<br />Reach No. 3 (Plate 7)
<br />
<br />The New Mercer Canal carries the runoff from the upper portions of McClel-
<br />lands Basin to Mail Creek. During periods of high rUllOff, the depth of f10w in the
<br />canal becomes greater than orjginally designed for. This results in the inundation
<br />of the ditch service road on the east and some associated erosion damage. At the
<br />confluence with Mail Creek, excessive discharge velocities could cause some additional
<br />erosionand/ordepositionofsiJt. Fina1Jy,overtoppingofthelarkboroughSubdi_
<br />vision detention pond along its east bank will also contribute to the flooding and
<br />erosion problem in this reach.
<br />ReaCh NO.4 (Plates 8 and g)
<br />
<br />There is a substantial amount of overland flow through the streets and yards
<br />in larkborough Subdivision during the lDO-year storm. Although the flows are not
<br />above the first floor elevation for any of these units, there is the potential to
<br />have structure and content damage to seventeen (17) homes. Between larkborough and
<br />Shields Street, the floodplain consumes a considerable amount of ground whiCh is
<br />presently in agricultural use. During floods here. there exists the pot€ntial for
<br />crop and/or flood damage.
<br />
<br />Reach No. 5 (Plate 9)
<br />
<br />The Shi€lds Street crossing consists of one 15-inch corrugated metal pipe.
<br />As a result, Shields Street is overtopped during euen minor storm events causing
<br />traffic interruption and some erosion problems. Upstream of Shields Street, con.
<br />siderableagricuJturalgroundisconsumedbyfloodplain. Finally,duringflooding,
<br />the Pleasant Valley and Lake Canal would probably breach and thus require repairing
<br />and probable removal of some silt deposits.
<br />
<br />ReaCh No. 6 (Plates 10 through 13)
<br />
<br />The lower portions of the McClellands drainageway have extremely wide flood.
<br />plains as a result of backwater behind culverts at both Timberline Road and the Union
<br />Pacific Railroad. Both of these crossings would be overtopped by 1O.year storms or
<br />greater, and would be in danger of washing out. Because of the tall and steep em-
<br />bankment of the railroad, extensive damage to the railroad as well as adjacent pro-
<br />perty could result during a storm of 2s.year frequency or greater.
<br />Upstream from Harmony Road, the McClellands drainageway has been improved as
<br />part of the residential development which has taken place. and all improv€ll1€nts are
<br />adequate for the IOD-year' design flows. No flOOd hazards are apparent in either of
<br />these reaches.
<br />
<br />lV.3
<br />
<br />-
<br />.
<br />>
<br />-
<br />
<br />"
<br />~
<br />"
<br />~
<br />
<br />-
<br />.
<br />o
<br />
<br />-
<br />
<br />"
<br />.
<br />.
<br /><
<br />~
<br />
<br />:J
<br />o~,
<br />l-O:EL
<br />"'- ....,... "" "" ..,. ..,. N ..,. 0 ,... "" '" 0 N '" "" "" "" '" .... .... 0 ... ...
<br />." .
<br />>-"',..,... oo~ 00,... '" "" '" 00,.,,.,..,. 0,...,......,.,,..,... N", '" "" '" ""
<br />, ,..0 0 0,...,... ~ ,... ~ N N N ... ... ... ... ... ... ... '" '" 00 00 00 00
<br />o OI-D "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" ""
<br />0_ "'. ..... . . .
<br />_w ............................,....................................,.....................
<br />"
<br />.
<br />
<br />~
<br />O~
<br />" o.
<br />"'- .... _ ..... _ '" "" '" _ '" "" '" .... N '" 00 00 00 ,.., 0 '" "" m ,., ...
<br />.".
<br />>-",,.. 0 ""....,... '" ~ "'..... "" ""..,. "" 0 0 ~ ~ _... N'" N'" '" '"
<br />''''000 0 ~ _ '" _ ~ _,... N N..,...,..........,.... '" '" 00"' 00"'
<br />OOl-D "" "" "" "" "" "" "" "" "" "" "" '" "" "" "" '" "" "" "" "" "" '" "" '"
<br />"'~'" . .. . . . .. . .
<br />w ...........,...,...,.......,..........,.....................,.........,...........,....
<br />"
<br />.
<br />
<br />~
<br />O~
<br />l-O::E: 0 '" ~ .... ... "" _ .... '" ... ..... N N ..... ... 0 '" '" .... 0 '" .... N N
<br />"'.~ N ~ ~ _ "" ... '" "" ..,. ..... N '" '" N N _ 00 '" N ... '" '" "" '"
<br />." .
<br />Vl >-..,.. ""....... 0 N.......... ""....... 00 00 "" _ N "" NON.............
<br />Z I,..O"'OO____~~~NNNN............."''''OO<OOOOO
<br />o '" 0>.0 00 "" '" '" '" '" m "" '" "" "" '" '" '" '" '" m m '" m "" "" "" '"
<br />_ N_" . . . . . . . . ."
<br />w ........ or ..,. ... ... .... ... ... .... or or .... .... .... .... .... .... .,. ... ... ...
<br />"
<br />.
<br />
<br />"
<br />-
<br />o
<br />z
<br />a
<br />u,
<br />"'
<br />"
<br />a
<br />"
<br />a
<br />"
<br />"
<br />o
<br />:1
<br />~
<br />"
<br />"
<br />"
<br />"
<br />"
<br />g
<br />
<br />" "
<br />
<br />-
<br />~
<br />O~
<br />uo.
<br />"'~ ......... '" - '" '" ... ,...
<br />." .
<br />>"',.. '" N '" m N.... or.... "'............. 00 00 0 _ "'.... "',... _ M or..,.
<br />''''0''' 0 0 0 ~ _ _ ~ _ _ N N N N ... ... ... N .... '" "'0 ~ 00 00
<br />00>..0 00 '" "" "" "" "" "" "" '" '" '" '" '" '" '" '" '" '" '" '" ~,'" '"
<br />~-'" . . . . . . . . . . .. . . .
<br />w ..,...............,.........................,........... or or ... ... .... .... ... ....
<br />"
<br />.
<br />
<br />00
<br />
<br />" 0 0
<br />
<br />..,. '" '" 00 '" ~ _ ~
<br />
<br />00
<br />
<br />~
<br />=""1", "" 0..... 0 '" "'... '" N NO", 8 "'..... N _.............. "'...
<br />~~~~ .... '" .... 00 00 0 _ ... '" '" '" 00 ~ .... _ "" _ '" '" N .... 00 00
<br />>-"',.."'O.........ONNN'" 0"'''''........'''''' ...."'0_
<br />',..0 '" 0 0 0 _ _ _ ~ _ N N N N N '" ... '" .... .... 00 00 00 00
<br />N 01...0 "', "" "" "" "" '" '" '" "" "" "" "" "" "" '" "" .... "" "" '" "" '" '"
<br />~'" .. ... .. . . . . . .
<br />w ................,. .,......... ... .... .... ........ .... .... ... .... .... ....
<br />. "
<br />- .
<br />"
<br />c: ::;-:
<br />c =""1
<br />g g'.~::E: ... "" ... .... ... 0 N .... 00 <D M .... 00 .... .... ... '" N ... .,. ... ,., '" '"
<br />..J 3......'"
<br />..... _"',.. '" 00.... "'.... 0 0 CON 00.,.... '" '" '" _ "" "'..... "" 0 "" ""
<br />.2 [j,g ~ g;: ~ ~ ~ ;; :;; ;; ;; ;; ;; g; &: g; 8:: s: ~ g ;g; 'g, :;:; :iR g; g(
<br />..........., . .. '" . ... ..
<br />w... .... .... .... .... ... ... ... .... or .... ... .... ... ... .... .... .... ... .... .... ....
<br />
<br />o
<br />-
<br />.
<br />"
<br />
<br />" "
<br />
<br />" "
<br />
<br />~
<br />~
<br />~
<br />".
<br />U
<br />
<br />" "
<br />
<br />"
<br />.
<br />-
<br />
<br />~
<br />-
<br />
<br />. .
<br />00
<br />. .
<br />~ ~
<br />
<br />. .
<br />> >
<br />1':: 1:
<br />00 0
<br />U
<br />>
<br />E
<br />
<br />~
<br />
<br />o
<br />E
<br />-
<br />>
<br />
<br />. .
<br />> .
<br />. .
<br />" "
<br />U U
<br />
<br />c
<br />~
<br />
<br />-
<br />"
<br />o
<br />~I ~ =;
<br />
<br />~ ",210 0 8 '" 0 0 '" ::0:
<br />o,..B 0 0 0 "" '" ....
<br />::: ..8 '5 ~... ...
<br />","", ~I
<br />t: ~,= N '" _ ~
<br />
<br />- -
<br />. .
<br />" "
<br />
<br />00
<br />N .
<br />
<br />8 8
<br />
<br />o '" '" 0 "" 0
<br />'" ~ '" "" 0 ""
<br />>
<br />
<br />~ "
<br />M M
<br />
<br />N N '" '"
<br />00 ... '" ....
<br />............... ...
<br />N 00 M .... ... '" '" a..
<br />... .,. "" '" '" '" '" '"
<br />
<br />8 8 8
<br />
<br />>
<br />
<br />>
<br />
<br />>
<br />
<br />>
<br />
<br />>
<br />
<br />> >
<br />" .
<br />N N
<br />
<br />>
<br />
<br />.
<br />
<br />>
<br />
<br />>
<br />
<br />>
<br />
<br />.
<br />
<br />.
<br />
<br />>
<br />
<br />'" "" 0 0
<br />~ ...... N N
<br />
<br />N M M
<br />M M ~
<br />
<br />'0
<br />~o 0 ~ N M ... '" "" .... 00 '" 0 ~ N ... .... '" '" .... 00 "" 0 _ N M
<br />~- 0 0 0 0 0 0 '" '" 0 0 _ _ ~ _ _ ~ N N N N
<br />o~ ... _ _ ~ _ _ _ _ _ _ _ ... _ _ ,... _ _ ~ _ _
<br />l- U , , , , , , , , , , , , , , , , , , , , , , , ,
<br />wO> x x x x x x x x x x x x x x x >< x >< >< >< x x x x
<br />~
<br />
<br />IV-4
<br />
|