Laserfiche WebLink
Guptil Site,04-RS-00] <br />Apri128,2004 <br />Page 4 <br />APPENDIX D <br />wetland; however, this will ha�e to be verified with a wetland delineation. If a storm sewer is <br />not allowed as a wetIandlwetland buffer impact, stormwatermanagement for the site will need to <br />be reevaluated. <br />The stage storage data for the proposed detention basin to be located on the Armory site is <br />provided in Table 2: <br />Tt�l� �,. r Dils far R Fomd <br />E���di� �� Ar�s <br />�lora� -f <br />� S�oea�c <br />Live Storage <br />�8� <br />��F <br />�88 <br />6�� <br />��I <br />892 <br />893 <br />894 <br />�� <br />73 � <br />j� <br />�.��� <br />5,�6� <br />�,$�� <br />11,582 <br />14,802 <br />17_550 <br />V�1wae Tatal <br />vu, ft, <br />� <br />�$$ <br />� ��4 �e�d �tor�� <br />� 9�� I �,1�1 �q, �_ � <br />� S l � �.��� a�-� <br />� ��� <br />9 629 Live Storage <br />13194 45,528 sq. ft. _ <br />16.176 1.05 ac-ft <br />I-iydroCAD, a computed aided surface-watermodeling tool was used to simulatethe flow rates <br />for the existing and proposed conditions, based on the total developable area. The proposed <br />conditions model incorporatesthe Live Storage portion of the proposed pond data in Table 2. <br />The following parameters and assumptions were used in the HydroCAD models: <br />+ The SCS TR-20 hydrograph method was chosen. <br />* The curve number (CI� values used in the HydroCAD models wa� 98 and 68 for <br />impervious and perviaus areas, respectively. The existing conditions model included the <br />house, garage, and driveway for a total impervious� of 4,727 sq. A. The proposed <br />conditions model included the 11,000 sq. ft. and 25,000 sq. A. impervious areas <br />calculated for the Elmer Street Parcels and Guptil Parcel, respectively. <br />* Rainfalls assumed were 2.8 inches, 3.6 inches, 4.2 inches, and 5.9 inches for the 2-, 5-, <br />10-, and 100-yr, 24hr storm events, respectively. <br />+ The time of concentration (TC) used were 12 minutes for the e�sting conditions and 10 <br />minutes for proposed conditions <br />■ A pond outletwas modeled to produce a discharge of approximately 2 cfs, as was found <br />in the City of Roseville's Surface Water Management Plan for the existing pond. An <br />outlet elevation of 888 feetwas assumed. <br />� No infiltration is included in the modeling <br />