= 1.40 inches (input one-hr preapitaHon—see Sheet "Design Info'� III. Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Coefficierri, C = 0.44 Overide Runoff Coeffiaent, C= (enter an overide C value if desirEd, or leave blank to accept calculated C.) ryr. Runoff CoeSicient, G5 = 0.38 Overide 5-yr. Runoff Cceific�ient, C= (enter an overide C-5 value "rf desired, or leave blank to accept calculated C-5.} Illustration Calculations: Reach Slope Length ID S L ftlft ft input input Ove�iand 0.0200 4 1 0.0340 53 2 3 4 5 5-yr NRCS Runoff Co�vey- Coeff ance C-5 0.38 � rllA 7.00 Flow Fbw Velodty Time V Tf fps minutes a�inut ouhwt 0.03 2.08 0.68 computea 1 c = 1. /ti Regional Tc = 10.32 User-Entered Tc = 5.00 IV. Peak Runoff Prediction Rainfall Intensiry at Computed Tc, I= 5.39 inchJhr Rainfall Intens'Ry at Regional Tc, I= 3.74 incfi/hr Rainfall Intensity at User-Defined Tc, I= 4.75 inch/hr Peak Flowrate, Qp = 0.09 cfs Peak Flowrate, Qp = 0.07 cfs Peak Flowrate, Qp = 0.08 cfs UaRatianal v1.02a, Tc and PeakQ 12116/2019, 10:28 AM CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project T'rtle: 414 N. LOOMIS FORT COLLINS Catchment ID: gW I. Catchment Hydrologic Data Catchment ID = SW Area = 0.04 Acres Percent Impenriousness = 46.00 % NRCS Soil Type = C A, B, G or D II. Reirrtall Information I(inch/hr) = C1 " P1 /(C2 + Td)"C3 Design Stortn Retum Period, Tr = 100 years (input retum period for design stoRn} C1 = 28.50 (input ihe value of C1) C2= 10.00 (input the value of C2) C3= 0.786 (input the value of C3) P1= 2.83 inches (input one-hr precipitation—see Sheet "Design Info'� III. Analysis of Flow Time (Time of Conce�tration) for a Catchment Runoff Ccefficient, C = 0.59 Overide Runoff Ccefficient, C= (enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 = 0.38 Overide 5-yr. Runoff Ccefficient, C= (enter an overide C-5 value ff desired, or leave blank to accept calculated C-5.) Illustration Calculations: Reach Slope LengM ID S L ft!ft ft inout inout Overland 0.0200 4 1 0.034d 53 2 3 4 5 Sum 57 IV. Peak Runoff Prediction Rainfall lntensity at Computed Tc, I= 10.90 inch/hr Rainfall Intensity at Regional Tc, I= 7.56 inch/hr Rainfall Intensity at User-Defined Tc, I= 9.60 inchfi� EXISTING SW 1aYR, Tc and PeakQ 5-yr NRCS Flow Runoff Convey- Veloaty Cceff ance V C-s fps outDut input output 0.38 WA 0.03 7.00 1.29 Computed Tc Regional Tc User-Entered Tc Flow Time Tf minutes [:�:3 10.32 5.00 Peak Flowrate, Qp = 0.26 cfs Peak Flowrate, Qp = 0.18 cfs Peak Flowrate, Qp = 023 cfs D, 2� �►. z 5= p. 3Z G�s�S 12116l2019, 10:31 AM Area-Weighting for Runoff Coefficient Calculation Project Title: 414 N. LOOMIS FORT COLLINS Catchment ID: EXISTING SE illustration Instructions: For each catchment subarea, enter values for A and C. Subarea Area Runoff Product ID acres Coeff. A C" CA input input input output 0.01 90.d0 0.90 0.09 2.00 0.18 Sum: 0.10 Sum: 1.08 EC�IVD: Low Directian G�� Bot�nQxy Area-Weighted Runoff Cosfficient (sum CAlsum A) = 10.80 'See sheet "Design Info" for inperviousness-based runoff ccefficient values. EXISTING SE 10-YR, Weighted C 12/16l2019, 10:56 AM CALCl1LATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title: 414 N. LOOMIS FORT COLLINS Catchment ID: EXISTING SE I. Catchment Hydrologic Oata Catchment ID = SE Area = 0.10 Acres Percent Imperviousness = 10.80 % NRCS Soil Type = C A, B, C, or D II. Rainfall Information I(inch/hr) = C1 ` P1 /(C2 + Td)"C3 Design Storm Retum Period, Tr = 10 years (input retum period for design storm) C1 = 28.50 (input the value of C1) C2= 10.00 (input the value of C2) C3= OJ86 (input the value of C3) P1= 1.4a inches (input one-hr precipitation—see Sheet "Design Info") III. Analysis of Flow Time (Time of Concentration) for a Catchment Runoff Ccefficierrt, C = 0.31 Overide Runoff Coefficient, C= (enter an overide C value if desired, or leave blank to accept calculated C.) 5-yr. Runoff Coefficient, C-5 = 0.21 Overide 5-yr. Runoff Ccefficient, C= (enter an overide C-5 value 'rf desired, or leave blank to accept calculated C-5.) Illustration Reach 2 �� i� /�Rcaeh 3 k NRCS Land Heavy Til[agel Type Meadaw Field Ccnveyance 2.5 C Calculations: Reach Slope ID S it/ft inpUt Overland 0.0200 � o.00sz 2 3 4 5 IV. Peak Runoff Prediction Rainfall Intensity at Computed Tc, I= Rainfall Intensity at Regional Tc, I= Rainfall Intensity at User-Defined Tc, I= ; BeaecA 1 Short Nearly Pasturel Bare Lawns Ground � 10 Length L ft input 4 171 5-yr Runoff Coeff G5 Suml 175 4.30 inch/hr 3.65 inchmr 4.30 inch/hr averlud �GF1VD 8ow �� F7e�r Diiscti� �— Caiel�tiewt Be�r� G.�assed Paved Areas � Swales! Shallow Paved Swales Waterw tSheet FIow1 15 20 NRCS Flow Flow Convey- Velocity Time ance V Tf ips minutes inout outAut ou�ut 1 N/A 0.03 2.54 7.00 0.63 1 4.50 Computed Tc =� Regional Tc = 10.97 User-Entered Tc = 7.04 Peak Flowrate, Qp = 0.13 cfs Peak Flowrate, Qp = 0.11 cfs Peak Flowrate, Qp = 0.13 cfs EXISTING SE 10-YR, Tc and PeakQ 12/1612019, 10:58 AM CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title: 414 N. LOOMIS FORT COLLINS Catchment ID: EXISTING SE I. CatchmeM Hydrologic Data Catchment ID = SE Area = 0.10 Acres Percent Imperviousness = 10.80 % NRCS Soil Type = C A, B, C, or D II. Rainfall Information I(inchlhr) = C1 ` P� /(C2 + Td)"C3 Design Storm Return Period, Tr = 100 years (input retum period for design stortn) C1 = 28.50 (input the value of C1) C2= 10.00 (input the value of C2) C3= 0.786 (input the value of C3) P1= 2.83 inches (input one-hr precipitation—see Sheet "Design Info'� III. Malysis of Flow Time (Time of Concentration) for a Catchmerrt Runoff CceSicient, C = 0.53 Overide Runoff Ccefficient, C= (enter an overide C value "rf desired, or leave blank to accept calculated C.) ryr. Runoff CoefficieM, G5 = 0.21 Overide ryr. Runoff Coefficient, C= (enter an overide C-5 value if desired, or leave blank to accept calculated C-5.) Illustration � �aerla�d �� j' Reui 1 tl� Beu12 � f7wr Diiecti� / r r.�.,...�+ Bc�eh 3 Bo� t CalculaGons: Reach Slope Length ID S L ft/ft ft inDut input Overland 0.0200 4 1 0.00$2 171 2 3 4 5 Sum 175 IV. Peak Runoff Prediction Rainfall Intensity at Compu[ed Tc, I= 8.68 inch/hr Rainfall Intensity at Regional Tc, I= 7.38 inch/hr Rainfall Intensity at User-Defined Tc, I= 8.68 inchlhr EXISTING SE 10aYR, Tc and PeakQ Syr NRCS Flow Flow Runoff Convey- Veloaty Time Coeff ance V Tf C-5 fps minutes output input output WJ�I[ oz� w,a o.os 2.5a 7.00 0.63 4.50 Computed Tc = 7.04 Regional Tc = 10.97 User-Entered Tc = 7.04 Peak Flowrate, Qp = 0.46 cfs Peak Flowrate, Qp = 0.39 cFs Peak Flowrate, Qp = 0.46 cfs 0.�[� � �.z5=� �.5g �,�s 12/16/2019, 1122 AM PLOT PLAN LOT 21, BLOCK 274, WEST SIDE ADDITION TO THE CITY OF FORT COLLINS 414 NORTH LOOMIS AVE.> FORT COLLINS, COLORADQ, , LOOM I S AVE EC=00.00 - EXISTING GRADING c IV T.O. F- TOP OF FOUNDATION ��, .�,� F.G.- NINIAfUA( DIRT FINISH GRADE NEXT TO FDUNDATION si NO' Z6� 47��W 35.00�.• SLAB=00.00 - TOP OF CONCRETE SLAB � ' o caC��mcn ��dawo�vac�o � � �� o �Z�C�a��yx�bob�� ''�'t�i��t�ia o�.��'��n\� ITEM ��y�'O�y�'~�� io Cs � b o v�oh b �yby�[�i�ti�'��'o� o��,.��y Frontwalk � Z�t�na� ~b�n ��2yy Cb„ Frontporch �i ,.r'�� v�o ��ioo a House � � bo�n�o� �'ab� o� v�,y� Rearpatio ��x�'�'� oZa�' � a�� Reazstoop yb�� ba�s 2a Reazwalk h � ��Za y��nh � br'� Addition o � „�� `t � � � � � � � Pergola �oob' �� ,��h� b ��O Gazage y y � � � y � y tp � �3 � � � Conc. �ive ��y� ��, y�� '' �h,�,y Total ��^�C� �s `��b�� yn� Delta � y�� N '�a�a � ^c�O � p�'O� �Q1 'y�hy'J„' t�, py+y. %IIDp- � ya�� b� y bo o a `� y w a�i � � t� �� Delta N��C �� b�oy o ~�� b� � ��iZ '=7 'l� O LOT 21, 6,913 SQ FT Existing Proposed SQ. FT. SQ. FT. 80 80 iso iso � ] 004.5 1004.5 N � r 192 0 � 25 0 W rn � 208 0 c.,� � �, r,, 0 767.5 � n p x 112 112 W o c� 268 268 � c�n m z 64 64 i; " 225 225 ' 2328.5 2671.1�� ' +342.5 S�o, 33.68% 38.64% +4.95% z � co rn rn W 0o W w f*I �� y •4 � U I c�+ � 7.25' � o � D � �� A N r� v' � O n� O 00� o 0 O pZ� O N � �o � N �a�° by �-ae ° y �� yo�� s� �'��' � �,�Zib � � 'y y �. � � la� �] �7 b�`� ,�� o�� VJ yt�b t\vo�� a,` C C�W a ��o ,b �rh•bi '-n3 Ccaj � � � � i`�� i]�� C� l'�e�� a] � � � a� �C�b � �~ � �� b �� oa-�e.�b � y,�b� n � c�'�i by"• � �� C � �� 02�� y�o � n caj� ��'0 �i �� +7 � y �a�� o � � ��C p �� O t�] tba� a y � � � � � �'J � S O ''� x (a� `i � C a C�� c �� b � d ��„r'Sa s ya8 � m � b� `o o� � � y� b � � Cn m X U �N � O Z � D� � rn w � � I 15.62' I6.0 13.32' � . : N 0' 26' 47•• W tiooy' 7.50' 6� � 26g � �m � DX D � C"' m z W � W � m � _ �n W �� r �Z❑ � � oo� � � 4� V � � SO' 26' 47"E 42.50' cuo+r. STRATTON HOMES � �"� � PLOT PLAN �xr5� � «.�.�. �..: � � ` � 0:870-le6�nT DAIE SCALE: �-�-`�� 06/05/2018 1 "=20' w srod.n.,ds„� ,ioe "o- STRA-18—OS-032 � Area-Weighting for Runoff Coefficient Calculation Project Title: 414 N. LOOMIS FORT COLLINS Catchment ID: DEVELOPED SE Illustration Instructions: For each catchment subarea, enter values for A and C. Subarea Area Runoff Product ID acres Coeff. A C' CA input input input output 0.04 90.00 3.60 0.06 2.00 0.12 sum: 0.10 Sum: 3.72 EC�TTTD: law DirecCian Catc�m e� �rn�ndacy Area-Weighted Runoff Coefficient (sum CA/sum A) = 37.20 'See sheet "Design Info" for inperviousness-based runoff coefficient values. DEVELOPED SE 10-YR, Weighted C 12I1612019, 10:54 AM CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD Project Title: 414 N. LOOMIS FORT COLLINS Catchment ID: DEVELOPED SE I. Catchment Hydrologic Data Catchment ID = SE Area = 0.10 Acres Percent Imperviousness = 37.20 °k NRCS Sail Type = C A, B, C, w D II. Rainfall Information 1(inchlh�) = C1 ` P7 /(C2 + Td)"C3 Design Stortn Retum Penod, Tr = 10 years (input retum period for design storm) C1 = 28.50 (input the value of C1} C2= 10.00 (input ihe value of C2) C3= 0.786 (input the value of C3) P1= 1.40 inches (input one-hr preapitation—see Sheet "Design Info'� III. Analysis of Flow Time (Time of Concentra6on) for a Catchment Runoff Coefficient, C = 0.41 Overide Runoff Coefficient, C= (enter an overide C value if desired, or leave blank to accept calculated C.) ryr. Runoff Coeffiaent, G5 = 0.34 Overide ryr. Runoff Coefficient, C= (enter an overide �5 value if desired, or leave blank to accept calculated C-5.) Illustradon Calculations: I Re�ch Slope I Length ii1�li�� Ove�land I 0.0200 4 1 0.0082 171 2 3 4 175 IV. Peak Runoff Prediction Rainfall Intensity at Computed Tc, I= 4.37 inch/hr Rainfall Intensity at Regio�al Tc, I= 3.65 inch/hr Rainfall Intensity at User-Defined Tc, I= 4.37 inch/fir �yr NRCS Flav Flow Runoff Convey- Velocity Time Cceff ance V Tf C-5 fps minutes out[Tut input output ou��t 0.34 N/A � 0.03 2.19 7.00 0.63 4.50 Computed Tc = 6.69 Regional Tc = 10.97 User-Entered Tc = 6.69 Peak Flowrate, Qp = 0.18 cis Peak Flowrate, Qp = 0.15 cFs Peak Flowrate, Qp = 0.18 cfs DEVELOPEO SE 10-YR, Tc and PeakQ 12/16/2019, 11:11 AM CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD P�oject Title: 414 N. LOOMIS FORT COLLINS Catchment ID: DEVELOPED SE I. Catchment Hydrologic Data Catchment ID = SE Area = 0.10 Acres Percent Imperviousness = 37.20 °� NRCS Sal Type = C A, 6, C, or D 11. RaiMall Infortnation I(inch/hr) = C1 • P1 !(C2 + Td}"C3 Design Storm Retum Period, Tr = 100 years (input retum period for design storm) C1 = 28.50 (input the value of C1) C2= 10.00 (input the value of C2) C3= 0_786 (input the value of C3) P1= 2.83 inches (input one-hr precipitation—see Sheet "Design Info") III. AnaFysis of Flow Time (Time of Concentra6on} for a Catchment Runoff Ccefficient, C = 0.58 Overide Runoff Coefficient, C= (enter an overide C value if desired, or feave blank to accept cala�lated C.) �yr. Runoff Coefficient, G5 = 0.34 Overide ryr. Runoff Coefficient, C= (enter an overide C-5 value if desired, or leave blank to accept calculated G5.) Illustration Calculations: Reach Slope Length ID S L fl/ft ft inDut input Overland 0.0200 4 1 � 0.0082 171 2 3 4 5 Sum 175 IV. Peak Runoff Prediction Rainfall Intensity at Compu[ed Tc, I= 8.83 inch/hr Rainfall Intensiry at Regional Tc, I= 7.38 inch/hr Rainfall Intensity at User-Defined Tc, I= 8.83 inch/hr DEVELOPED SE 100-YR, Tc and PeakQ 5-yr NRCS Flow Flow Runoff Convey- Velocily Time Coeff ance V Tf C5 fps minutes output input outout outvul 0.34 N/A 0.03 2.19 7.00 0.63 4.50 Computed Tc = 6.69 Regional Tc = 10.97 User-Entered Tc = 6.69 Peak Flowrate, Qp = 0.51 cfs Peak Flowrate, Qp = 0.43 cfs Peak Flowrate, Qp = 0.51 cfs a,5( � I-z�S= D• ��4 C�S 12H6/2019, 11:12 AM PLOT PLAN LOT 21, BLOCK 274, WEST SIDE ADDITION TO THE ClTY OF FORT COLLINS 414 NORTH LOOMIS AVE., FORT COLLINS, COLORADO L�00.00 - EXISTING CRADING F� N L 0 0 M I S A VE �� T.O.F - TOP OF FOUlIIDATION �� S F.G.- Yl7JIMiY DIRT FINISH GRADE NEXT TO FOUNDATION �� N0� 26� 47'�W 35.00�1+ SLdB=00.00 - TOP OF CONCRETE SLdB 1 � LOT 21, NOTES: G, 913 SQ FT f. THIS PLOT PLAN IS BASED ON INFORYdTlOX PROVIDED BY THE O)YNER/CONTRAClOR THE OA'NER/CONTRACfOR SHALL VERIFY ALL LOT DIJ/ENSIONS, SETBACK INFOiWATlON, BASEYENT IIlDTHS, GRADING ELEVATIONS dXD TfIE PROXIYITY TO EXISTING STRUCTURES �'ITX TXE COVI�RNTNC AUTNORITY AND OR COVENANfS. 2. DIYENSIONS SAO)IN dROUHD THE PERIYETER OF TIIE V► STRUCTURE 1RB TO EXTBRlOR FOUJVDATION CORNERS. 0° cO 8. THE CONTRACTOR SHALL VERIFY EI.EVATIONS AND DIYENSIONS PRIOR TO CONSTRUCTION. ANY VARIATlON TO THIS � PLAN SHALL BE READRT�D TD SNYDBR LAND SURVEYING I1VC IYlfSD1ATELY. � 4. PROVIDE AND YAINTAIX ADSITIVfi DRAINAGB AIfAY FROY G! ALL FOUNDATION lI.lLLS: A YINIYUY SLOPB OF !OX IS � REQUIR6D FOR THE FIRST f0 FE�7' AXD THEN A YINIJ(UY SLOPE OF ,2'R IS RSQUIRED THEREAFTER 5. THE YAXIYUY DRIYE1fAY IIIDTX 5BALL BE SO' A'ITHIN F THE RICf1T OF IIAY. 6. ANY QUBSTIONS OR COAICERNS CONCSRNIIVC TXIS PLOT �.to PLAN PLEASB CONTACT SIVYDBR LAND SURVEYING INC. ! IYXBDIAT%LY. 7. DUE 71U TXE LACX OF PROP�RTY G1�RNERS FOUND, IT IS REL^OYYL�'NDED A COYPL67E BOUIVDARY SURVEY B� DONE !N ORDER TO EXACTLY SH01I PROPERTY LINES. B. INFORYATION FOR TXIS PLOT PLAN IYAS TAXEN PROY A TOA7GRAPHIC SURVEY COYPLET�D BY NOI{THERN ENGINEBRING PROJh�CT NUY9ER 1f0-072, DATED f0/2I/2017. ITEY EXISTING SQ. FT. PROPOSSD SQ. 1�'T. ARONT IYALK 80 80 FRONT PYJRCX f60 150 HOUSE 1772 f772 PERCOLA 112 1f2 OLD GARACE 268 0 NEII GARAGE 0 328.5 SHED 6� 6� OLD CONC DRIVE 225 0 NEIY CONC DRIVE 0 556. S t387.0 TOTAL 267f.0 3058.0 X7YPERVIOUS. 38.6�76 t�.249: DSLTA t5.60% � � �� .1 �' s '� m � NCN � N m z ,�"� � i" � 1 1 � �� \ bm �� ir O° o� o �" :P` V O � 0 � CT r�i X cn � �,_. O o ��- o rZ�. D � NO' 26' 47"W 7. 50' . �, c.+ ' W W NORTH � c,� ! tr � 2� 4�� i O QDS = DOWN SPOUT DIRECTION •�ti°� � �,c?�. LANDMARK ENGINEERING LTD. 3521 YlEST EISENHOWER BLVD. LOVELANO CQ 80537 " ' � �"" ' �HoriF (s�o)ss�—s2ss `,`10 Rf ;,, �:; -. www.landmarkltd.com '"• .,i � `.Ci�/<�f,�! ��' r- {� - �� ` ��; � .� ��. NAl "�;. .' ' �O 7� 0 � PROPOSED ADDI�ION � � a 16.0' - �o �; : � �� ; F.F. = 5003.90' 12.5' '�6 � / DRIVEWAY � � cD W w w rri �� . � T a � � �� , o � � ` 0 � �- � m � �� i �n 6cJ. vZ � f�2� SO' 26' 47"E 42.50' C1EHT: STRATTON HOMES n'� PLOT PLAN DAlE 11 /14/2019 Dwelo� � 1 "=20' � SNYDEL-19H1 D-28-307