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Home My WebLink AboutGrading Plans - 04/06/2017Approved 4/6/2017 - WL INORTHERN ENGINEERING Water Utilities Engineering 700 Wood Street Fort Collins, Colorado 80522 Re: 305 Circle Drive Redevelopment Drainage Evaluation Dear Staff: March 28, 2017 The owners of the residence at 305 Circle Drive in Fort Collins would like to reconstruct the home onto their property for personal use. Building permit plans are being submitted to the City for approval. It was requested of us to provide a grading plan for the home and evaluate the change in drainage from the property. The property falls within the Spring Creek Master Drainage Basin. The property resides within the Circle Drive Subdivision, platted in 1945 by Northern Colorado Loan Association. Currently, this property is developed as a single-family residence. The subdivision would have been developed under the criteria in place at the time of platting. Any effect of updates to drainage criteria would be recognized by the Spring Creek Master Drainage Plan and should not affect the vested rights of property ownership. It is our understanding that runoff to neighboring properties cannot increase in rate however nominal increases in imperviousness are allowable with redevelopment of single-family uses provided they drain to adjacent streets. We are providing a grading plan that reduces runoff to neighboring alleyways and adjacent lots. According to the attached calculations, the overall lot impervious area is increased by approximately 850-sf. The area draining to the alley is reduced by approximately 1,100-sf. The property as proposed, including the adjacent roadway is calculated to be 44% impervious. We have attached the impervious calculations for your reference. We trust that this letter will satisfy the requirement for evaluation showing that the proposed expansion is within impervious limits used for drainage design within the City. Please contact Northern Engineering with any questions or concerns regarding this matter. Sincere " N r �'�.�.��, g _ F �_ r; � �, .� _� �39 q � z: � .� .�.�3�Z��i�� d � , � �, J�'� .� � ___ _. ��vf `�r` ,ti ,� � o N n� �.Y�� Ryan Banning, P.E. Project Manager FORT COLLINS: 301 North Howes Street, Suite 100, 80521 � 970.221.4158 GREELEY: 820 S`h Street, 80631 � 970.395.9880 � WEB: www.northernengineering.com �NORTHERN Russell Residence E N G I N E E R I N G 305 Circle Drive COMPOSITE % IMPERV/OUSNESS AND RUNOFF COEFFICIENT CALCULAT/ONS 1 Runoff Percentage CHARACTER OF SURFACE : Coefficient Impervious Project: 305 Circle DR Streets, Parking Lots, Roofs, A//eys, and Drives: Calculations By: M. Ruebel Asphalt ................................................................................ 0.95 100% Date: March 28, 2017 Concrete.............................................................................. 0.95 90% Gravel ................................................................................. 0.50 40% Total Lot Area Roofs................................................................................. 0.95 90% 0.24 Acres General Single Family ............................................................. 0.60 50% Lawns and Landscaping Sandy Soil Flat<2% ......................................................................... 0.10 0% Average 2% to 7% ............................................................. 0.15 0% Steep> 7% ....................................................................... 0.20 0% Clayey Soil Fiat<2% ......................................................................... 0.20 0% Average 2% to 7% ............................................................. 0.25 0% Steep > 7% ....................................................................... 0.35 0% 2-year C, = 1.00 0-year C, = 1.0�00-year C, = 1.25 Runoff Coefficients are taken from the Fort Collins Stormwater Criteria Manual, Table RO-11 Composite Runoff Coefficient with Adjustment Area of Area of Area of Area of Area of 2-year 10-year 100-year Basin Area Soil Type and Lawns and Composite Composite Composite Basin ID Concrete Gravel Roofs Single Family Composite Imperv. (s.f.) �sq ft) (sq ft) (sq ft) (sq ft) Average Slope Landscaping Runoff Runoff Runoff % Imperv. Area (sqft) (sq ft) Coefficient Coefficient Coefficient Existing Site IC'� � 1 1_;;� � ; �-i � �� ,zy � Fiar =�� 6328 0.51 0.51 0.63 37% 390A�.57 Proposed Site 1'; ' �y � �iat -:- 5393 0.57 0.57 OJ1 44% 4745.27 Existing to Alley � i��'� � � � i � nat <z°� 3273 0.52 0.52 0.65 38% 2151.83 Proposed to Alley -,. ,,,,y �,�i�r ?^�. 3225 0.40 0.40 0.50 24% 1054.48 3/28/2017 3:45 PM IlbroncoslengineerslProjects11273-0021DrainagelHydrology11273-002_Proposed Rational Calcs Single-Fami/y MCR.x/sxlComposite RunoffCoefficient N�.ts � � � �� F zm e � � �3 5.�8 r. �rAo� , P�� . 2000�- - . _ A3�� ,.,ks�a- - I _J . i ` '� _ � ,��. � �� , � h� I t= � - � {. � �. I / : � I , �—ee- r % - ;, r r \' A �= � ;� � �� Jjt _ �'j'-_ .. \� � , _.. __ _ ' - -- -- - " � � �- , ittc�� E w .rr;,�sR � �, � F,,,a„ I I ", v� ---�'� —� � � � ,, .>> > ..�..�v, �,�� .�� ' � o�a�� (,' . l i i ii� _ � � i - �� - �� uc� � , �� ,, � ,;;� , �� ;�, �� ,�� , � �, `' � � � ' 5 � ;i F.a,,, I I, '� I t i' I '� ; I 1 �'��I � �� ,5.�� i � i �ni� � `�� I � �; �, _ � I� � �'; , 1 — ii � � �'' I —8.92 I I _ � � � / % y �— � I �� i°, _ , - =c�,a � ' I - _ - -__- _ _ � ��ss '�9 � i I i - � � - ��.< � NORTH 6� > LEGEND � __ �y� f o . , . . `� b�-`�.:z � A. ess ... �eovo�E� w .ae � � Z c� _- . . c a — ., — =w � � z � ---- �� zw .-.�.aFF,��o,.o� oa��aA��r��„��, . � �RA�E�F�.n� _ � �N�=S=.�.� • � - E �r� � NOTES �, ,�_ r �.. � � �o J ��n, �,��o- � 2 ' L �mw. oi � rc��Call�eoror<ya�a'y � � �a��..w,p.��c � City of Fort Collins, Colorado UTILTY PLAN APPROVAL � �:� �:� �� :� �� ' �� sneei �' � ,�� ;� G 1 �: � �� TOPOGRAPHIC SUR VEY Of305 CIRLCEDRIVE, FORT COLLINS ... ��—x--�t---�--w_x—� __"'_ - ,t. '»° oARFA�.s �a. CRAWIN TO' .. . �' �1Ai7ER�k�� I �TREET - -'- . 5 � - I ��. . . $ i �j �_ �� E -�„��„� .o� i � � �° I _ ��.�6a,o- �o '��m.9�,.s, ° v �xis-iNc �zea - � I DRA!NING TO � � a - ,��, ALLEv ` sos ua�.e uu �� \ "5 ��cas s R s . ��''�' � e4icK/ o � ioir�c �i�/�� ' NO HA�MF�±Ii r/ ,� I V �/ icrc�anno- ' � . _ s�LFl aa�� r 1 ninRE o` � � \ — — - � o� Fl AL1EY l� T � 0 � � '�-: . ° �p�..E��iN f'EEI' Y t' = to' ES— �o�a uH[ m'[�[vxorc ceo�srn� iY � sYUVor� .— h�mianc uxe ■ ouuo xs REeu+ Mr�v --ea�.-- oHE roor .crvrwr+ p ca+mo� cax. o°��ea;.'.`»,'-o� sW,��Us. <o��R � �,nKR a =��;,«�� «E�. .sas,�3 HORZO�t TP� �nR�N� P>SFI: ��u'NIIRIF. WS NUW xEMtlPN� e](TOt�) �>1UM, xOR¢OMu COrimOl NO"'I _ ccptuiun !s, Svn.E nl o.99ulf]31A(:.0002tia'rs)T�Ho�t ThIE oRi(.Pi o.o. _ ?wS �rvreAsccnon Morvuuerv*z allo sccnan roRucas orsnms[� "o ;� ding to Ctoiatla law you m nce o.cy legal o a�y a y w eey�a,_ y��i «a�re mav ��y a^ r n�r«i tl� m�: `�v efe ,,:ee m� e woo ie��rear:�i�am�in e�te a� me certitica:ion zM1own .�ereonr (�5��00 tC5 C.u.S. 20t2J w-m-xon Oie08R)-A TOF LI'�10' a�w aTJJ :¢a�m e�r�. nl cc x � � c � �j � � � — � _ � � r zQ � — A A � r � � � � [ . J i L � N 1� O � � 00 f�/) � x a :J U�� -g>�� d < >�i � o� o a"� c. � zmaoe2�-� �,�1 � , � � � � � 0 N N � /�1 . • • �•�� .�♦� :.:♦� �•�♦� �:�=� ►�►�� ►j►j� ►�►�� ►.►� �� Retaining Screws at C 4'-0" or as Directed B Detached Sidewalk PLAN VIEW X (Varies, See Plans � Xmax=2.0') � I 6" SECTION B-B Attached Sidewalk C 5/8" Rolled Steel Tread Plate (diamond pattern) Dimension Variable Notes: I 1. Length of steel plate varies. 2. Chase and cover plate run from Right of Way line to flow line unless approved by the Engineer. With curb walk, cover plate extends from property line to top of walk face. L= 1 1/4" x 1 1/4" x 1/4" C �T �� ° 5/8" Rolled Steel Tread Plate _ 1/2" x 1" Flat Head Mach. Screw Brass or Electro-galv. finish 12" on center (typical both sides) —Angle iron to be drilled and threaded to receive screw. —Concrete to be dri�led to allow screw to extend into the concrete (rypical both sides). 3" #4 Bar Welded at 12" on � S ECTI O N GC center, Nelson Standard Anchor or equivalent. (rypical both sides) COMBINATION CURB, GUTTER, AND SIDEWALK 6" VERTICAL CURB, GUTTER, AND SIDEWALK SECTION A-A (2 VIEWS) STANDARD DETAILS FOR DRAINAGE UNDER SIDEWALK LARIMER COUNTY CONSTRUCTION REVISION N0: 1 DRAWING URBAN AREA DRAWINGS STREET STANDARDS DATE: 04/O1/07 '709