The URL can be used to link to this page

Home My WebLink About03217 - Technical Information Report - Drainage TABLE OF CONTENTS Section 1 Existing Site Conditions....................................................................2 Section 2 Proposed Development......................................................................4 Section 3 Downstream Analysis........................................................................6 AppendixA ...........................................................................................................8 Technical Information Report Worksheet Vicinity Map CG Engineering—Project#04113.20 -- Level 1 Drainage Report for Eastway Center Addition Page 1 . � ' EXIS'TING SITE CONDITIONS � � � � � � CG Engineering—Project#04113.20 -- Level 1 Drainage Report for Eastway Center Addition Page 2 EXISTING SITE CONDITIONS The proposed project site is located in the City of Renton, Washington, Township 23 North, Section 16, Range 5 East,more specifically near the S.W. corner of Union Avenue N.E. and N.E. 4th Street. The main access is off N.E. 4`�' Street along its northern boundary. A vicinity map is included in Appendix A. The project site is located within a rectangular shaped parcel with a total area of approximately 1.7 acres. The existing project site is presently developed with a 26,208 square foot building, � currently utilized as various retail stores with associated parking and landscaping. The building was constructed approximately in the late `80's. The proposal is to construct a new 3,024 square foot building located at the southeast corner of the project site and relocate an existing catch basin with associated asphalt paving in the parking lot as needed. There is an existing trash enclosure that will need to be relocated along the western boundary of the project site. There is no upstream tributary drainage identified to be entering the project site. There are several catch basins scattered throughout the parking lot. Before stormwater exits the site it enters a 48" CMP detention pipe. Stormwater then exits the site and travels in the storm drainage system in N.E. 4`h Street, where it follows its natural drainage path to the west. On-site, there is an existing six inch sewer line that runs west along the northern boundary of the property line where it then connects to the existing sanitary sewer in N.E. ' 4th Street. There is an existing sanitary sewer manhole located near the northeast entrance of the project site which discharges into the existing sanitary sewer and flows to the west along N.E. 4`h Street. '� CG Engineering—Project#04113.20 -- Level 1 Drainage Report for Eash��ay Center Addition Page 3 I PR OPOSED DE VEL OPMENT & DETENTION ANAL YSIS CG Engineering—Project#0411320 -- Level 1 Drainage Report for Eastway Center Addition Page 4 PROPOSED DEVELOPMENT &DETENTION ANALYSIS King County's "Surface Water Design Manual" 1990 was the reference used for this design. The existing project site, 1.7 acres, is presently developed with an 26,208 square foot, currently utilized as retail stores with associated parking and landscaping. The proposal is to construct a new 3,024 square foot building located at the southeast corner of the ' project site and relocate an existing catch basin with associated asphalt paving in the parking lot as needed. There is an existing trash enclosure that will need to be relocated along the western boundary of the project site. Major paving is not anticipated. No new impervious surfacing will be added to the site. Existing drainage patterns will remain the same, and no new stormwater flow is anticipated. All existing catch basins will be utilized and stormwater will flow along its natural drainage course. A six inch sanitary line will connect to the existing sanitary sewer with a cleanout, exit the site to the north and flow into the existing sanitary sewer running along N.E.4�Street. There is an existing 12"water main in N.E.4`�Street. There is currently a 10" loop located in the parking lot that connects to the water main in N.E 4`h Street that serves the existing retail stores. The existing ten inch domestic line is to remain in place. There are currently four fire hydrants on the project site. ; CG Engineering—Project#04113.20 — Level 1 Drainage Report for Eastway Center Addition Page 5 DO WNSTREAM ANAL YSIS CG Engineering—Project#04113.20 -- Level 1 Drainage Report for Eastway Center Addition Page 6 DOWNSTREAM ANALYSIS The downstream analysis system for the subject site was investigated for approximately 1/4 mile in August 2004. Weather conditions for the weeks prior to the investigation consisted of moderate precipitation. On-site, surface stormwater sheet flows in a northerly direction across the site where it is collected by several catch basins located in various positions within the parking lot. Ultimately all stormwater is routed to the storm sewer system located in N.E. 4`� Street where it flows along its existing drainage course. Erosion is predicted to be minimal since all areas of the parking lot are paved with asphalt and is surrounded by a six inch concrete curb. Filter fabric covers will be placed per City of Renton's standards in all catch basins that will be subject to receiving pollutants such as oils, grease, and sedimentation during construction. The filter fabric cover will be checked daily during the wet season. It will be inspected during and after any heavy rainfall. Problems will be corrected prior to leaving the site. If construction vehicles transport soil and/or debris onto road surfaces, the roads shall be cleaned thoroughly at the end of the day. Sediment shall be removed by shoveling and sweeping and transported to a controlled sediment disposal area. Street washing shall be allowed only after sediment is removed in this manner. i � CG Engineering—Project#04113.20 -- Level 1 Drainage Report for Eastway Center Addition Page 7 il APPENDIX A � i i � � � � � � , � I CG Engineering—Project#04113.20 -- Level 1 Drainage Report for Eastway Center Addition Page 8 � ' ' Page 1 of 2 KEng County Butiding and Land Develvpment Divfslon TECHNlCAL INFORMATION REP�RT (TIR) WORKSHEET - . . . - . . . . � � . . � Eashva Ceater Eastway Center Building Addition � Project Owner y Project tVame � Address 3901 NE 4th Street Location Phone Township 23 Ross Jarvis R�� 5 East Project Engineer 16 CG Engineering Sectian _ Company Projeci Size 1.7 Acres AC Address Phone 425.778.8500 Upstream Drainage Basin Size N�A AC � , s • � � I j � Subdivision 0 DOF/G HPA 0 Shoreline Management i � Short Subdivision [� COE 444 O Rodcery � Grading � pOE Dam Sa1ety � Structural Vauits XQ Commercial � FEMA Floodplain 0 ��r � Other � COE Wetlands � HPA ♦ ► i � Community Renton-NE 4th Street i Drainage Basin E 7 -t •�- � River � Floodplain � Stream � Weilands � CriGca{Stream Reach [� Seeps/Springs � Depressions/Swales � High Groundwater Table Cl Lake __ 0 Groundwater Recharge � Steep Slopes �J Other Developed Business and Parking Lot I � Lakeside/Erosion Hazard . i Soil Type Slopes Erosion Poiential Erosive Velocities 1 -3% Slight � � �, Additional Sheets Attatched 1J90 � � Page 2 of 2 Ktng County BuIfdtng and Land Development Divlslon TECHNICAL {NFORMATION REPORT (TIR) WC)RKSHEET � . • . REFE RENCE LIMITATfOWSITE CONSTRAINT 0 Ch.4-Downstream Ana +I�sis � � O � � � I� ; [� Additional Sheets Attatched il � I� I MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS �I DURING CONSTRUCTION FOLLOWING CONSTRUCTION ! � Sedimentation Faalities � Stabifize Exposed Surface � � Stabilized Construction Entranca � Remove and Restore Temporary ESC Facilities y (� Perimeter Runoff ConVoi � Clean and Remove All Silt and Debris � Clearing and Grading Restrictions 0 Ensure Operation of Permanent Facilities [� Cover Practices 0 Flag limits of NGPES 0 Construction Sequence � Other I [� Other � ' � Grass Lined Channei t`� Tank � (nfiltration Method of Ana�ysis i � Pipe System � Vault � Depression { � Open Channel 0 Energy Dissapator � Flow Dispersal CompensatioNMitigation � Dry Pond � Wetland � Waiver of Eliminated Site Storage 0 Wet Pond � 5tream � Regional Detention Brief Descripfion of System Operation 1 Facility Related Site Limitations Q Additional Sheets Attatched Referencs Facility Lirr�tation None- Site is Developed . r. -•� i 0 Drainage Easement � Cast in Place Vault � Other � Access Easement i � Retaining Wall 0 Native Growth Protection Easement f � Rockery>4'High � Tract ; � Structura!on Sieep Slope C) Other . - . . � I or a civil engineer under my supervision have visited the siie. Actual 1 site conditions as observed were incorporated into this worksheet and the attatchments. To the besi of my kn�wledge the iniormation provided here is accuC2te. Sipn.dD�te I/9(} f,l Elm�� N� , � I � `�,��lt Awe N� � ��t i �1v� S� , �-��ti�� - � ��ell'ar��ve N,� � _- � � �� Bre��rtan"��P�ve Ne � _., �: �- ,; a� �,�i1�r y�a�� ...._.�,� _ T,� r` r..„�,� `i, c S`u ' '�'� �� '� If W�`N _ �� _~-�-' � � � �i �, r, .._�, �, , � ' �,L�i� �`it'�� , a � � � � ' � � � �� I --�`"f ^ �. _ — �_ � � � ;: Ut� �'�Tl,_��.'� �� ...._Z ---.� � _ _ �- c,� � � � � � Z�' � �;� r� �, ,_..._,—�.. �—� � ' �� #��fS � �� , f�F�ed rri�o r�d Ave N� �'i �'g�'d 4aaa�� _M<;__-ri:`< � 1 �.�� '�,�5 I �'��r1 �-f 1 � � � "C?lympia �,ve N��-°��. �'� �;! w k—� �c �a �- 1 �� -� � °� � �_.. �� — cC� cP , __.:�,, �;.:.._. a �. ! 6. �+ ,u d� �� RJlo�nroe Av'� �I� v____�:W_�______�-i i; � �7� �n� aaa�,o}� � a� � � y� ��Kirk�and A+�� 'Ne �. �, ci� �'-'_"5 .._�--�-I "5' � �'� ' ! ��, J�ffer�o n Av��h1� f �, .� ° �� — r--,.� � � ..�,4 �,, Ind�x pl t�1�e ��--� � Z . t � � r'__:_-_ . _ _ _ _ _ _ �