Loading...
HomeMy WebLinkAbout03207 - Technical Information Report - Drainage • r � � Good Homes Short Plat (Gough Development) Drainage Report Prpared by: James E Haynes PE 1822 109�' Ave Ct E Edgewood, WA 98372 (206) 715-5159 ; � 5 E' H14 �'' ��i��F WAS/y���,� ti .. ' r m � . �/�' ��- oes4t��, ;� �F-� ��;,.. �-:� �,c.l ` '��f , `" `S='2:��t�:LF:�., `�;� . �`'��.�_..:'1.:._., C �_..� , � "C �- �� i Prepared by: J. Haynes Good Homes Short Plat � v �} a �—�J -�� Date: 4/15/2004 (Gough Development) Drainage Report �" Pa e � 3207 - � TABLE OF CONTENTS Paqe TECHNICAL INFORMATION REPORT WORKSHEET 7- � Existing and proposed features Core and Special Requirements Discussion Level 1 offsite analysis summary , Prepazed by: J. Haynes Good Homes Short Plat Date: 4/15/2004 (Gough Development) Drainage Report n , TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND Part 2 PROJECT LOCATl�N ANG� PROJECT ENGINEER DESCRIPTION Project Owner Project Name �D�v�s 2�� �sr,aT� Gn.P- Go�o� l-�oM�s S'1� Address Location Township �-3 N Phone �-� Range Project Engineer •••••••••••••Section �- �Rh��S NAYN�"S � Company �p,zZ io9TH Nv GT � ' Address/Pho e��U� 9�7y Part 3 TYPE OF PERMIT ,Part 4 OTHER REVIEV'JS AND PERMITS APPLICATION Subdivison DFW HPA Shoreline Managemer;t Short Subdivision COE 404 Rockery , Grading DOE Dam Safety Structural Va!�Its Commercial FEMA Floodplain O�her Other COE Wetlands Part 5 SITE COMMUNITY'AND`DRAINAGE`BASIN Community c,?� �� �2�-,�-�,� Drainage Basin f�D�v�`� G��� Part 6 SiTE CHARACTERISTICS ' � � River Floodplain � Wetlands ; Stream f�dN6 Y GlLd�K ' Seeps/Springs � Critical Stream Reach ' High Groundwater Tab:e , I Depressions/Swales Groundwater Recharge I ( Lake ' � Other � I Steep Slopes .�S�o 5.� Cu��� � � Prepared by: J. Haynes Good Homes Short Plat Date: 4/15/2004 (Gough Development) TECHNICAL INFORMATION REPORT WORKSHEET , Pa =e ' , Part 7 SOILS � a Soil Type Slopes Erosion Potentiai �rosive Velcoties Additional Sheets Attached I Part 8 DEVELOPMENT LIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT I Ch. 4— Downstream Analvsis � Additional Sheets Attached Part 9 ESC REQUIREMENTS `� + I MINIMUM ESC REQUIREMENTS MINIMUM E9� REQU:REh^ENTS DURING CONSTRUCTION AFTER CONSTRUCTION Sedimentation Facilities Stabilize Exposed Surface � Stabilized Construction Entrance Remove and Restore Temporary ESC Faci!ities ' Perimeter Runoff Control Clean and Remove All Silt and'Deb�is Clearing and Graing Restrictions Ensure Operation of Permanent Facilities over Practices Flag Limits of SAO and open space onstruction Sequence preservation areas � Other Other Prepared by: J. Haynes Good Homes Short Plat Date: 4/15/2004 (Gough Development) TECHNICAL INFORMATION REPORT WORKSHEET �� � s.� � � Part '10 SURFACE'WATERSYSTEM.� � ��✓lethod of An�lvsis I Grass Lined Tank Infiltration 1 TiDs-�9L�� 1 Channel Vault Depression Pipe S stem Compensation!h-litiga:i Energy Dissapator Flow Dispersal on of Elimina;ed Site Qpen Channel Wetland Waiver Storage Dry Pond N�A Stream Regional Wet Pond Detention Brief Description of System Operation SN�rr�'T Fls.�.c� ��crc3t� c��cATcN 73AS>�S - «�vv��H.� Tr) 4'XtST ��Gr 1,ITi�S Facility Related Site Limitations ' Reference Facility Limitation ��k'.�I�L's , I . � Part 11 STRUCTURALANAtYS1S Part 12 FASEh9ENTSrfRACTS ' Cast in Place Vautt Drainage Eesement ! Retaining Wall Access Easement Rockery > 4' High Native Growth Protection Easement Structural on Steep Slope Tract I Other Other ; � Part 13 .SIGNATURE OF:PROFESSIONAL'ENGINEER . � I or a civil engineer under my supervision my supervision have visited tne s�te. Act�ai site conditions as observed were incorporated into this worksheet and the attachments. To the best of my knowledge the information provided here is accurate. Si ned/Date Prepared by: J. Haynes Good Homes Short Plat Date: 4/15/2004 (Gough Development) TECHNICAL INFORMATION REPORT WORKSHEET Pa<�e o � ' ExistinQ and Proposed Facilities Existing Facilities The site is currently a single family lot. It is approximately 0.73 acres in size. There exists 3 I separate structures, or portions of structures on site: one vacant house, one garage pad/ foundation, and one dilapidated shed. There is also a gravel driveway along the northern property line. The driveway is about 150 ft long. The Honey creek stream flows adjacent to the southern property line. Drainage form the site is by infiltration, sheet flow into honey creek stream basin. The house roof downspouts currently use splash blocks dispersion methods for runoff. There exists a 24" public drainage system along Union Avenue. An existing type II catchbasin exists near the property, collecting runoff from Union Avenue. Proposed Facilities This project proposes construction of 6 new single family residences. Existing structures will all be removed. A new paved access easement (163' long) will be provided also. Driveway catch basins, Type I and type II catch basin with pipe conveyance sytemes will be used to collect runoff form lots 1 through 5. Runoff will then be conveyed to the existing drainage facility on Union Avenue. Lot 6 runoff will dispersed through on-site dispersion trenches, then allowed to drain into Honey creek. Sketches The attached sketch show a plan view of the proposed drainage system. Prepared by: J. Haynes Good Homes Short Plat Date: 4/15/2004 (Gough Development) Drainage Report .-, P e _`� . . i 40' 20'-10'-0' 40' NEW 8"SS MAIN CB-1 TYPE 1 .� NEW CATCH BASIN 26'ACCESS SEE SS PLAN) IE=384.2(V1� RIVEWAY INIET CB-3 TYPE 1 EASEMENT IE=384.1 (S) (TYP)DETAIL SD-1 IE�384.5(W) (20'PAVED) NEW CATCH BASIN RIM=389.5 _ RIM=391.3 CB-2 TYPE 1 SEE DETAIL SD-2 IE=384.8(W) WM WM ; IE=384.8(3) 12" , IE=384.7(E) 36" RIM=390.5 � i ; `�� '` SEE DETAIL SD-1 � i '' ' UNOFF FLOW DIR. PAVEMENT I • ,' � EDGE —NEW WTR MAIN ' li , y ,, . . � , — • — . . . i �. '� ,',. _ . . . . (SEE PLAN) . , , . . . _ . . . � . . � . � . � „ � � , � , , � , , ' ' � � ' ' ' — ' — ' NEW SS MH , , , , � ; `. ' ,', �( ---- E P N _ ' � ,. � � ; ' ' �. � " '�' ——— ��h �,�. , � S�'C �i , , .. 1 ______ _ _ � � �� � � , � ___ _ _______ .�,. ; � ��,',LOT 6(MIN � •. ; BAS 'fY�E°�` , • � -- IE-3 6� � ---- ---- � - 28'N � �� ,,� �,`FF=388.5) �► ---------o . ( ) �! � IE=3 3;78;(S) i Z � LOT 1 I TIE IN NEWV SD i �'� � (MIN FF=387.7) IE�3$3;9(W) i � ` LOT 5(MIN LOT 4(MIN . � �EXST � ' ' � '� FF=388.5) LOT 3(MIN ��;8"SS EXST SS p�'. `. : 385' FF=388.0) � � �' DISPERSION FF=388.0) ~'� � ' � IME--3 5 68(N) ` TRENCH , 8� ,, lo: ; ' _ DETAIL SD-4 ' � � � IE-385.57(E) PROJECT 383' �� LOT 2 �;-.�--;---•-- - _l., , � 1 " (MIN FF=387.5) • I � BOUNDARY 1 I � i • '-- - - ' ' � - - - ' ---- ' f -� --. ---- - :, _,.` - -- -� • • _ . . — � : — . . _ . . _ . _ E+N CA�'CH BA$i � `'' , . . ....................... ' ,�N , I ...... , I ' I _,_ ' : 381' ,. �.,_ ,.. . ; , � , , CB-4 t1fpE _._._ _ . ' � IE�383 2 N � � IEd383.12(S) ! �I � � IEq38�i.35(VU) � � � , NEW CATCH BASIN i � 50'SENSITIVE , CB-4 TYPE 1 R�I�A=389:9 ' ���` AREA BUFFER IE=385.0(N) � 3E�DE�AIL SD-Q �� I RIM=388.0 i W' , � . SEE DETAIL SD-1 � � z� � � • ' ���� i - i � ,,. w I � • - ; � .......` .��`� I � ' Q � I • . . (1►� � � � � ; . , � � , zi EXST 12"SS� ,:�� • � Z� � �� � �• i ��� � � I � i ', �� � I ' i EXST 12"SS �� i � � � � i j � � � I � I � Prepared by: J. Haynes Good Homes Short Plat Date: 4/15/2004 (Gough Development) � Drainage Report Page � ' � . � " Core Requirements Review 1. Discharge at the natural location —The existing site drains to the south and into Honey Creek. The developed site will have lots 5 and 6 drain to Honey Creek. Remaining drainage is still to the south. Runoff is then collected and conveyed to the existing facilities along Union Avenue. The direction of runoff is maintained. 2. Off site analysis —A level 1 analysis was performed (see page ). No runoff flows onto this property from other areas (except from stream flow from honey creek). No current problems were observed during field inspections. 3. Flow control — a preliminary runoff calculation was performed. Net increase in total peak runoff due to a 100 yr design storm was less than 0.4 cfs. This was a conservative analysis, assuming all runoff is collected and conveyed to single point of outflow. Since lot 5 and 6 runoff wilf be dispersed separately from the other lots and easements, the actual concentrated flow will be even less than calculated 4. Conveyance system —systems were designed to ensure that 25 year peak flow rate capability is achieved. Since the peak flow rate for the entire project (0.98 cfs) is so small, minimum 4" dia pipe systems at 0.5% slope are more than adequate to handle all runoff. 5. Erosion and sediment control —There exists some steep slopes along the southwest portion of the site. A minimum set back of 50' has been maintained for all above ground structures to ensure no increased hazards are created. For lot 6 structure, this buffer has been altered slightly to range from 40 ft to 60 ft. This variation maintains and acceptable average buffier of 50 ft. Additionally, all exposed areas willl be landscaped or otherwise stabilized. Filter fencing, mulching, stabilization, construction entrance control and other BMP's will be employed during construction to minimize erosion and sediment runoff from the site. Special Requirements: 1. Sensitive Areas— Honey Creek requires a sensitive area buffer to protect the water quality and steep slopes. This buffer has been accounted for in the short plat. Prepared by: J. Haynes Good Homes Short Plat Date: 4/15/2004 (Gough Development) Drainage Report Page � -� . _ , , I � ' Level 1 off site analysis The site was inspected in December and February of 2004. The site topography is uneven. The , highest point is about 394 ft. the lowest point, near honey creek is about 373 ft. There are steep , slopes at the edge of the site. No construction will occur within 50 ft of these slopes. No runoff was observed to flow from off site to this property. Honey creek flows onto then off of the site. The site drains mainly to honey creek via sheet flow and .or infiltration and sub surface flow. Calculations of pre and post developed runoff from the site were performed. See attached sheets for calculations. There was no evidence of runoff or erosion problems on the site. Soils encountered were mainly topsoil mulch to a depth of 6" - 18". Clay, silt and sandy gravel were all encountered below this location. Since the site will not be used for infiltration, no further soil analysis was performed. Prepared by: J. Haynes Good Homes Short Plat Date: 4/15/2004 (Gough Development) Drainage Report Page �U � �. Good Homes Short Plat • ' 1425 Union Ave NE Renton, WA 98055 Calculation of pre and post development storm water runoff peak flows. Sub basin description: 95'X 260' lot located west of Union Avenue and 1/2 block north of Sunset Blvd in Renton, WA. The site has uneven topography, with the total eleveation difference of about 6 ft. There are no steep slopes located on the lot. The lot vegetation and ground cover is mostly overgrown grass and shrubs. Two large evergreen trees are located approximately 100'west Union Ave and 20'south of the property line. The natural, existing runoff path is generally to the south into the Honey creek basin. Maximum pre-developed overland runoff flow distance is 95' (width of lot). Runoff calculation method-Rational method Time of concentration (Tc): Existing Impervious Are: Exst House: 826 ft Exst Shed: 537 ft�QU� h'"� °L1 TOTAL: 1363 ft2 C�„�y��� Due to the short travel distance, assume Total travel tim =6.3 minutes (�,� Tc= 6.3 min. Runoff Coe�cient(Cc): �';'''�,' �' ;�� ;' Impervious area (A1): Driveway(gravel) (2): Lawn/orchard (A3): A 1 = 1363 ft2 A 2= 1200 ft2 A 3 = 22061 ft� C1 = 0.9� C2 = 0.85 C3= � - �'' Cc= 0.313 • �; �.c',; +- � - _ . , � � '� .��'�� a r,�� =� _-- -�,-- - - i 100 = 0.819 '� P 100= 3.9 in. I 100= 3.19 Q100 = �cu. Ft/sec (Peak runoff flow for undeveloped site} , �� i�� For post developed site: New impervio e�? , . A 1 = .255 acr , ��-✓�' A 2= �9�acre C1 = 0.9 C2 = 0.25 Cc 0.5434 All other values a�same as pre-devloped _, . ,� Q_100= �1 cu ft/sec Change in run off if less than 0.5 cu ft/sec OK! Prepared by: James Haynes PE Good Homes Short Plat Date: 8/23/04 (Gough Development) Drainage Report Page 6 o f