HomeMy WebLinkAbout1998.05.29 - Wetland Mitigation Plan CT Pipeline Projectl' .; ,CITY OF PORT TOWI\ISENDWETLAND MITIGATION PLANCT PIPELINE PRO,IECTIApril1998Revised May 29,1998Prepared for the City of Port Townsend Department of Public Worksby Paula Mackrow, B.S. Earth Sciencesin conjunction with .CH2M IIILL, Bellevue, \ilAarnd Pacific Rim Soils and Water' Olympia' WAl.EXHIBITBrtili!
TABLE OF CONTENTSSUMMARYSEPA and OTHER PERMITSAPPLICANTREPORT PREPARATIONPROJECT DESCRIPTIONWetland NomenclatureECOLOGICAL ASSESSMENT OF WETLAI\D WL 16-02Delineation of ImPact AreaWetland RatingExisting VegetationExisting Water RegimeExisting SoilsExisting FaunaFunctions and Values:Position and Functions of WL 16-02 in the LandscapeWater QualityIMPACT Ai\ALYSIS OF'WETLAI\DS WL 16.02ECOLOGICAL ASSESSMENT OF WETLAI\D WL 16-01Delineation of Impact AreaWetland RatingExisting VegetationExisting Water RegimeExisting SoilsExisting FaunaFunctions and Values:Position and Functions of \ilL 16-01 in the LanflscapeWater QualifYIMPACT ANALYSIS OF WETLAIIDS WL 16.01MITIGATION APPROACH FOR WETLAI\IDS WL 16.01Goals and ObjectivesMitigation Measures \ iPROPOSED MITIGATION SITE FOR WETLAND WL 16-01Site DescriptionOwnershipNo.ageI'2,,2345566667788P8I99991011t212131313l41011Pt\ctpipe\wetmit9 8rev\Pjm-a-
ECOLOGICAL ASSESSMENT OF WETLANDSWL 11-01 and WL ll-02 14Delineation of ImPact Area l4Wetland Rating 14Existing Vegetation 15ETisting Water Regime 15Existing Soils 16Existing Fauna 16Functions and Values:Position and Functions of WL 11-01 and WL 1l'02 in the Landscape l7t7Water QualitYTABLE OF CONTENTS - Cont'd.Rationale for ChoiceWater QualitYIMPACT ANALYSIS OF WETLANDSWL 11-01 and WL ll'02MITIGATION APPROACH WETLAIIDSWL 11-01 and WL ll'02Goals an ObjectivesMitigation MeasuresPROPOSED MITIGATION SITESite DescriptionOwnershiPRationale for ChoiceWater QualitYBuffer Planting PlanWETLAI\D 15-01, WETLAIYD WL 11-01, AI\D WL 11-02PERFORMANCE STAI\IDARDSMONITORING PLAI\CONTINGENCY PLAi\Page No.t4t4t718181920202020202l2l2lt',24242425SITE PROTECTIONWetland WL 16-01Wetland WL 11-01REFERENCESPt\cBipe\wetmit9 8rev\Pjm-b-
TABLES:FIGURES:Figure 1.Figure 2.Figure 3.Figure 4.Figure 5.E)CIIBIT A:EXIIIBIT B:EXHIBIT C:TABLES AND FIGURESTable 1.Comparison of Impact and MitigationwL 16-01Table 2.Comparison of Impact and MitigationWL 11-01 and WL ll-02Table 3. Invasive Non Native PlantsTabte 4. Plants for Wetland and Buffer RestorationPipelinq Route with WetlandsSite Maps with propertY lineswL 16-01:Wetland A Generalized Planting PlanwL 16-01:\Metland Grading PlanWL 11-01 and WL ll-02Pipeline Details and Wetland Buffer Mitigation\iletland Reports:cH2M Irill,1992EES, 1992Pacific Rim Soils. and Waterrlgg3 andl994rl997City of Port Townsend, 1998comments from washington Department of 'wildlife, 1993 andDepartment of Fish and Wildlife,1994.Geotechnical memo, CH2M lfIILL,lggTEXHIBIT D:CT Pipetine Contract Specilications for Section 02200 Earthworkand Section 00400 Wetland MitigationEXHIBIT F: CT Pipeline Stormwater Site Plan Report' CH2M HILLI 1998Pt\ctpipe\wetmit9 Srev\Pj m-c-
CITY OF PORT TOWIISENDWETLAND MITIGATION PLAJYCT PIPELINE PROJECTApril1998SUMMARYThe City of Port Townsend proposes to build a new water supply pipeline in order to meetchlorine contact time (CT) requirements. This pipeline will supply water through 6,700 feetof new 24-inchpipe to the existing 5 million gallon reservoir and new standpipe within theCity of Port Townsend. Environmentally Sensitive Area (ESA) maps indicate that aquifert .L*g" areas and steep slopes exist in the proposed pipeline route. Wetlands have also beenidentified in the vicinity of the pipeline route. In consultation with the City of Port TownsendDepartment of Building and Community Development (BCD), it has been determined that anEnvironmentally Sensitive Area permit is not required for aquifer recharge or geologichazardous areas. However, three separate areas of wetland have been identified at thenorthern and southern end of the pipeline requiring evaluation and mitigation for the impactsof pipeline construction. Maintenance of storage capacity in frequently flooded areasur*ii"t"d with the northern wetland are addressed in the Stormwater Plan for the CTPipeline, March 1998 attached as Exhibit F.The pipeline construction will filt 1,500 square feet of wetland just south of Sims in theHoward Street right-of-way. Mitigation is proposed to create replacement wetland at a ratioof 2:l as required by the ESA Ordinance adjacent to the existing wetland WL 16-01.The pipeline construction will temporarily impact an estimated 3,300 square feet of bufferalong iloward Sfieet at wetland V'lL 16-02. This area is a grass lined swale that will berestored to its existing condition.The proposed construction will impact an estimatea g,SOO square feet of wetland buffer in theRainierbtreet right-of-way from l6th Street to 18th Street and 6,000 square feet in HowardStreet at Sims Way. This mitigation plan identifies measures to comp€nsate for the temporaryand permanent impacts of construction. The City proposes the following mitigationmeasures:1) lVL 11-01 and WL11-02: \ '. City purchase of.wetland and buffer property in order to avoid construction inwetland WL t 1-01 located at the north end of the proposed CT Pipeline route.. Revegetation to increase buffer values in the buffer areas highly disturbed by roadbuilding, grazing and clearing within the right-of-way. The City will replantvegetative cover in the construction zone associated with WL l1-01.2) lVL 16-01. City purchase of wetland WL t6-01 and buffer properfy east of Howard Streetsouth of 3rd Street at the southern end of the pipeline.Pt\ctpipe\wetmit9 8 rev\Pj m-1-
Buffer restoration and enhancement in the portion of the degraded buffer on Cityproperty and on the vacated 3rd Sffeet easement, with landowner permission.Restoration of the forested buffer in the Howard Sheet right-of-way south of 3rdstreet after construction by replanting a mixed age upland forest complex.Opening of Howard Street south of 3rd Street limited to construction of a gravelpipeline access road avoiding fuhue disturbance of the restored buffer area.The City has applied for street vacations for Howard ,3^,2no Streets and an alleyway encompassed by the property acquisition boundaries.3) !MT. 1.6-02; i. The City will avoid impacts to WL 16-02 through construction practices and useof BMPsThe City will restore the construction impacts of the degraded buffer alongHoward Street by hydro-seeding with native grasses.ooaaSEPA and OTHER PERMITSThe proposed project received a Mitigated Determination of Non-Significance in 1993amended in 1994.Other permits include Army Corps of Engineers Nationwide Permit #26 and Department ofEcology NPDES General Permit to Discharge Stormwater Associated with ConstructionActivities. Local Permits include Building and Clearing and Grading.APPLICAIYTThe project applicant and responsible party is the City of Port Townsend Deparfinent ofPublic Works, Robert L. Wheeler, Director. Robert LaCroix is the contact person.REPORT PREPARATIONDelineations were performed by Pacific Rim Soils and Water, LisaPalazzi, Principal. CH2MHILL has provided the stormwater planning, construction design and engineering. This planhas been prepared by Paula Mackrow for the Department of Public Works.aPt\cpipe\wetmit9 8rev\Pj m2-
PROJECT DESCRIPTIONThe City of Port Townsend Water System CT Compliance Pipeline project runs from thesouthern limits of the City of Port Townsend at the Olympic Gravity Water System controlvalve site in Howard Street along the unopened easement for Howard Sheet north to 1OthSteet, northwest across Discovery Road then along the Rainier Sheet easement fromDiscovery Road to a point 200 feet north of 16th Sneet, northwest to Tax Lot I of T30NRIW Section 9, west and northwest to the reservoir and standpipe site. The entire proposedroute is illushated on Figure 1.The project consists of a buried water supply main conveylng fieated domestic water to theport Townsend water system at the Howard Street resewoir site. The pipeline constructionwill require a minimum excavation width at the top of the fiench 6 feet or wider for trenchwall stability. The overall width of construction impacts along the pipe route, includingequipment acc.ss, will be 30 feet wide in Environmentally Sensitive Areas and up to 45 feetwide along the remainder of the rciute, for a total potential construction zone of 6 acres. Apermanent wide gravel access way 10 feet wide will be constnrcted over the proposedpipeline to facilitate access to the pipeline for maintenance and repair. This roadway willierminate on Howard Street at the existing pipeline road at the southern end of the route andnear the City water tower on 20th Street at the northern end of the pipeline.The proposed route runs through upland forest and open field much of which is platted forresidential use and through some land designated in 1996 as mixed commerciaV lightmanufactgring, multi-family and community mixed use. Zoning in this area is designated forresidential densities varying from 4 to 24 dwelling units per acre. The majority of the routeis in dedicated street right-of-way or on City owned properly. It is largely rurdeveloped at thistime. Total new gravel access road construction will be 2,000 feet.Five wetlands have been identified along the pipeline route and are shown on Figure 1. WLll-02 is an extension of a broad flat drainage axea that initiates at WL 11-01 in Basin 11. Thedrainage crosses Discovery Road and eventually drains south possibly dischargrng into Basin16. WL 11-01'and WL I I-02 arc contiguous wetlandg likely associated through subsurfacehydrology forming a wetland system at the headwaters of a drainage corridor. WL 11-3 is asmall jurisdictional isolated wetland in a broad wet area between Rainier Sfreet andDiscovery Road. This drainage is highly altered from road constnrction and forest practicesand has occlurences of wetland (hydrophytic) plants and standing water in areas moreextensive than the delineated wetlands referenced in this study. The fourth wetland is inBasin 15. WL 16-01 is a small jurisdictional wettrand in the Howard Street right-of-way atSims Way. The wetland is associated withthe outfall of the storm water pipe that drains froma sub-basin north of Sims Way and the parking lot south of Sims adjacent to the wetland. Arecently identified wetland, WL 16-02, ritr io-u depression at the corner of Howard and 66Sfreets .The pipeline route is more than 100 feet from WL 11-3. The City is purchasing property to.avoii constnrction in WL l1-01. Buffer enhancement in this area is proposed as mitigationfor impacts to the buffer of closely associated WL 11-02 near where the buffer designationwould bverlap. WL 11-02 is outside the pipeline route, but some of the forested buffer will beimpacted by itre construction zone. WL 16-01 was delineated as a regulated wetland underthe Environmentally Sensitive Area Ordinance in October 1997. Some fill in the street right-Pt\ctpipe\wetmit98 rev\Pj mJ.
of-way is proposed as no other alternative exists for the pipeline route or state highwayintersiction aiignment at this point. No construction is proposed in wetland 16'02 howeverconstruction *ilt impact the buffer area. Restoration to existing conditions is proposed.The impacts from the proposed pipeline in WL 16-01 and in the buffer associated with WLlI-02 and 16-02 require Environmentally Sensitive Area permit mitigation. The proposedconstruction will temporarily impact approximately 14,500 square feet ofbuffer andpermanently impact 1,500 squa^re feet of WL 16-01. The proposed construction on Rainier'Sneet will iemporarily impact approximately 9,7 50 squaxe feet of buffer associated withWLl l-02 in the Rainier Street right-of-way. Approximately 2,100 square feet will bepermanently impacted by the maintenance road. Approximately 3,300 square feet of bufferwill be temporarily impacted in WL 16-02.The intent of the proposed mitigation is to use the wetland replacement ratios, bufferaveraging and buifer enhancement sections of the ESA ordinance. The mitigation plan willidentify areas of degraded buffer that can be enhanced with additional plantings, fencing andrr*ouul of domestic livestock. Filled wetland WL 16-01 will be replaced on site with createdwetland of the same scrub-shrub characteristics. While creation is not the preferred mitigationmeasgre for wetland fi1l, the amount of fiil is less than 0.1 acres, below the preconstructionimpact for the Army Corps of Engineers NWP # 26. Carcful site selection meetsrecommended parameters, the existing wetland area to be filled has no pretreatrnent ofstormwater which will be provided for the entire remaining and crated wetland. With theseconsiderations the proposed wetland creation wiil provide better wetland function over time.Wetland NomenclatureThe environmental review is based on wetland field work that began :ul.1992 prior to theadoption of the ESA ordinance by the City of Port Townsend . At that time the projectinciuded a similar pipeline to service the Tri-Area portion of the City water system. Thewetland identification proceeded specifically for design of these pipelines. This resulted inthe wetlands being "named" together in one initial reconnaissance by Greg Miller of CH2MHILL. Wetland.l was out of town near Four Corners Store. The potential wetlands in theCity limits were numbered from north to south along the proposed pipeline route. Thisproject review was not related to drainage basin analysis until later in the process during theig9+ a"fi.teation site work. At this time the northern most wetland, No.2 was noted to beadjacent to a previously unidentified wetland that together formed a coridor wetlandcomplex almost one mile long. The second wetland was named'T'[o. 2a". All of the previouspermit applications used this nomenclature and may be present in the exhibits attached to theESA mitigation plan. , .The City established a database for wetland identification and characterization subsequent tothese initial investigations. The nomenclature is now based on the identification of thewetland within a designated drainage basin. The City uses a specific basin bor:ndary map.This map may need to be amended in the future as basin boundaries in flat headwater areashave bein difficult to identiff and can be easily altered through even minor developmentactivities, especially street openings. This ESA mitigation proposal is the first document touse the City nomenclature regarding the CT-pipeline review.Pt\ctpipe\wetmit9 8rev\Pj m-4-
(Subsequent to publishing of the ESA Permit Notice the City identified the upsfream seasonalwater source oithe southern most wetland as a probable wetland. Review of that area hasbeen included below. This direct connection between wetlands adjacent to Howard Streetbetween 66 and 2nd Streets indicates that the basin boundary map is in enor. [n order toappropriately name the newly identified wetland, thebotrndary between Basins 15 and 16 hasU.rn uajutteO to include the whole system south of 66 Sfreet in Basin 16.For additional simplification in the mitigation drawings and documents, the wetlands aresimply referred to as A and B in the contract documents. The current nomenclature is shownin Figure 1. A summary of the change in wetland identification is provided below.Wetland BWetland Bwetarea@66 st.Wetland AwL 1l-01wL 11-02wL 16-02wL 16-01FormerlyBasin 15No. 2No.2A(a)No.4No.2Off-site drainagecorridorNo.4Rainier St. to HowardSt., north of 18th St.Rainier St., south of18th st.Howard St. at 6'h St.Howard St., south ofSims Wayspecs199819941992LocationECOLOGICAL ASSESSMENT OF WETLAND WL 16-02Delineation of ImPact AreaAs required in the Port Townsend Environmentally Sensitive Area Ordinance, adoptedOctober, L992,the 1989 Federal Manual for Identiffing and Delineating JurisdictionalWetlands was used to delineate the wetlands along the pipeline route. Field reconnaissancewas done several times in1992,'93,'94 (mostly spring and summer) and October'97 didnot reveal the presence of this wetland. The property owner has indicated that some timesince 1996 heiemoved a large pile of logging slash from the area. The adjacent street waspaved directing flow from the site into a swale on the west edge of Howard Sheet that drainsiirectly into witland l6-01. Hydrology in the form ofponded water was observed on the siteFebruary through April of 1998. The delineation was done by Paula Mackrow on May 19,199S. Tire delineation of the.disturbed area documents 90% hydrophyhc vegetation. Isolatedpockets of saturated soils remained on site but the evidence ofhydrology is based on theiecorded observations in February and March, 1998. Since the soils were highly disturbedacross the site, the presence of the other two parameters were critical to delineate the area asdescribed in the attached wetland memo. The site was subsequently delineated by Lisapalazzion May 26.Her field markings were somewhat more niurowly defined and indicatedthe presenc. of ftrqo"ntly flooded rather than wetland in some of the margins of the area. Itis piesumed to be jurisdictional with an area just above 5,000 square feet.Wetland RatingPt\cAipe\wetmit98 rev\Pj m-5
IAlthough wetland 16-02 is connected to other riparian and upland habitats, and is diverse inwetland type and vegetation, the wetland and its buffers have been impacted by urban streetdevelopment, logging, and grading as well as long term agricultural use to the north. Thefield rating done, in accordance with the Department of Ecology Wetland Rating Systemindicates it is a Category III wetland based on the limited size and extensive disturbance. TheESA Ordinance requires 50 feet of buffer around Category III wetlands.Existing VegetationWL l6-02 is a Palustrine Emergent/ Scrub-Shrub wetland. The predominant vegetation in thedisttubed emergent zone is veronica sp., grasses including Agrostis and Poa species with avariety of Carex sp. And Juncus growing at the edges of the areas of seasonal ponding. Thescrub-shrub component in the less disturbed area consists of Scouler, Hookers and Sitkawillow, quaking aspen and nootka rose. Mature willow and aspen dominate the overstorywith about 30% Douglas fir. Douglas spirea, and veronica axe conlmon in the area of greatestinundation. Spikerush, bluegrass, and young aspen are dominant in the pasture areas. Shallowswales in the pasture upstream are filled with creeping and meadow buttercup (Ranunculusrepens and airis). This northern edge is in the 6'h Street right-of-way, considered for futureopening in a preliminary short plat approval for the parcel containing the wetland.The buffers on two sides of this wetland have not been cleared and retain a densely vegetatedsalal willow shrub layer with douglas fir and madrona overstory buffers. The west side hasapproximat ely 20 feet of cleared area as buffer between the wetland edge and pavement onHoward Street, less than the25 feet minimum required in the ESAO. The pavement wasconstructed in 1996.Existing Water RegimeThe primary source of hydrology is seasonal stormwater that collects in the pasture north ofthe wetland and from the surounding upland forest. The hydrology has been altered with theopening of Howard Street intemrpting the through flow and outlet to a lower depression nearthe Jackpot Sation. Construction of this road likely blocked the natural drainage corridor thatwas initially intemrpted by the construction and culverting of Sims Way decades ago. Thiswetland overflows and seeps into Wetland 16-01 and on into a forested drainage corurectingto a larger drainage corridor to the west in Basin 16. The drainage appears to flow south intothe industrial yard of the Port Townsend Paper Company outside of the city limits beforeentering Port Townsend BaY.Existing SoilsAccording to the Soil Conservation Service; Jefferson County Survey, the soils on in thevicinity are mapped as Clallam series. In Port Townsend these map r:nits commonly containwetland inclusions where shallow soils less than 20" deep overlay compacted, slowlypermeable till. These inclusions are generally overlying a shallow cemented hardpan andhave a seasonal water table within6-12 inches of the surface. The slowly permeableunderlying till allows these areas to completely dry out in the late spring and early srunmer.Seasonal hydrology is difficult to observe, the soil colors are often marginal and uplandvegetation is associated with wetland plant communities establishing root zones on bermsand hummocks of forest debris just above the saturation zone.Pt\ctpipe\wetmit9 8 rev\pj m-6-
The soils observed in the main area of the wetland were highly disturbed. Layers of rottingvegetation and indications of charred debris are scattered at 0 to 12'in several places. The*utri* color of 2.5Y 512 and 2.5Y 4l2withdistinct mottles within 12" of the surfaceindicates formation in hydric conditions in the past or recently due to the localized drainagelimitations. At trvo pits sulfide odor was also present indicating the site currently hasreducing environment in saturated soil. Some wetland area was extensively graded in 1996 toremove logging slash. The soils in undisturbed vegetation show signs of burning and tillinggteater than 10".Existing FaunaThe area is home to semi-urban wildlife species common to Port Townsend including deer,coyote and a variety of small birds. There are no threatened or endangered species reported inthe area. The adjoining timbered properfy to the south and west retains second growth forestcover. Vegetative cover naturally reestablished since 1996 provides just less than .25 acres ofseasonal aquatic habitat although it is highly disturbed.Functions and Values:Position and Function of WL 16-02 in the LandscapeWetland V,lL 16-02 sits in a drainage corridor Howard Street right-of-way along the west.The wetland has been created as stormwater flows overland from upstream pasture land andis backed up by Howard Street and ponded in the flat across at the unopened 66 Street rightof way. The street development in the mid 1990's restricts the flow that appears to havecrossed Howard to the southwest near to a depression near the gas station.The site contains a Palustrine Scrub-Shrub/Emergent wetland complex of less than one acrethat includes a portion of the pasture to the north, and a higtrly disturbed, irregularly shapeddepression with emergent vegetation ringed by willow, aspen, blackberry, culrant and rose.Thi upstream water source north of the 6th Street right of way notes that spring runoffcollects in small depressions in the pasture that was observed to drain directly overland intothe northern edge of the wetland along.the fence line. These depressions were vegetated withpasture grasses and creeping buttercup. Areal photos and sensitive area maps indicate a seriesof these depressions in the pasture to the north.The wetland seasonally overflows and seeps from the street berm and flows in a swale then toa culvert under Sims Way providing the hydrology that now characterizes the lower wetlandWL 16-01. The area, zoned for intense commerciaVindustrial development, provides aremnant habitat link to another wetland, WLi5-02, west across the wooded parcel near theHilltop Tavern. WL 16-02 provides stormwater detention and teatnent, and some habitatqualities and open space that may become isolated through futtue development. Increasedimpervious surface in this basin will continue to change the hydrology of this and wetlandsupsheam and downstream in this subtle topography.This wetland and its buffer area provide a variety of functions in the landscape includingwater quality improvement, wildlife habitat, and flood attenuation. The existing forestedwetland buffers provide habitat for birds and animals that are considered to be wetlanddependent species and have essential life needs that can only be met in the adjacent uplandbuifer. Buffers provide shading, input of organic debris and coarse sediments, as well asPt\ctpipe\wetmit9 8 rev\Pj m-7-
providing room for variation and changes in natural sensitive area characteristics as will beneed in a rapidly developing area of the City.The existing buffer functions along Howard Street include stormwater conveyance,infiltration, water quality biofiltration though the existing grass swale. Some water qualityfunctions will be lost if the proposed short plat is required to widen the roadway and piperunoff directly under Sims Way. Screening and wildlife habitat are not functions of the eastbuffer along Howard Street. However, in the existing landscape, the system continues toprovide hydrology to the downstream wetland.Water QualityThe wetland and its vegetated buffers reduce impacts to water quality by controlling soilerosion, reducing pollutants from upstream grazing and road runoff, reducing watervelocities, and moderating water level fluctuations in the drainage corridor. This wetlandreceives water from a drainage sub-basin that is largely undeveloped pasture land.IMPACTANALYSIS / 6 - e^1--No construction is proposed within wetland WL 16-02. Constuction of the pipeline couldpotentially block flow of runoff from this wetland further altering the hydrology of the area.To avoid this potential impact, pipeline design inciudes trench plugs that will preventcaptured surface flow from running south in the pipeline trench.The buffer in this area is already degraded with about 25o/o of the buffer area paved alongHoward Street. The City of Port Townsend ESA ordinance allows stormwater systems in thebuffers if there is no reasonable alternative. The proposed constnrction will not reduce theexisting buffers on Howard Street and will restore the grass lined swale draining to theculvert under Sims Way.Although measures to avoid and minimize the impact to the wetland buffers from theconstnrction of the CT pipeline are included in the constnrction and design and revisions,5/98, some construction impact in the buff6r area is unavoidable. The city proposes to frenchand backfill in approximately 3,300 feet of buffer. In general, the buffer areas are currentlydisturbed and sparsely vegetated due to previous grading and filling. Increased erosion,possibly less infiltration capacity and longer periods of standing water could result withoutadequate erosion control, stormwater planning and replanting.Existing disturbed buffer area will be replanted in native wetland grass mix afterconstruction. Construction in the dry season is expected to minimize erosion potential andhydrologic impacts to this wetland and wetland WL 16-01 downstream. Temporary erosionand sedimentation controls are proposed in the Stormwater Site Plan Report, Exhibit F.ECOLOGICAL ASSESSMENT OF WETLAND WL 16.01Delineation of Impact AreaAs required in the Port Townsend Environmentally Sensitive Area Ordinance, adoptedOctober, 1992, the 1989 Federal Manual for IdentiSing and Delineating JurisdictionalWetlands was used to delineate the wetlands along the pipeline route. Field reconnaissancewas done several times in L992,93 and 94 (mostly spring and summer). The majority of thePt\ctpipe\wetmit9 8 rev\Pj m-8-
area wiui observed to be highly disturbed during the June, 1994 delineation. Only a smallportion of the wetland was delineated as meeting the three parameters at that time. Hydrologyias observed on the site during the next two growing seasons. The delineation was revisitedby palazzi and Kline in October, 1997 to include the area east of Howard Street. Thedelineation of the disturbed area documents 100% hydrophytic vegetation and hydrologypresent on the site. Hydric soils may not have established yet, however the presence of theother trvo parameters were determined to be adequate to delineate the area as described in theattached wetland rePort.Wetland RatingAlthough wetland 16-01 is connected to other riparian and upland habitats, and is diverse inwetland type and vegetation, the wetland and its buffers have been impacted by fill and.o*-"t iul development adjacent to the wetland. The field rating done in October 1997, inaccordance with the Department of Ecology Wetland Rating System indicates it is a CategoryIII wetland. The ESA Ordinance requires 50 feet ofbuffer around Category III wetlands.Existing VegetationWL 16-b1 is a Palustrine Emergent/ Scrub-Shrub wetland. The predominant vegetation in thedisturbed emergent zone is bentgrass, sp. with hardstem bullrrrsh growing in small openwater pockets that persists throughout the growing season. The scrub-shrub component at theedges consists of willow sp., red alder and nootka rose. Douglas spirea, soft rush, and.r..ping buttercup (Ranunculus repens) ring the eastern edge of the southern portion of thewetland and are common in disturbed sites.The buffers on three sides of this wetland have been cleared for commercial development orhave been impacted by the existing utility access road. The remaining forested buffer islargely in Howard Street right-of-way proposed for future opening to 3rd Sheet. The existingdegtaied buffer functions include infilnation, water quality, screening and wildlife habitatlosi. The existing utility easement road has reduced the buffer to less than 25 feet along theeastern edge.Existing Water RegimeThe primary source of hydrology is seasonal stormwater that collects on Howard Street northof Sims Way from a recently identified drainage in Basin 16 near 6th Street. Additionalstormwater to[ecting in the parking area south of Sims Way is discharged to the existingwetland in the narrow drainage corridor south of Sims. The hydrology has been alteredupsteam with the opening of Howard Street and manipulation of the outlet area thatsiasonally overflows onto the existing water line maintenance road. Construction of this roadand instailation of the Olympic Gravity Water System(OGWS) as the main water supply inthe 1920's likely blocked the natural drainage corridor though the roadway is culverted. Thisoutlet flows into a forested drainage that connects to a larger drainage corridor to the west inBasin 16. The drainage appears to flow south into the industrial yard of the Port TownsendPaper Company outside of the city limits before entering Port Townsend Bay.Existing SoilsAccording to the Soil Conservation Service, Jefferson County Survey,the soils on in thevicinity are mapped as Clallam series. In Port Townsend these map units commonly containwetland inclusions where shallow soils less than 20" deep overlay compacted, slowlyPt\ctpipe\wetmitg8rev\Pjm '9-
permeable till. The soils observed in the main area of the wetland were highly disturbed orfill material mixed and saturated to greater than 12" depth. The matrix color of 2.5Y 5/2 withdistinct mottles within 12" of the surface indicates formation in hydric conditions and couldreflect parent material from offsite or result from the localized drainage limitations. Upstreamsoils in the narrow corridor were identified in 1992 as having 10YR 3/1 soil color indicatinghydric conditions.The buffer and possibly some wetland area has been extensively filled south of the existingpavement. This unpermitted filIhas been poorly stabilized and is eroding into the wetland.The upper surface of the fill area is used for truck parking and as a refuse bum area. There isno stormwater control in the area of the fill.'Existing FaunaThe area is home to semi-urban wildlife species common to Port Townsend including deer,coyote and a variety of small birds-. There are no threatened or endangered species reported inthe area. The adjoining timbered property to the west was clear-cut within the last five yearsremoving the previous extent of mature forest cover. The remnant forest in the street right-of-way is not likely to provide the type of cover or structure required by priority species. Thewetland area was clear-cut and graded bare since 1990. Vegetative cover naturallyreestablished but the area remains highly disturbed with recent fill though the open waterareas have been relatively stable providing small pockets of aquatic habitat.Functions and Values:Position and Function of WL 16-01 in the LandscapeWetland WL 16-01 sits in a drainage corridor steeply headed by Sims Way fillto the northringed by parking lot construction, OGWS access road to the east and the unopened HowardStreet right-of-way along the west. The wetland has been created as stormwater dischargedfrom paved area is backed up and ponded in the flat platted land in Block 5. The wetlandseasonally overflows over the OGWS road. The area, sutrounded by intensecommerciaVindustrial development, provides a remnant link to the wooded areas south of theCity limits, also zoned for commercial industrial development. Protection of this area by theCity assures it will continue to provide stormwater retention and teatment, and some habitatqualities and open space that may become isolated through future development.According to the Washington State Department of Ecology guidebook for wetlandrestoration, functions provided by wetland buffers include protecting wetland functions andvalues, water quality improvement, wildlife habitat, and deterrence of human impact in thewetland. Vegetated wetland buffers provide habitat for birds and animals that are consideredto be wetland dependent species and have essential life needs that can only be met in theadjacent upland buffer. Buffers provide shading, input of organic debris and coarsesediments, as well as providing room for variation and changes in natr:ral sensitive areacharacteristics. These functions have been significantly impacted. However, in the existinglandscape, the system continues to provide protection to the downstream drainage corridor.That drainage is more steeply sloped than the project area, mostly undeveloped and heavilyvegetated to the city limits.Water QualityPt\ctpipe\wetmit9 8 rev\Pj m-10-
The wetland and its vegetated buffers reduce impacts to water quality by confrolling soilerosion, reducing pollutants from upstream grazing, road runoff and commercialdevelopment, reducing water velocities, and moderating water level fluctuations in thedrainage corridor. This wetland receives water from a drainage sub-basin that is largelyuntreated except for an oil-water separator at the edge of the gas station parking lot alongSims Way. This runoff drains directly into a nalrow runoff corridor in the Howard Streetright-of-way that forms the upper end of the wetland. This wetland channel proposed forfilling, provides the firnction of approximately 150 feet of biofiltration prior to discharge tothe emergent section of wetland. The buffers in this area have been degraded by removal ofnative scrub-shrub vegetation and replacement with mowed lawn that would function as afilter strip for the parking lot except that the pavement is sloped to direct all runoffinto twostorm drains. Additional field surveying in February, 1998 indicates these drains discharge todirectly to the narrow channel without treatment.IMPACT AIIALYSIS WETLAND WL 16.01Direct impacts to wetland WL 16-01 will be the filling of approximately 1,500 square feet ofwetland in the Howard Street righrof-way. Construction of the pipeline could potentiallyblock flow of runoff to the wetland altering the hydrology of the system. To avoid thispotential impact, pipeline design includes trench plugs that will prevent captured surface flowfrom running south in the pipeline trench. The filling of wetland in the swale will diminishthe water quality treatment the narrow corridor provides. This will be replaced with anadequately sized biofiitration swale to be created in the buffer area.The buffer in this area is already degraded with about 50% of the buffer area paved forparking lot and Sims Way. Wetland filiing and subsequent street development will result inthe removal of the buffeirequirement on idjacent commercial properties for 150 feet alongHoward Street. The created wetland would shift this buffer requirement south along HowardSfreet near 2nd Street on the same parcel. The City of Port Townsend ESA Ordinance allowsbuffers to be averaged for regulatory purposes. The City property pr:rchase will provideprotected buffer area for the created and existing wetland through buffer averaging. Bufferwidth reduction may be allowed as long as the buffer is irot reduced to a width of less than 25feet. The proposed construction will not reduce the existing buffers to less than 25 feet.However a proposed increased in parking adjacent on the wetland will reduce the buffer toone to three feet along 120 feet of existing pavement.Although measures to avoid and minimize the impact to the wetland buffers from theconstruition of the CT pipeline are included in the construction and design, someconstruction impact in the buffer area is unavoidable. The city proposes to fiench and backfillin approximately 3,500 square feet for a graveled access road in the Howard Street right-of-way. The area of impact extends approximately 550 feet south of Sims Way to theintersection with the existing OGWS access road.Existing disturbed buffer area will be used to create scrub-shnrb wetland adjacent to theexisting emergent wetland and to remove unpermitted fill for bank stabilization andreplanting. Additional buffer will be impacted by the constnrction of biofiltration swale andassociated bermed slopes. The total temporary buffer disturbance area is estimated at 14,500square feet. The swale design will remove two of the existing mature fir tees and provideto.k.ry protection to three othrrs. Five larger Douglas fir hees in the buffer area will bePt\ctpipe\wetmit9 8 rev\Pj m-11-
removed for pipeline construction. These trees are of an age, size, and form that couldprovide wildlife habitat. Other tees larger than 12" diameter in the construction zone will beretained. The forest understory will be temporarily cleared for constnrction equipment accessand trench excavation with potential for erosion and sedimentation. Construction in the dryseason is expected to minimize erosion potential. Temporary erosion and sedimentationcontrols are proposed in the Stormwater Site Plan Report, Exhibit F.In general, the buffer areas are currently disturbed and sparsely vegetated due to previousgrading and filling. Since the existing buffers in the wetland area are disturbed and lack densevegetation, long term impacts to the functional values in these areas should be improvedoverall by the proposed mitigation. lncreased erosion, possibly less infiltration capacity andlonger periods of standing water could result without adequate erosion control, stormwaterplanning and replanting. The project is seen as a net benefit to the water quality function ofthe buffer.MITIGATION APPROACHGoals and ObjectivesThe goals for this project are to compensate for unavoidable impacts to the wetland and itsbuffei by creatingieplacement wetland, replanting and restoring the affected areas impactedby construction of the CT Pipeline, while improving values and functions in currentlydegraded wetland buffer areas outside of the direct impact area. Environmental goals beyonddirect compensation, are to provide wetland enhancement on public properfy and to provideprotection of the existing wetland and buffer values for the long term.The objectives are:. to provide created wetland at a repiacement ratio of 2:lo to provide buffer impact compensation in relation to the permanent amount of impact.o to provide additional protection for wetland functipn and values by enhancing the buffer'svegetative density, planting native trees, shrubs and herbaceous species in the wetlandbuffer on both City and private property.. to increase the function and values of the disturbed area and created wetland by reducingthe effects of adjacent commercial development through buffer enhancement andadditional water quality treatment.o to enhance plant diversity by replanting with native seed, kees and shrubs found in thevicinity but not currently on this site.o to provide protective measures that protect the existing wetland and minimize impactsduring construction.. to remove or control non-indigenous plant species on the mitigation site over tirne asdescribed in monitoring report recontmendations.to document the viability of the created wetland and buffer restoration.aPt\ctpipe\wetmi t9 8 rev\pj m-12-
Mitigation MeasuresThis section describes the proposed planting plan, and best management practices. Moredetailed information on the planting plan is on the accompanying drawing: the GeneralizedWetland Planting Plan, Sheet 3, Figure 4 and in the Plant Materials List, with plantingspecifications, Table 4. The final drawings of the pipeline ffench, fill and access road beddingand stormwater and erosion control methods during and after construction are attached in theconfiact specifications, Exhibit D.The specific mitigation measures the City proposes are as follows:1) The City has purchased property described as Block 5 lots 9-13, portions of 8,14 NationalCity Addition, to protect the wetland on platted parcels from inappropriate developmentin the future.2) The City proposes to compensate for function and value loss by the proposed wetlandWL 16-01 buffer restoration:. Unpermitted fill will be removed.The wetland buffer vegetation to the north of the remaining wetland will berestored and enhanced with a diverse planting of native species in scrub shrub andforest communities.Construction impacts to the forested buffer will be mitigated through plantingsthat create a multi-aged forest and diverse understory.3) The City proposes to construct a biofiltration swale in the buffer area to provide waterquality treatment to the runoff from the sub-basin north of Sims Way including theexisting and potential runoff from the Wolcott property where no treatment currentlyexists or is proposed.4) The City proposes to create scmb-shrub wetland adjacent to the existing emergentwetland at a replacement ratio of 2:T or greater.5) The ESAO requires notice to title for the entire wetland and wetland buffer be filed withthe Jefferson County Auditor in a form approved by the City attorney prior to approval ofany development proposal.aa6) Short term BMPs will be used to protect the existing wetland and buffer areas fromimpacts by construction.PROPOSED MITIGATION SITESite DescriptionThe mitigation site is adjacent to the existing wetland and the CT pipeline route. The siteboundaries are the western edge of the Howard Street right-of-way from Sims Way to theexisting waterline easement road. This road forms the southeastern side of the site as far asnorth as the parking lot pavement at the edge of the 3rd Street rightof-way. This area isPt\ctpipe\wetmit9 8 rev\pj m-t3-
described as the National City Addition, Block 5 Lots 9-13 and portions of lots 8 and 14 asshown on Figure 2.OwnershipThe City has purchased the mitigation area except for the north half of the 3rd Street right-of-way. This area was vacated to the adjoining properly owner by ordinance in 1995.The owner has agreed to the wetland and buffer mitigation proposed on the private property.The Howard Street easement is dedicated from the National City Addition short plat and willnot be opened south of 3rd Street.Rationale for ChoiceThe site was purchased by the City to provide on-site mitigation for wetland creation,biofiltration and buffer restoration and includes restoration of an area of unpermitted fill inthe vacated right-of-waYWater QualityThe project proposes to improve the existing water quality in the wetland throughconstruction of a biofiitration swale that will provide treafrnent for stormwater run off thatcurrently discharges directly into the wetland. This swale wiii provide treatment andcontrolled discharge for run-off from an area that includes the entire sub-basin north of SimsWay. Properfy platting, street easements and proposed development off site are factors thatmay impact water quality functions of these wetland systems in the futrue. Bufferenhancement, stormwater nrn off control and infiltration improvements are oversized andmay mitigate some future offsite impacts in both drainage basins. This sub-basin is describedin the Stormwater plan for the CT Pipeline, Exhibit F.Removal of the unpermitted fill on the northern edge of the wetland, slope stabilization andrevegetation with native trees and shrubs will reduce soil erosion and sedimentation. Thebioswale and buffer restoration will benefit the water quality of the wetland replacing manyof the lost functions including shading, plant diversity, habitat improvement, reduction ofpotential pollutant input and moderation of fluctuating water levels.The created wetland will provide increased stormwater detention and erosion control with theimproved outlet as well as providing other wetland functions discussed above. Wetlandcreation in WL 16-01 is shown on the construction drawings. The wetland hydrology andbiofiltration design are described in attached stormwater plan prepared by CH2M HILL,Exhibit F.ECOLOGICAL ASSESSMENT OF WETLAI{DS WL 11-01 ANd WL 11.02Delineation of Impact AreaAs required in the Port Townsend Environmentally Sensitive Area Ordinance, Octobet, L992,the l9S9 Federal Manual for Identifying and Delineating Jurisdictional Wetlands was used todelineate the wetlands along the pipeline route. Field reconnaissance was done several timesin1992,93 and 94 (mostly spring and summer). The wetland delineation was reconfirmed inthrough additional field delineation in October, 1997.Wetland RatingPt\ctpipe\wetmit9 8 rev\Pj m-14-
Wetland WL 11-01 has been delineated and surveyed. Wetland WL l1-02 has beendelineated and surveyed along the westem edge. Both are shown in Figure 3. Both wetlandsare jurisdictional based on the 1989 Federal Method criteria and on size (greater than l/4acre). Wetlands WL 11-01 and WL 1I-02rate as category [I wetlands based on fieldevaluation done by Kathleen Mitchell and Lisa Palazzi for CH2M Hill on 6114/94 using theDepartment of Ecology Wetlands Rating System. There has been no significant change in thewetland, buffers or adjacent land use since 1994. The Port Townsend ESA Ordinancerequires 100 feet of buffer around category II wetlands.Existing VegetationThe large acreage west of the pipeline at the northern end is pasture land, characterized by15-20 year old regrowth following timber harvest. This site is proposed for short platting andmulti-family development in the near future. The future water fiitration site for the City ofPort Townsend adjoins the impact area which is also characterized by 15-20 year oldregrowth. To the east is densely pJatted land in forested wetlands from Discovery Road to20th Street, known as the Howard Street drainage corridor.WetlandsWL 11-01 andWL 1I-02areextensivelyvegetatedovermostoftheirarea. Thesewetlands are a Palustrine Emergent / Scrub Shrub / Forested wetland system, with a westernred cedar, red alder, and willow sp. hawthorne overstory. The understory is dominated bywild rose, Douglas spiraea, soft rush, sedge (Sciryrus sp.) and water parsley ( Oenanthesarmentosa). There are occrurences of non-native invasive species of thistle and blackberry inthe wetland and buffer.The wetland buffers along Rainier Street north of the existing &iveway near 16n Street havebeen logged within the past 20 years, more recently than the mattre forest overstorysurrounding the wetland complex. The western edge has also been grazed, compacted andgenerally dis.turbed in a marurer that impairs the function and values of the buffer. Thedegradation specifically effects the quality of the wildlife habitat, infiltration value andprotective screening to the wetland. The pipeline will be constnrcted in right-of-way some ofwhich has been impacted by vehicular use. While ther.e are some madrona and Dbuglas fir ofconsiderable size in the western edge of the buffer, the impact area is less vegetated with notrees over 6" diameter. The City has been able to design the route to avoid several large firtrees along the existing road, including one with a 36" diameter.Existing Water RegimeOriginal-ly identified as a wetland and a potential drainage corridor, wetlands WL l1-01 andWL 1l-02 appear to be two.distinct wetlands. The two wetlands are likely connected bysubsurface hydrology as they are less than 100 feet apart and separated by a berm or debriscaused by human disturbance. Together, they form the headwaters of a drainage corridorextending south-southeasterly to Discovery Road. The hydrology has been characterized aswater that collects naturally from surrounding uplands. It appears that the wetlands drain tothe southeast when standing water gets high enough to cause flow during the winter. The areis characterizedby relatively low relief and minor topographic differences between thewetland and surrounding uplands. In wetter than average years the wetland complex appearsto expand outside of its jurisdictional boundaries, flooding adjacent buffer and upland areas.The City is compiling an annual record of the fluctuation in water levels and periodic floodPt\cpipe\wetmit9 8 rev\pj m- 15-
r: ..zones in order to adequately identify areas to be regulated as frequently flooded areas andcritical drainage corridors.Basin information such as boundaries, size, and general hydrologic analysis are not complete.These wetlands appear to be at the northem most edge of Basin 11.Existing SoilsThe area that will be impacted by pipeline construction is outside of the delineated wetlandsand is characterized by upland soils with slopes less than l5%.T\e Clallam soils are the onlysoil type referenced in the SCS Soil Survey of Jefferson County within the project area.Clallam soils are classified as gravelly, sandy, loams, moderately well-drained and formed inglacial till. Average soil permeability is expected to be moderate in the shallow soils abovethe cemented till and very slow in the till layer'The Clallam soils originally develpped under a forest cover. Stormwater will percolate intothe soil readily in undisturbed areas but downward infiltration is limited by minimal soildepths. Water moves laterally across the till layer, surfacing in adjacent drainage ways andlow-lying areas and the soil is expected to be saturated periodically during the rainy seasonwhen the majority of the soil will percolate laterally toward the wetland drainage corridor.The upland and wetland soils appear heavily compacted on the former pasture area the Cityhas purchased, as well as in the Rainier Street easement north of the gravel drive.Although Clallam soils are not generally characterized as hydric, soils in wetland WL 11-01and WL 11-02 were considered as hydric inclusions most likely classified as Swanton serieshaving a generally gravelly sandy loam surface overlying a shallow cemented hardpan andhaving a seasonal water table within 6-12 inches of the surface. The most recent wetlanddelineation (Pa\azzi,1997) described the soils at 10 inch depth as very dark-colored (1OYR2/1) with an accumulation of organic materials over the mineral surface. The glacial tillsubstrate was slightly weathered in the top few inches and was described as cementeddepleted matrix (2.5Y 5/2 color) with mottles (2.5Y 4/6 color).Very little water is expected to infiltrate more than a few inches into the till. Thecombination of the unusually shallow till and minimal infiltration potential causes the soils tohave very little storage capacity, consequently making pending and flooding potential quitehigh following precipitation slightly above normal.This report also describes the adjacent upland Claliam soils as having soil colors similar tothose int the wetland but slightly yellower,and with few mottles. This indicates that there is asaturated zone above the till surface but that saturation does not persist as long in the uplandas it does in the lower area of the landscape.Existing FaunaA representative from Washington State Department of Fish and Wildlife visited the area in1994 and concluded that wetlands WL 11-01 and WL ll-02 and the mature forested bufferarea outside ofthe project area provide habitat for priority species such as pileatedwoodpeckers, band-tailed pigeons and nesting raptors. WDFW describes this mature secondgrowth forest habitat with mixed canopy of deciduous and coniferous trees as providing avariety of high quality habitat for songbirds, raptors, small mammals and deer. (T. Rymer,Pt\cpipe\wetmit98rev\Pj m- 16-
per. com., gl16194) This fype of forested wetland system is increasing in habitat value as itb"comes more scarce in urbanizing areas as discussed in written comment from WashingtonDepartment of Wildlife to the City of Port Townsend (9127193 andllll/94). Mr. Rymerconfirmed in personal communication April 1998 that the pipeline construction posed nothreat to this habitat or species using the forested area.Functions and Values:Position and Function of Wetlands WL 11-01 and WL ll'02 in the LandscapeWetlands WL 11-01 and WL 1 1-02 are category II wetlands forming the headwaters of adrainage corridor that extends through a gently sloping landscape platted for urban residentialdevelopment. "This broad flat drainage pattern combined with shallow soils results in therebeing a high potential for wetlands to develop in the area south and east of the site as roadsand homes are built, inadvertentiy cutting off or diverting historic drainage patterns."(L.P alazzi, November 1992).These wetlands provid.e stormwater retention and infiltration as well as providing a wildlifecorridor of diverse forest canopy in and between emergent and scrub-shrub wetland andupland habitats. While some of wetland WL 11-01 is owned by the City of Port Townsendon the future filtration site, the majority of this system is platted in 50 x 100 foot lots anddesignated street right-of-way. The mature second -growth forested buffers are noted on the1996 Land Use Map as part of a potential open space corridor providing important habitatconnections along the mile long drainage corridor.Water QualityVegetated wetland buffers reduce impacts to water quality by conffolling soil erosion,reducing pollutants from grazing, road runoff and garden chemicals, reducing watervelocities, and moderating water level fluctuations. It is anticipated that as the platted land isbuilt out and the street easements are opened in this basin, there will be an increase in theamount of runoff collecting in these wetlands. Future stormwater retention and biofiltationneeds of residential developmeni would amplify the value of the existing heavily vegetatedbuffer area.IMPACT ANALYSIS OF WETLAI\D WL II-01 AND WL 11.02No direct impacts to the wetland are proposed. The City purchased land to avoid constructionin wetland WL I 1-01. The City also purchased 100 feet of buffer and 30 feet of constructioneasement to minimize buffer impacts. Construction of the pipeline could potentially blockthe natural flow of runoff to the wetland altering the hydrology of the wetland system in theHoward Street drainage corridor. Geotechnical studies from test pits along Rainier Streeta-djacent to the pipeline trench indicate that excavation will be within the till layer. Pits to aaeptfr of 8 feet iii not find evidence of a more penneable layer in the excavation zone. Toavoid potential impacts to wetland hydrology, pipeline design includes tench plugs that willprevent captured surface flow from running south in the pipeline trench. Calculations of theimpacts of additional impermeable surface from the gravel access road shows that potentialinclease in run off volume in any sub-basin drainage area along the pipeline route will becontrolled by the design mitigation of swales, trench plugs and cttlvert installation.Pt\ctpipe\wetmit98 rev\Pj m-t7 -
Although measures were taken to avoid and minimize the impact to the wetland buffers fromthe conshuction of the CT pipeline, some conskuction activity in the buffer of Wetland WLll-02 is unavoidable. The City proposes to ffench and backfill approximately 9800 squarefeet of buffer, and permanently decrease the buffer by 2100 square feet for graveled accessroad. The area of impact is from approximately 210 ft north of the existing gravel road to120 feet south along the existing road.The City of Port Townsend ESA ordinance allows buffers to be reduced for regulatorypu{poses. Buffer width reduction may be allowed as long as the buffer is not reduced to a*iaUt of less than25 feet. The proposed construction would reduce the previously disturbedbuffers in some places to less than 50 feet, well within the regulatory requirement.The area of impact has little structural diversity with no trees over 25 ft in height. Some (6)larger Douglas fir trees are on the west side of the gravel road, but are no longer corurected tothe remaining buffer. These frees are of an age, size, and form that could provide wildlifehabitat though they are already separated from the wetland buffer by the road.. The pipelineroute has been changed to avoid removal of these trees.In general, the buffer areas are currently disturbed by gtazngor sparsely vegetated due toprevious grading. Since the existing buffers in these areas axe disturbed and lack densevegetation, long term impacts to the functional values to these areas should be minimal.Increased erosion, possibly less infiltration capacity and longer periods of standing watercould result without adequate erosion control, stormwater planning and replanting tovegetation density comparable to the existing conditions. The curent agricultrual use aspasture was removed in 1994 from the city owned buffer area. This is seen as a net benefit tothe water quality function of the buffer.MITIGATION APPROACH FOR WETLAIIDS WLll.Ol AND WL11.O2Goals and ObjectivesThe goals for this project are to compensate for unavoidable impacts to the wetland buffer byreplanting and restoring the affected areas impacted by construction of the CT Pipeline, whileimproving values and functions in currently degraded wetland and buffer areas outside of theAirect imfact area. Environmental goals beyond direct compensation, are to provide wetlandenhancement on public properly and to provide protection of the existing wetland and buffervalues for the long term.The objectives are:o to irovide buffer impact compensation in relation to the permanent amount of impact.o to provide additional protection for wetland function and values by enhancing the buffer'svegetative density with plantings of native frees, shrubs and herbaceous species in thewetland buffer on CitY ProPertY.Pt\cpipe\wetmit9 8 rev\Pj m-1 8-
o to increase the function and values of the degraded wetland by reducing the effects ofgr:u:r;rg and soil compaction.. to enhance plant diversity by replanting with native seed, Eees and shrubs found in thevicinity but not currently on this site.o to provide protective measures that minimize impacts dwing constuction.o to remove or control non-indigenous plant species on the mitigation site identified duringpost construction monitoring.. to document the viability of the wetland and buffer restoration.Mitigation MeasuresThis section describes the proposed planting plan, and best management practices. Moredetailed information on the planting plan is on the accompanying drawing, the BufferMitigation Plan, Sheet 11, Figure 5. The final engineering drawings and contactspecifications includes drawings of the pipeline trench, fill and access road bedding andsiormwater and erosion control methods expected to be in place during and after constructionin Exhibit F.The specific mitigation measgres the City proposes are as follows:1) The city has purchased property identified as Tax Lot 4l containing a portion of thewetlanil, 100 feet of buffer and 30 feet of construction easement. The pipeline route wasredirected to avoid directly impacting wetland WL 11-01 or its buffer.Z) The City proposes to restore approximately 1,250 square feet of a degraded portion ofwetland WL 11-01. A portion of wetland WL 11-01 and its buffer will be protected and enhanced withfencing, livestock removal, and replanting.. Four years of livestock remoyal has allowed natural re-establishment of a nativewetland grass-rush-sedge community in the areas that have been heavily alteredthrough pta;rng and comPaction.3) In order to provide compensation to thebuffer area pennanently disturbed by the pipelineaccess road, the City proposes to enhance the upland buffer area of wetland WL 11-01adjoining the City's slow sand filter site and a portion of buffer shared by WL 1l-01 andwL 11-02.The area available to provide buffer enhancement consists of two currentlydenuded strips, one is 40 feet wide along the fence line for 120 feet. The other is140 feet by 20 feet wide. This provides an approximate total of 7,600 square feetof buffer restoration on City property.oPt\ctpipe\wetmit9 8 rev\Pjm-19-
Temporary impacts to buffer vegetation due to pipeline constnrction will berestored by hydro-seeding in the Rainier Skeet right-of-way.. Temporary impacts to the vegetation in the construction zone along Tax Lot 41will be mitigated by planting of fir frees in the construction zone adjacent to thegravel access road.4) The ESAO requires notice to title be filed with the Jefferson County Auditor in a formapproved by the City aftorney prior to approval of any development proposal for areasidentified as wetland or buffer.5) Short term BMPs will be used to protect the existing wetland and some buffer areas fromimpacts by construction.6) To protect the existing hydrology of the wetland complex, kelch plugs will be placed at300 foot intervals along ifr. pipai"e rom the City parcel at 186 Street south along RainierStreet to Discovery Road.PROPOSED MITIGATION SITESite DescriptionThe propos-d mitigation will take place generally on site within the impact area of thepropir"d pipeline route as well as within other portions of the buffer and within a disturbed"o*"r of ttre wetland formerly used as pasture as shown on Sheet 11, Figure 5. This area isidentified as Tax Lot 4l and the Rainier Street right-of-way.OwnershipThe propoied mitigation site Ta,x Lot 41 has been acquired by the City of Port Townsend.Areas within dedicated unopened City right-of-way for Rainier Steet will be reseeded. TheCity owned parcel at the filtration site contains a portion of wetland WL I l-01 and its buffer.1'ne Cify ugtl.r to protect this area as an Environmentally Sensitive Area in compliance withthe City's ESA Ordinance.Rationale for ChoiceAreas owned by the City of Port Townsend have some certainty of long term monitoring, andrestoration maintenance through the Public Works Departrnent. The City has the ability toprotect the restored areas from incompatible development. Through City ownershipbpportqnlties may be created for additional wetland enhancement through long range arterial,stormwater and open space planning including provision for property purchases through avariety of City revenue and grant funding.Water QualitYA stormwat.t pl* for the CT pipeline includes use of BMP'S necessaty to avoid changes tosurface hydrolbgy or natual drainage and infiltration through the existing buffer areas ofwetlands WL 11-01 and WL ll-02. This plan is attached as Exhibit F.oPt\ctpipe\wetmit9 8rev\Pj m-20-
Property platting, street easements and proposed development off site are factors that mayimplct water quality functions of these wetland systems in the futue. Buffer enhancement,stormwater run off control and infiltation improvements provide mitigation some fuhreoffsite impacts in both drainage basins.Buffer Planting PIanThe City proposes to compensate for 4,500 sq. feet of buffer impacted permanently due to themaintenance road by restoring and replanting the buffer of wetland WL 11-01 and WL 11-02on Tax Lot 41. Scrub-shrub buffer areas now in pastue will be enhanced through theplanting plan. Recommended plants ar-e listed in Table #2. These are cofilmon upland speciesulotrg thJpipeline route. Douglas fir stock from 2'to 5'tall, roses, snowberry and salal will beplanftO inthe mitigation area. Additional planting will include but not be limited to Oregongrape, ocean spray, and sword fern, wild cherry and cascara.planting in the construction zone along the existing road in the Rainier Street right-of-waynorth "i tgttt Street will be limited to grass reseeding and include some new tree and shrubplanting in areas of construction disturbance.Replanting and reseeding will generally occur after pipeline completion along the excavationzone. Restoration began tn I994,prior to construction, with the removal of the livestock onthe purchased property. Some plant stock for buffer restoration may be obtained from theconstrrction zone and used for restoration projects on other City wetlands. Late spring andsummer plantings will require weekly irrigation for two to three years to be provided by theDeparhnint of Public Works. Best Management Practices, plant procurement, plantingprocedures, soil enhancement, and weeding requirements written into the specifications forthe landscaping contact are in Exhibit D.WETLAI\DS WL l6-02,WL 16-01' WL 11-01 and WL ll-02PERFOR]VIANCE STAI\DARDSThe proposed length of time for mitigation compliance is five years. This time period willallow for the planted and volunteer species to become established in the buffer planting area.Sunrivorship of tee and shrub species is expected to consist of 80% or greater coverage ofthe buffer. Sr.rndvorship will be determined druing the monitoring process and if 80% orgreater cover is achieved and the plants are healthy and vigorous, and provide mixed forestand scrub-shrub diversity, the wetland buffer mitigation will be considered successful.MONITORING PLAI\ \ .This is proposed as a draft monitoring plan for monitoring the mitigation in all wetland andbuffer areas along the pipeline described previously. The outlined activities are proposed tobe instituted annually to determine whether plant sundvorship and percent cover provided aresufficient to meet the performance standards discussed in the previous section. The City willsubmit for approval a final monitoring plan consisting of these activities. More detailedspecificationswill be provided in the final plan upon completion of the construction,ristoration and planting activities in October 1998. These will be documented as- built detailswith the final post-condition of the sites submitted with the final monitoring plan.Pt\ctpipe\wetmit9 8rev\Pjm-2t-
The monitoring program is proposed to begin dr:ring the first year following plant installationand continue for 5 years. Monitoring will be conducted by City or contract personnel asrequired by the ESA Ordinance or its successor.Elements that will be monitored include:. general condition of planted species;. per cent cover provided by tree, shrub and herbaceous species; ando contribution of volunteer species. appearance of non-native invasive species (See Table 3)post construction monitoring will be conducted during the mid-growing season (July orAugust) of each year to evaluate the condition of the plantings. Trees and shrubs will ber"*pt.a by general site inspections determining the status of the plantings (live, dead orstressed) ofeach plant. Percent cover ofherbaceous vegetation should be noted throughoutthe buffer planting. Five photo points in each restoration area will be established to documentplant growth as designated in the Wetland Buffer Mitigation Plan and the Generalizedwetland Planting Plan (see Figure 5, sheet 11 and Figure 4, Sheet 31)A summary report will be prepared annually and submitted to the City of Port Townsendplanning and Building Deiarnnent. The report will consist of a general description of thecondition of the planted area and management recommendations necessary to ensures*rvivorship and health of the restoration site. Occurrences of invasive nonnative plants fromTable 3 should be noted in the monitoring reports. A weed control plan to remove invasiveplants will be included in the monitoring report.CONTINGENCY PLANThe requirements of the City ESA ordinance state this plan shall include provisions to assurethat restoration or rehabilitation is performed in accordance with the contingency plan ifmitigation failure results within five years of implementation. The City proposes that fundswill be designated within the CT pipeline operation and maintenance budget to meet thecontingency plan costs.The Public Works Department will establish a $50,000 mitigation fund within the CTpipeline budget should the City fail to complete street vacations in the area of Wetland WLiO-Of . The money will provide funding to develop a mitigation program on other City ownedproperty. The new mitigation plan would be required to provide wetland and buffer*itigution of equal or greater function and value than that proposed in this plan. A map ofCiry-owned wetland sites has been submitted with this plan. A mitigation and planting planmelting the ESA requirements shall be submitted for approval prior to the conclusion of thePt\cpipe\wetmit9 8rev\Pj maa
two year time frame for the sfreet vacation. Planting and other restoration activity shall takeplace within one year of approval of a contingency submittal.The following city-owned properties have wetlands that could provide increased function andvalue:1. Evans PUD wetland area ( if acquired in forest corridor hade) buffer enhancementplanting,2. Larry Scott Memorial Trail buffer enhancement to minimize existing impacts of RailroadTransfer Span,3. Kah Tai Lagoon Nature Park property acquisition focusing along Kearney Street, or 19ftStreet or buffer enhancement at the inner pond and trail area,4. Golf Course pond wetland restoration and buffer enhancement,5. 35fr Sneet Park wetland restoration at heavily manipulated drainage corridor,6. Buffer enhancement at old pond near Lynnesfield Green,7. Levinski and Winona wetlands in the northern corridor enhancement through weederadication.The Public Works Deparbnent will also submit a contingency plan for each mitigationactivity in this plan first annual monitoring report. The ptrpose of this site specificcontingency plan is to discuss the alternatives that are available if the monitoring programindicates that the environmental goals of the project are not being achieved. Contingencyplans will vary.depending on which goals are not being met. A11 contingencies cannot beiotr.".n; however, any problems that occur would be determined through the monitoringprocess. An appropriate corrective action would be proposed at that time. Generally theseactions will include:replanting of any dead vegetation in the first year and additional replanting if densitygoals are not met over the following four yeaxs.ao increased maintenance that may includ6 additional watering and/or weeding and fencerepair.o additional protection to revegetated areas including increased fencing and more restrictedpublic access.o additional protection to established buffers to compensate for the length of completion ofmitigation if the density goals are not being met.Pt\cpipe\wetmit9 8rev\Pjm-23-
SITE PROTECTIONWetland WL 16-01No fencing is proposed at this time. Bollards may be installed at 3rd Sheet in the HowardStreet right-of-way to prevent motorized vehicle access into the wetland buffer. The Cityowned parcel that contains delineated wetland and buffer shall be dedicated as natural areawith reitrictions on futtlre use as per Port Townsend Environmentally Sensitive AreaOrdinance. This restoration plan is not intended to confer any special status with regard tolocal Environmentally Sensitive Areas regulation on adjoining parcels but does intend toserve as mitigation for future sffeet development of Howard Street through the intersection of3rd Sheet.Wetland WL 11-01The City of port Townsend will provide fences along the Scott property adequate to containlivestoct but not prevent movement of wildlife. Bollards will be installed at the bend in thepipeline route noiin the steet easement to prevent motorized access into ttre mitigation area.i.Ion-motori zed. naffis through the existing wetland will be routed around the wetland on theaccess road. The existing barbed wire fence will remain to protect the new plantings.Additional barbed wire iencing will be installed along the pipeline route across the purchasedpropertY.The newly acquired parcel and the portion of the Future Filnation Site that containsdelineated wetland and buffer shall be dedicated as natural area with restictions on future useas per Port Townsend Environmentally Sensitive Area Ordinance.Pt\ctpipe\wetmit9 8 rev\Pj m-24-
REFERENCESLiterafure CitedCowardin, L.M., C carter, F.C. Golet, and E.T. La Roe. 1979. Classification of wetlands anddeep water habitats of the United States. (FWS/OBS -7913I) U.S. Fish and Wildlife Service.Washington, DC.Port Townsend, City of. October, 1992. Sensitive Area Ordinance. City of Port Townsend,wA.U.S. Soil Conservation Service,1975. Soil Survey of Jefferson County, Washington. U.SDepartment of Agriculture. Washington, DC.Washington State Deparrnent of Ecology. l99l.Washington State Wetlands Rating Systemfor Western Washington. Publication#9l-S7. Washington State Department of Ecology.Olympia, WA.Washington State Deparft:aent of Ecology. 1993. Restoring Wetlands in Washington.Publication # 93-17. Washington State Department of Ecology. Olympia, WA.Washington State Deparhnent of Ecology .lgg4. Guidelines for Developing FreshwaterWetlands Mitigation Plans and Proposals. Publication # 94'29. Washington StateDeparlrnent of Ecology. Olympia WA.Washington Departrnent of Ecology.1997. Washington State Wetlands Identification andDelineation Manual. Publication #96-94. Washington State Department of Ecology.Olympia, WA.Washington State Deparhnent of Wildlife. Letter to City of Port Townsend from Tim Rymer,September 27,1993.Washington Department of Fish and Wildlife. Letter io City of Port Townsend from TimRymer, November l, 1994.Cooke, Saratr Spear, ed. 1997. Wetland Plants of Western Washington and NorthwesternOregon. Seattle Audubon Society and Washington Native Plant Society, Seattle WA.Personal Communication: 1 'LisaPalazzi, Pacific Rim Soils and Water 94,97,98Mark Bentley, Deparhnent of Ecology,1995Tim Rymer, Deparhnent of Fish and Wildlife,9116194,4130/98Pt\ctpipe\wetmit9 8 rev\Pjm-25-
(Table 1. Comparison of lnpact and Mitigation AreasTable 2. Comparison of Impact and Mitigation AreasTable 3. Problem Species9,000 sf45,000 sfPurchase Area wl Right ofWaYand Easement10,000 sfRestoration in Construction Zone3,200 sfcreation12,000 sfunpermitted fill areaRestoration for Mtigation1,500 sf3,500 sf2,500 sfpermanent Tmpacts- right-oflway- bioswalenone14,500 sfTotal Distrubed Area forConstiuctionWETI"A}[DBIITTTR-oActivity WI--1250 sf26,900 sfPurchase Areanone4050 sfRestoration in right-oFwaylimited to resee,lingnone7,600sfRestoration out of right-oflwaynone2100 sfPermanent Impactsnone9750 sfConstruction ImPactsWETI"AIYDBI]TTERll -ot ll-ozActivity WLf and WL2p(esent WL 15-lreed canary gasspresent WL 11-1Canada thistlepresent WL 11-1Himalayan blackberry0ccurrenceInvasive Non-Native PlantsPtbtpipo\wotmi98a\Pjm-24-
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