HomeMy WebLinkAbout19600 63rd Ave NE_PWD1146_2026
Snohomish County
Public Works
M E M O R A N D U M
Date: October 24, 2017
To: City of Arlington
From: Scott Davison
Subject: North County Recycling and Transfer Station (NCRTS) Lane Widening - Drainage summary
Project: NCRTS Lane Widening: RR8551 UPI 06-0035
Owner: Snohomish County Department of Solid Waste
Project Description:
The proposed project will widen the existing pavement and re-stripe the pavement to allow an additional outbound lane
from the unloading zone to the existing scale. The length of the new lane will be approximately 400 ft and the width will
be 12 ft. The current configuration has two 12 ft inbound lanes and one 12 ft outbound lane. Most of the pavement
required for the new lane is existing and can be utilized by changing the geometry of the pavement striping. The total
area of the new pavement required is approximately 1,200 sf. This project is not part of or connected to a “Common
Plan of Development†as described in the 2014 SWMMWW.
Drainage quantities:
Total site area SF 387,800
Existing impervious SF 166,100
New impervious SF 1,200
Replaced impervious SF 180
New plus replaced SF 1,400
Existing and proposed drainage:
Roadway runoff from the existing pavement sheet flows generally to the east and enters one of two depressed grass
areas. Some of the water from the northeast most area sheet flows to the east and enters a type I catch basin (CB#1).
Water flows from CB#1 to CB#2 in an underground 6†pipe. The rest of the water in the northern area sheet flows off
the pavement in a southeast direction then flows across a grass area for approximately 30 ft where some of the water
infiltrates and the remainder enters a 6†vertical pipe that has a grate. The water then flows through this pipe to the
southwest where it connects to a type I catch basin (CB #2). Runoff from the southern area of pavement sheet flows off
the pavement in a northeast direction into a grassy depressed area. Some of the water infiltrates before entering CB#2.
Water leaves CB#2 through a 6†pipe that flows to the east for approximately 100 ft where it enters a water oil
separator. Water leaves the separator to the east through a 6†pipe and flows for approximately 15 ft where it enters a
type I catch basin (CB # 3). The water leaves CB#3 to the north and south through 6†perforated pipes which disperses
the water into the ground through an infiltration trench. The existing drainage facilities were installed as part of the
original waste facility construction.
The existing drainage patterns will be maintained with no proposed changes to them. Flow charts from the City of
Arlington website were used to determine the minimum requirements for this project. The only applicable minimum
requirement for this project is minimum requirement #2 Construction Stormwater Pollution Prevention. See attached
site plan, photos, flow charts and SWPPP.
www.snoco.org
!"#$%&'()*+,&(&%-
./ 0 %+1+(231"+4%-56*+)&*-57(-
./ 0.8899 :+;<&=&>>&*,&%4&
./ 0?@?A?B ,&*&--CDEF
@ 0 9 0 2;1$&>(2-1
G 0 FHI:EEIH D
J/ (2;1$&>K3(2-1L3%+;+K+*7
A MN O PP$PP2-2+%$>>$%&
Q/R 0 K
D :*P,&%4&!
S @ 8 " T
S99R8 F
JU9
AR9 "6#
.99V08 #$4%$W>$;<
6$*;&>X PP*&33#&7$>T&3;*2)-2+%Y%&*!$(& Y%&*61+%& Z+%2%7
: H
D :T[ ! !\'\" EH+>2P$3-&
66] T23)+3$>
F
/0^_`9
T$-& &,2&Y5)&T&3;*2)-2+%3327%&P+$*7&-T$-&
F ]T'!]!+,$\&$-+% F
a9
b&&T&3;*2)-2+%!+-&3(+4%-
6*+;&332%7&;1%+>+75 cFHK
"2,2>6&*(2- c C K
/ de?fghijj
09
T$-&6$2PW5T&3;*2)-2+%6$5(&%-5)&;;&)-&PW5(+4%-
DF '"\ #'\
!"#$"#! % &'() *''+, -(*.) /'(. ;8+ )*?
-0 /'(.1
2. ( 3 4)(+5+ ., 6(7 . ,89'() 3 . :2/ ;+ <'=6'+, + .
*''+, , 3))7,
>), +,8 .(, 7? , @''+ >)+ 3 6)='+@ 7(. =6(8, ('=6'+,
. ,( ,()) ', +) A8('+ B#0 :3 /C--CC
D) 0 4==+ (E F1 3 3(+((+
3 ''+ >)+ 3 6)='+0
2. ( 3 4)(+5+ 8,, . /C--CC
*8+ ((+0 >), 8= 3)7*., 38+
3'
. G9 #!!H '+8)0 I2.+? 8 3 '?(+5 8, 7 ., 8 *., ,()) +
8 79,(1 7 7()) '6 .'J
<3 8 .6 + A8,(+, *+*+, 5 (+5 . 96 *''+,1 =), *+* 6
K+1 LM!N$!LNL$L% +.+O)(+5+70560
P8 ' ,89'( )*+(*)) * O)(+5+70560
2.+? 81
;8+ >,+1 >2
QR S
G() '
"!M"#! % TUVUTWWXWWYZ[\]]^_` a_bcdefg`h
"!M"#! % TUVZijUXWWYZ[kggblm_` anop]fg`h
!"L!"#! % TUYqVqZXWqXjqXWU rbodpos_ c_clfg`h
!"L!"#! % TUYqVqVXWqXjqXWU tnlu vwobe]fg`h
!"!x"#! % TZiTUyTXqZXqqjV zde_ anopfg`h
!"!x"#! % TZiTUiZXqZXqqjVX{v|}z Zqfg`h
!"!M"#! % TZiWVqyXWWYZ[~~vvfg`h
!"!M"#! % TZiWVqiXWWYZ[rbodpos_ z^ccobfg`h
!"!M"#! % TZiWVqUXWWYZ[kggnd€oedlpfg`h
!"!M"#! % TZiWVqZXWWYZ[anop]fg`h