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HomeMy WebLinkAbout1993.06.04 - Howard Street Drainage Corridor AssessmentI, Lisa Palazzi,' Principai" 203 Fourth Ave. Fist j Olympia WA 95501 otig Milan on ort- :Townsend= ept.: of:.Public..Works 5214 Kuliri, Street Port-: Townsend, W_ _A 98368 ' 206)- 3857212 June_4, 1993 Report:;1`ile .Number: -P93- 0056.,--= Report ;Sitbject:. Howard Street.-Drainage Corridor assessment- - Location:`." -.Drainage. :e tending•-frosn, the southeast corner of the proposed C y' of Port _Townsend fi prat on site, .south to•Discovery Road, approx» 'following the Howard Street easement:. Inforssiation was collected aril 'the. edgg of the .diraitiage::corridor, vra. -flagg ed- on the: site on 'May _5--; -;' 1993 . by'Zisa Palazzi (soil sc%entise.,.: Pacifid Rim. Soil &.. Water) and Pesha Klein : (botanist,.. Sheldon':& Associates) : The fob louring report describes: out - ,tinning... briefly;-.:nd;. provides: cl•zrifi:catiori on some of the . flagging procedures: The wetlands:aetually within the boundaries of- the . pro.pbsed::filtratiori -site -_have =.been fully. delineated'. ~The: wetland edge _ix} tfioseA areAs.-has been- as precisely` located as possible since there are current ' ervelogment' glans for - the "'site The 'delineation far- -the - °rest. `of the . corridor" was.. precursory . to . a snorer precise., and documented de} neatlon:.' Tt e: purpose of this corridor evaluatidn -is more ` to a6t- ermine. generally :iirhexe :t'he primary :drainage. =path .lies rather .thari to:_ precisely...delineate any wetland -edges .` Because 'the..soils .are so . shallow-, : ri - some -areas, the jurisdictional wetland -edge may -be some.distance..inside' of the' flagged- boundary. =It- is - not expected that the edge of the jurisdictional.. wetland wxll. "be outside of the flagged boundary. Therefore., It is.generally tAfe to: Aaijiiae that ':thin fla nclvda:= the' major .wetlands: along 'the cor,440r:. . In ".the - text: bellow'; for _l c'c -'ct- .fetter fetus t6x flagged - a eas..ard called' tlaiids "': But` the for a..is in ende& "snore .to' desdribe regu] arty f obded areas a or g the• batto of :the.: "drainage . SITE.._GEOMORPHOLOGY . The Howard' Street drainage . corridor:, extends.from its headwater '.wetland. at the' -: southeast . - Co rner -af -.the. proposed City- filtration.site.in a south- southeasterly diirecti:on toward Discovery Road.: The upper = portions of-the corridor- are .- : re- atively. flat. with little -relief. Ele'Vation between the headwater area and Discovery Road only. drops 30 feet, or about -10 feet. peir -mile. The:.area south of' Discovery. _is quite flat'as` well ..making 'interpretation of basin .boundaries.. difficult'. = The .drainage corridor, is ,quite :..distinct ,in. most portions.: however -* it .-does y. r -un subsurface -iii _At."least two areas :'' As a re sultJ the 'corridor .is- actually .a series of :three .isolated wetlands :that .are not-.'connected-via surface :-•: hydrologic; features.. It.. can . be •assumed that they .'are connected .however. _ tlii ough subsurface, - hydrology : - _ The. .first wetland .extends-.south- southeast about 1_/2 of a mile. from'the corner of the proposed "filtration site.. "It is ,a :.Falustr he•.Emergent/ .Scrub- shrub% _ Forested- wetland dominated- by wild rose, .spirea;': "wes tern "redcedar, - hawthorne. and siough 'wedge. We: had `previously, _del iiieated the portion of the . wetland a:c.tually.'within the boundaries' "of the-,f3.1- t- i&tion- site:: The flags- 'for_"that. delineation are labeled in :numer cai.,order 1 through `32 in. a; counter- cl.ockwi.se direction.. The--rest..of the.fla . gs marking-the edge--of the'. off site portions o f the first wetland-ai:e labeled,. DCILA through vc;23A :_ih.a clockwise'. direction: Therefore, 'yhe'n.,assemblirig .this data for- survey,pIotting, the point at flag :l` should" be - connected' to. the point at slag' DCIA; :end :the .point _at fla-' 32.' .should be :connected to the pair t" at: flag DG23A - l rom: DC19A,.- there . is. a flagged lfie,, " south over the berm to:.the top o _ f. the second wetland: Those flags_ are labeled' starting:.at ;bG2/+A just. "for -the -sake = of,COntinuity.; - _Points" DC23A- and ;DC2/A.: should, not'be, connected .416ints,.DL' 4A anc DC25A simply mark`tlie berm crvssin _ r.: '.. Because `the berm was - deiisety vegetated; "i t was not : possible..to. -evaluate how: it" was .fornied:; But it is likely.o:be a ;-result. - -of old logging.act-- vities in the' area that inadvertently made 'a.•dam "across. "tthe .-sititle drainage. The..-secorkd- wetland is larger than 'the f first: and • extends for; more thari-• a` mile 'in a ' south - southeasterly direction..' Flag DC26A marks the "start of the second wetland,.. about 50 feet from the. southern end of the -first, -on the other side of the,.' ' . berm.. - The second wetland is. also "a Palustrine Emergent/ Scrub- shrub% Forested wetland dominated'by wild rose, "spirea red. alder, .willow •spp. , western..- redcedar ". hawthorne; . and: slough _sedge -. -. Flagging-- continues in numerical ..order'.- in a. :c1ackw "se direction to about 'DC84A. `Sorry; but my notes are.-not', clear:on the •exact.'numb_ear'.of t'he.last-flag, _-.But.•it wi11--take you back ta'flag.,DC26A. And.- so "should be Obvious From FLAB •DC54A, the bottom -.of the, second wetland, : -tae started- flagging'.again to : the. south ` down a'. relatively - narrow .- -corridor: Because this Para . of . tYie' . corrridor was. very di fficul,t to interpret; we. had: at. 1east one. false start with. flaggii- g.'that resulted'in._incorrect. flagging.", The. field notes - ndicate.'._thwe flags DC85 and DC86' should` be ignored:' -That implies that the.. narrow =` continuing: corridor flagging will. start with DC87 •-from edge ".point DC59A.:. -T_ hi.s corridor should.be definedas.a minimum of 6. feet. wide-on the .final.'surv.ey map.: 2 This-:1.111e of flags generally. heads SE. and'•eventually reaches a• currently used ' ai- t'. road• %at- flag DC97•.= _The. 'road-.,defin6s,. a narrow-. drainage corridor 'to -flag DG100. After DG3 00 , -'.the 'co'rrid'or' .vrideri§ again into. ae,tland that .covers the majority-of Block 14'. Due., to._ -very -dense -u iderbriish.,. ' it -was -not. possible. to accomplish: a -detailed- dellneatibn. of.=the wet -area -.on Block i.4.. The 'flagging along the north'. side: 'goes from £lag•'DC101A easterly.:;tnward.-the 'Eddy. Street. easement,; =to• flag ,:DC102A .` See the attiached conceptual -drawing for more detail .' ". about ahe' northern boundary.:= The :west side of .the;vretland extends:, southwesterly':from_ AC101B --to: ACJ.1B., = located :on Dscoveiy'.Aoad just west_ of, stake." marking --th@- Howard' •Street, easement `'- Pratri ig ,,a- Straight ;] ine -from .K102B to.: DC112B =is, pros abiy-:a good: first :esti:mate of the = westerly, wet1nd Boundary. - - - Due, to dense brush arid,., short sight. distance' ;, .a Fiore ;- detail6d•.delirieation would be '!Very - time = consuming -'and ahould: be undertaken by •tfie developer. [rowever : this- does' ixidicate" that :!t) e. northwest' ' 'corner , of Block 14. may _be'.upl -and:. - Ve . . do' ;not'.have enough - i:information'.to: eyal irate: "buffer, s+iidth, ; "butt _ h,e .wetland .on.- Block -l4 will -probably "-irate: as• a:Category III,..- "The--'' pei_'portibns. of the corridor rai17 probably ;_rate as Category We--had previousiy thought _t ie ;dirt. road. that: de'fi.Aes- -,,tire. drainage. corridor vial the,.-How' rd Street_; easement;: unit. it appears to actually be located somewhat east: of th6 -' easement.- at'' least. at its southerly - :_portion's ,near_ Block, _] 4.; Again; see, t'll attached dxavFing , i;or -elarificationY', BAS_IN_: BOUNDARY Thee .:recently~ updated topography/Iiasax:maps _show :the Howard: Street corridor as past of- .basin 11: However; 'in- field, it - .appears.. that 'instead the' _corridor drains: south `though :basin _36 - =' the ::aiasinssest :of 17:::._=,' There. _i s a wet area east of Fddy- Street and: s6uth; of - Disc- very- RoAdl That _ collects water from.: the cori dor:`_ _From that. wetland,.`..warer eouid drain- ei her:' nto bas ii Il' or''into. basin- i-&. topography' on top of _the .,zhal -Low. ti1T.::surface,- common. in the "-area' may,' wel 1- coritroT " direction. of flow:. Tnterpre.tatii,on .of surface topography. at. that point 1icywever' suggests `that - asin:7 b -ids a mare. 1i.kely:_ . recipient_ of surface 'flow: _The- only-.other clue about= -where: the water drains is in. the- relative depth -of. the two. basin - drainages to. the. south. - Basin.-ll does appear to- .be'but. deeper, suggesting higher_flow.volumes. But the sails At -the. southern end. of . basin-16 are deepier- and' .sazidi'er, - allowing more infiltration., more subsurface -, fl6y7, and thereby i'edticing, eras -ive farce.-of the__ _ grater. . In any event; .'.the.` boundary between_ these -two' drainages should- be checked .to' ' yerify 'direction_ 'of flow' ana. true .ba-sin perimeter: L .- assume that the basin maps are iri', tire., procesq, . beiztg.: checked and updated .through. Pol.ari.s :: Please .. forward this information to the - -approptiate' -party: SUMMARY The headwters`of. the, drainage: corridor are relatively high quality jurisdictional_ wetlands' that. appear to 'be -hydroibgically..isolated ft6m ea6h.- - other- (i,..e. there is :-no- surface hydrologic' connection)- .'.:They-.appear to-have' 3 I 1 Is© I 1 1 IR va or 11 , 11 I rr_aean I I 1 Is© 1 1 IR va or A iii 18 17 16 15 22 21 19 14 24 23 2 3 41, 10 2 8 91 10 ST 5 6 7 12 13 STRF 1 2 LO INO Vx 1 10 INI a. app LO INO Vx 1 10