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August 25, 2014 Mrs. Vanessa Dolbee Current Planning Manager Department of CED City of Renton Renton City Hall -G'h floor 1055 South Grady Way Renton, WA 98057 ..c-F.AVANA ~TR.AILS Re: Fieldbrook Commons Cul-de-sac Mrs. Dolbee UJA !3 -oo i I Ci CITY OF RENTON RECEIVED AUG 2 5 2014 BUILDING DIVISION Please find enclosed three copies of the proposed cul-de-sac planting plan for the center island in SE 172"d Street. We chose to utilize plants already in the overall planting plan for landscape continuity. These are low growing plants and grasses and should not obscure any sight triangles from the various entry/exit points. Thank you for consideration ofthis request, please feel free to contact me with any additional questions or comments. _:.~ely,) c: ,,/ ~-~ ~ers -- Avana Trails, LLC Avana Trails, LLC Business Office 9675 SE 36'" Street, Suite 105 Mercer Island, WA 98040 P: (206) 588·1147 F: (206) 588·0954 Sewall Wetland Consultin Inc. PNW HOLDINGS LLC -FIELD BROOK COMMONS CITY OF RENTON Sewall Wetland Consulting, Inc. 27641 Covington Way SE, #2 Covington, WA 98042 MITIGATION PLAN 3-13-2014 NWS-2012-1281 Prepared For: PNW Holdings, LLC 9675 SE 361h Street Suite 105 Mercer Island, Washington 98040 Attn: Justin Lagers March 13, 2014 Job#ll-21 Phone: 253-859-0515 Fax: 253-852-4732 PNW HOLDINGS LLC -FIELDBROOK COMMONS CITY OF RENTON 1.0 INTRODUCTION MITIGATION PLAN 3-13-2014 NWS-2012-1281 This report describes the proposed wetland mitigation for the Fieldbrook Commons PUD project, located on the east side of Benson Road South, and north of Cedar Avenue South (SE 172nd Street) in the City of Renton, Washington (the "site"). 2.0 PROPOSED PROJECT & MITIGATION SEQUENCING The purpose of the proposed project is to construct a multi-family apartment complex as the property has been zoned for, as well as planned for in the City of Renton Comprehensive plan. The need for apartment units within Renton is high and this project has been proposed to meet that need. The proposed project is the construction of a 161 PUD project with associated infrastructure. The location of Wetlands D, E and F result in most of the developable property on the site being encumbered by wetland or buffer. Since these wetlands, particularly Wetlands E and Fare of low value, and Wetland Dis small in size but because of its linear shape impacts the sites usable space so greatly, we are proposing filling these three wetlands. As a result, it is our intention to fill these wetlands and provide adequate mitigation for their lost functions by creating wetland on the eastern side of the site in and around Wetlands A, Band C. Impacts to wetlands must be justified through a mitigation sequence as detailed in City of Renton Code. Ideally we would be able to use the King County fee mitigation banking process as is preferred by the Corps and W ADOE. We are in agreement that using the fee-in-lieu mitigation option would be ideal and the easiest/fastest way to mitigate the proposed impacts. However, the City of Renton has refused to let us use this as a mitigation option as it moves the mitigation area outside the City limits and in their opinion is a net loss of critical areas to the City. It appears the City looks at the mitigation, and trail through the buffer as part of the "public benefit" aspect of this project. The construction of the mitigation onsite, as well as the placement of a trail through the buffer are being required by the City to allow us to construct this • Pieldbrook/# 11-121 Sewall Wetland Consulting, Inc, March 13, 2014 Page 2 project. It is our opinion that the trail does increase the amount of human intrusion into the wetland, and would be best left off the plan, However, the City of Renton will not accept this and are forcing us to bring a trail through the buffer regardless of the logic. The next best option is on-site replacement of the wetland area and functions as proposed in our mitigation plan. The attached mitigation plan has been prepared with the recommended documents elements as requested by Suzanne Anderson of the US Army Corps of Engineers in previous comments. This plan is prepared in the exact same manner and with the same information as numerous mitigation plans we have submitted and had approved by the Corps for various Nationwide as well as Individual Permits. As requested the monitoring has been modified to include I Oyears of monitoring. (c) Per the Federal Mitigation Rule, you must provide additional infonnation to document that a watershed approach to compensatory mitigation was used for the mitigation plan [33 CFR 332.3(c)]. A link to Wdland Mitigation Situ Using a Watershed Approach, Ecology Publication #09-06-032 is available from our webpage at www.nws.usace.army.mil, select "Regulatory Branch, Permit Information", then "Mitiption Resources", then "Mitigation Tools". We recommend that you dcmonstratc that the chosen mitigation site satisfies criteria in Charts 2 and 3 of the site selection guidance (i.e., identified as a site with potential and that is sustainable); and that it satisfies criteria in Charts 4 through 11 for the appropriate fimctions. Using Chart 2 from the Watershed approach which is an analysis utilized to pick a mitigation site is not really applicable, as the City of Renton is requiring we conduct the mitigation on the site where the impact is occurring. In addition, there is no other available mitigation sites within this drainage basin that is owned by either the City or the client for use as a mitigation receiving site. Therefore, mitigating on-site is the only feasible alternative given these constraints. In regards to Chart 3; Question 3A: Identify the watershed processes that have been altered within the hydrologic unit where the mitigation site is located. Human activities can change watershed processes by changing water flows; introducing nutrients, pollutants, non-native species, and sediment; and by fragmenting habitats. Changes in these processes often create problems that can be improved through mitigation activities. To begin you need to identify the major landscape-scale problems (i.e., alterations to processes, not structure) that exist in the hydrologic unit where your site is found This will help you identify which restoration or enhancement actions will be the most effective in that hydrologic unit. Check the appropriate column in the following table to identify problems that might exist. The last column notes if the altered process has already been identified in an existing watershed plan as a problem that needs to be addressed Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. March 13,2014 Page 3 The current flooding events within the Soos Creek drainage are generally not increasing due to the current use of modem storm water facilities within the basin. However, there still is some increase as there is more water getting to the basin faster in storm events. There is less eutrophication in rivers and streams in the basin primarily from removals of livestock and old septic systems. Water quality has been reduced in the basin to a degree. Some stream and bank erosion does occur within the basin. Habitat has become more fragmented as the area's population grows and more development occurs. Question 3B: Will the mitigation result in a wetland of the appropriate hydrogeomorphic (HGM) class for the landscape setting? Wetland mitigation sites are sustainable only if the type of wetland being proposed is appropriate for its position in the landscape. The HGM classification of wetlands is based on characteristics of water movement and position in a landscape. Therefore, it can be used to identify appropriate wetland types for different locations in a hydrologic unit. Yes, we will be mitigating for depressional wetlands with a depressional wetland mitigation area. Question 3C: Will the primary source of water to the mitigation site be appropriate for the HGMclass? Groundwater and direct precipitation will be the source of hydrology for the wetland mitigation site as was the source for the impacted wetlands. Hydrologic monitoring of the mitigation site has shown that surficial groundwater elevations in the mitigation area will sufficiently hydrate the creation area with soils saturated to the surface and some standing water in the growing season. Question 3D: Will the site have an adequate supply of water to maintain a wetland without engineering the delivery of water that would require long term control or maintenance? The surficial groundwater monitoring and proposed grades should create a wetland area that will require no additional or artificial source of water to maintain its viability. It is thought that Wetland A which is located within the area ofan old mine is discharging water from historic mining and as such there is an abundant supply of water in this area. Question 3E: Will the mitigation activities maintain hydric soils, if they exist, at the site? Removing hydric soils can decrease the potential for success of wetland restoration. Hydric soils often contain a seedbank of wetland plants that supplement any planting you may propose. Field brook/# 11-121 Sewall Wetland Consulting, Inc. March 13, 2014 Page 4 Hydric soils from the filled wetlands will be mixed with topsoil and utilized in the newly created wetland maintaining viable seedbanks. Question 3F: Can the mitigation be designed to control aggressive plant species? There is currently not a predominance of aggressive invasive or weedy species in the area of the proposed mitigation or the two wetlands that will be connected together with the creation. Standard invasive species control will be utilized in the mitigation area which has proven successful in other mitigation sites. Regarding the appropriate Charts 4-11; Chal't 5: <:nJal -lwproYiug Hydrology Fundiom iu Depres~ioual 5ystt'-tm Outsidt' of Flood1>laios ~--.. .. ... •• .. • ...,..,... .. ~ Ma',IIN~to....-"'*Ololie Metioa, lUT ,.. -i...,..IIIIW~lt .. lllldaelpt «* •ill IN -ilO to Md .,ntiln,l ,.dil(lln ....... -'~ :Rrlaiat. kl'IOI: .... ,.__, lltlaQl'ldllM<lllfflel'. i .. -npt.--J Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. March 13, 20 l 4 Page 5 Ch,irt 7: Goal~ Imprnving,\·at~r Quality ("-Q) Ftm<'tiom in Dep1·es<;ional .Sy~tNm Outi;icte of floodplain,;. -.. .;·eersr·_'zt~ Cal .............. ,. ---.. -.. ( linrl HI: Goal -hnprolillg SpE-cies Ridme,s of Wildliff-~...,..._ ... ~IP . ., ,,-:.·'·- -~ • • ... --_ ... .. ... , = .... .. .. ... Slll'fxe po,tdina: wil itllpKt the lfbutlutioR .t pllMS • '1M In (sa lo llelCt question I Ch.iri] 1: (nJal -Impro\ing Spl'des Rkhnes;; of Plants -- .-,.. -. ···-n> ' ,. ,. Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. March 13, 2014 Page 6 .. ., . .,.... ......... _ ~~= 5U,a,lt, auT e,ian •ust daolbl !low COMlt..Uat ltte ~ ,cai. wtlN.-...ci. (Flo Mn .,.nion) ' ...... ..... ·-~""""9fft.__iaqi......,;, ..... IIMl!lwriltltlew~-"'-"ffil; .. . ..._; ... _....,,._, ...... .....,..,._ .... --;-~. ::.-::::.-:.:.z. 1 ... .... .. This sequencing requires addressing the following criteria; a. Avoid any disturbances to the wetland or buffer; ~-. ~ ,_,.-... ffl'.i'lilla ... ,,.,.,,..-,...1 e-1e1..,._....,. ... .,_,,. iocl,..,_......,.,_ics __ , 1'9Ml'-IMrlwi-.-...-....""11d,i .... Nl'li •. a..a ... ........i. tt.~ ~ JNIIIIIII N-.nlladil!l fllaM .. ... r1y-,..;.,...1 .... ,tt..t .... --,.. ................. ••-t11'*"9n) ··--~ta,...iid.+....lnl -Nllalls,Klas•;t ... Niv,tln1-. ""' I ... ""'" 'llril~ I hip, l,ecill rilllM:11 ...-~~-1N1Mftsilot.LM ~.iPoNi,e,ityN ~SI.CUISl..u/ ==._~::..,,~·=::: -- The site contains three small wetlands which the developer proposes to fill and mitigate for through the creation of a new wetland area and enhanced buffer areas for the existing and remaining wetlands A, B & C in the eastern third of the site. Wetland F located on the western side of the site is Category Ill wetland measuring l 595sf. Due to the requirement to provide a secondary fire access directly out to I 081h Ave S.E. the developer is unable to avoid direct impact to this wetland. Wetland E, located in the center of the site and adjacent to S.E. l 72"d St. measures 68sf and is rated as a Category IV wetland. Due to the requirement to dedicate and construct the other half of the S.E. l 72"d St. ROW the developer is unable to avoid direct impacts to this wetland. Wetland D is located generally in the center of the project and is rated as a Category III wetland measuring 7671 sf. b. Minimize any wetland or buffer impacts; The developer previously attempted to plan roadways and improvements around Wetland D, however the location and shape of the wetland impacted the vehicular circulation and Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. March 13, 2014 Page 7 building locations to such an extent that the project would not be financially feasible to construct. c. Restore any wetlands or buffer impacted or lost temporarily; and Restoration of Wetland Din this location would not be feasible due to the location of the impacts and configuartion of the parcel and remaining wetland. d. Compensate for any permanent wetland or buffer impacts by one of the following methods: i. Restoring a former wetland and provide buffers at a site once exhibiting wetland characteristics to compensate for wetlands lost; This is not applicable to this site as no historic wetlands are located on the property. ii. Creating new wetlands and buffers for those lost; and A total of9,334sf of wetland will be filled. US Army Corps of Engineers Required Mitigation Using the recommended ratios from Table 1 a, of the W ADOE Publication Wetland Mitigation in Washington State Part 1, (WADOE March 2006 Pub. #06-06-01 Ja) Table 1 Wetland Size Category Vegetation Ratio Required Type Wetland Creation D 767 lsf Ill Forested 2:1 15342sf E 68sf IV scrub-shrub 1.5:1 102sf F 1595sf lll scrub-shrub 2:1 3 ! 90sf Total 9,334sf 18,634sf As described above, based upon the required USA COE and W ADOE ratio, a total of 18,634sfofwetland is required to be created. Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. March 13, 2014 Page 8 The proposed mitigation will create 25,430sf of wetland, which exceeds the required USA COE ratios by 6, 796sf. The extra wetland being created over the W ADOE recommended ratios is a result of the City of Renton having a higher mitigation ratio requirement than the Corps. As seen in Table 2 below, using the three main functions from the W ADOE Rating System recognized by the Corps, a substantial functional lift will be attained from the connection of Wetlands A and C with 25,430sf of additional wetland over the existing functions of the proposed fill wetlands. Table 2. Functional Comnarison of imnact wetlands and nronosed miti ation Wetland Area Flood Species Water Hydrologic Habitat Storage Richness Qual. Function Function canacitv Function Category Wetland D 7671sf 3800cufi 5 svecies 12vts 8nts 13vts III Wetland E 68sf 34cufi 2 snecies lints 4vts IOvts Wetland F 1595sf 500cuft 5 svecies 20vts 8vts 11 vts Pronosed 25430sf 7600cuft 15 species 24ots 20pts 21 pts Functional +16096sf +3266cuft +8species* +9pts +12pts avg +9pts l Lift av2 av2 *only 7 different species were found (excluding exotic/invasives) in Wetlands D, E &F The newly created wetland will connect to existing Category III wetlands (Wetlands A and C) and provide enough lift that this wetland will now be considered a Category II wetland under the W ADOE rating system. This is a substantial lift in function, surface water storage and species richness over the fill of Wetlands D, E & F, which are generally low value Category Ill and IV wetlands. Hydrologic monitoring of mitigation site and general construction overview IV III II +1 Cate2orv To compensate forthe impact to 9,334sfofCategory III & IV wetland, we will create 25,430sf of wetland between Wetlands A and C. This results in an overall wetland mitigation ratio of2.72:l (createdwetland:impactedwetland). This mitigation will create Category I! wetland for a combination of Category Ill and IV wetland impacts. As depicted on the attached Final Mitigation Plan, 25,430sf of area will be excavated out to a similar depth to the existing wetland in two areas to intercept the surficial groundwater table and create conditions favorable to create wetland hydrology. A series of 6 monitoring pits/wells were located within the proposed wetland mitigation area. These were monitored with weekly site visits from April of2012-August 2012 as well as March and early April of 2013. At each of these points soil saturation and water table levels were measured to determine what surficial groundwater elevations are, to facilitate designing grades for the new wetland creation area. What we found was that within the proposed creation area, groundwater levels in the early growing season area Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. March 13, 2014 Page 9 between 14" -30" below the existing surface (see table below). It is assumed in the very early growing season (February and March) the groundwater elevations are shallower than the measurements we took, meaning the groundwater elevations are closer to the soil surface. As shown on the attached Final Mitigation Plan Sheets Wl -W3, we utilized these existing groundwater contours to create the new grades for our mitigation site. As can be seen by the grades and associated cross-sections, the grades will remove soil down to the existing groundwater elevations to create wetland areas with soils saturated to the surface for the early growing seasons, to also include flat areas that will hold some shallow l "-3" of surface water to provide a variety of wetland hydro logic regimes from saturated, to seasonally flooded. The fact that the excavation is being brought to the higher levels of groundwater within the growing season, and will not cut into the surficial groundwater table, should alleviate the concern of intercepting and draining off this water. All we are doing is removing the surface soil above the existing sloping groundwater table to make those saturated soils closer to the surface. Soil disturbance of the groundwater retaining portion of the soil column will not occur. Although creation of a slope type wetland is not the most conventional or common mitigation method, it is a feasible method of wetland creation when conditions warrant its use. Our company has been involved in two larger wetland creations using this type of concept, most recently a 3 acre wetland creation with over IO' of vertical drop across the landscape in sloping of the creation area (see Snohomish County Parks Centennial Trail II mitigation plan reviewed and approved by Jonathan Smith of the Corps). By using the same method of removing soil down to the level of the highest groundwater elevations as is proposed in the Fieldbrook project, we successfully created a 3 acre sloping wetland in the previously described project. Table 3. Groundwater elevations below surface o ,. hvdrolo· "monitorinP noints 2012 Monitor DATE point& elev. 4/13 4/27 5111 5/24 617 6/28 7/12 A417.5' -15 -14 -15 -20 -26 drv drv B418' -17 -16 -16 -22 -27 drv dry C417' -20 -18 -17 -20 -25 dry drv D416.5' -14 -14 -14 -16 -20 drv drv E418.5' -27 -26 -24 -30 -36 dry drv F418' -21 -22 -20 -28 -36 drv drv Note: All elevations indicate the elevation of the saturated capillary fringe of soil saturation observed in hydrology monitoring points. 8/12 drv drv dry drv drv drv Table 4. Groundwater elevations below surface o Monitor DATE point& elev. 3/15 3/29 4/9 A417.5' -12 -I 0 -15 B418' -15 -15 -14 C417' -17 -16 -18 D416.5' -10 -11 -13 E418.5' -23 -20 -23 F418' -18 -19 -20 Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. March 13, 2014 Page 10 r hvdrolo• "monitorin2 points 2013 Note: All elevations indicate the elevation of the saturated capillaryfringe ofsml saturation observed in hydrology monitoring points. . . . . . . ,,. . . . .. . . : : : : : : : : : : ;;:: ~:::::::::. • 0 • 0 • + • I ' + • + J',A• • + • ;.:·, • 0 ' o O + + o o .. . ............. · .... /'.. . . . ... ••••••••••••• t ••••• • .. ~ ••••••••••• Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. March 13, 2014 Page 11 419A~~~__:__;W'---~~-EnsM~· _$,,.,_'"-ifa<,~~~~~~~~~--=;B lli~I ~~~~~t~~~~...,~.;J,~~~s.~~~~~~~~~~~2~~~~1 41 41 41 41 41 41 41 411 8A 7 6 5 4 2 w E.ristmg ,urfa« '\ -- J Pr.--..1 htU.I cw!UW D ' / '\ ', '\ ' '\ ' '\ '' ~ A small berm will be placed between the wetland creation area and Wetland B. This will prevent (in the unlikely case of surface water overtopping the edge of the wetland) the wetland creation area between Wetlands A and C from draining into Wetland B. Hydrologic monitoring will be conducted using peizometers in the proposed mitigation area through the winter and spring to verify groundwater elevations. This area will then be graded back at a slope no steeper than 3:1 (horizontal:vertical). The area will then be planted with a mix of native trees, shrubs and herbaceous species and will also include several habitat features (logs and snags) to increase its habitat function. As depicted on the attached Fieldbrook Commons Mitigation & Grading Plan (dated 9- 23-13), a split rail fence will be placed at the edge of the wetland buffer. There are no living spaces or recreational space next to the wetland or its buffer limiting use of this area. However, the City of Renton is requiring that the applicant provide a trail through the wetland buffer as depicted on the plan. We have moved this trail to the north, splitting the buffer area between the wetland creation area and Wetland B to the north to maximize distance of the trail from the wetland as best possible. Signage and a split rail fence along the trail indicates the character of the critical area and will discourage intrusion into the wetland or buffer. All lighting will be located outside the wetland and buffer. All lighting in the developed portion of the site will be directed away from the wetland and its associated buffer. Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. March 13, 2014 Page 12 The goal will be to create at least 25,430sf of area meeting all three wetland criteria (hydric soils, hydrophytic vegetation, and wetland hydrology) as specified in the Washington State Wetlands Identification Manual (W ADOE, March 1997) and the Western Mountains, Valleys and Coast region Supplement (Version 2.0) dated June 24, 20 I 0. All disturbed buffer areas will be restored with a dense planting of native trees and shrubs. The resulting wetland creation area will be monitored for IO years. The creation area will be delineated at Years 5 and IO to determine if 25 ,430sf of area meeting wetland criteria has been created. If there is not at least 25,430sfofwetland created, the shortage will be made up with either; I. Fixing any small grading or hydrology issue which may be impacting the overall size of the creation area, or; 2. Purchase of mitigation credits from the King County Fee program or other similar program at that time. Site Protection Instrument The entire mitigation site as well as the buffer and undisturbed wetlands will be placed within a Native Growth Protection Easement (NGPE) and recorded on title prior to occupancy of the project. Long Term Maintenance The mitigation area will be monitored and maintained over the IO year monitoring period. This will include trash removal, weed and invasive species removal, repair of fencing and signage. After the required IO years maintenance and monitoring period, the facility operating manual will include a description of the NGPE are and what type of maintenance can and should occur within this area. Management of the facility will be responsible for this work following the IO year monitoring and maintenance period. Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. PROPOSED MITIGATION 1.0 MITIGATION PROJECT OVERVIEW March 13, 2014 Page 13 To compensate for the fill of a 9,334sf Category Ill & IV wetlands, it is proposed to create 25,430sf of wetland between Wetlands A and C. Wetlands to be filled include Wetland D (7,671 sf Category II] wetland), Wetland E (68sf Category IV wetland) & Wetland F (l,595sf category II] wetland). 2.0 MITIGATION GOALS 2.1 Mitigation Goals The mitigation proposal is to connect Wetlands A and C with an area of25,430sf of wetland. The wetland creation areas will be densely planted with native vegetation. The use of diverse native plantings are expected to significantly improve the overall function of the wetland and buffer as it will remove dense thickets of exotic blackberry as well as add emergent and shrub plant communities into what is now, a single class forested wetland. 2. 2 Mitigation Goals 2.2.1 Create 25,430sf of emergent, scrub shrub and forested wetland. 3.0 CONSTRUCTION SEQUENCE The construction sequence of this project will be implemented as follows: 3. I Pre-construction meeting 3 .2 Construction staking 3.3 Construction fencing and erosion control 3.4 Clearing and grading 3.5 Stabilization of mitigation area 3.6 Plant material installation 3. 7 Construction inspection 3.8 Agency approval 3.9 IO year Monitoring inspection and reporting 3.10 Silt fence removal 3.11 Project completion 3.1 Pre-construction Meeting A pre-construction meeting will be held on-site prior to commencement of construction, to include the biologist, the City, and the contractor. The approved plans and specifications will be reviewed to ensure that all parties involved understand the intent of the construction documents, specifications, site environmental constraints, sequences, and inspection requirements. 3.2 Construction Staking Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. March I3, 2014 Page 14 The limits of clearing and grading near the critical areas will be marked in the field by a licensed professional land surveyor prior to commencement of construction activities. 3. 3 Construction Fencing & Erosion Control All erosion control measures adjacent to the critical areas, including silt fencing and orange construction fencing, will be installed. Erosion control fencing will remain around the mitigation area until clearing, grading and mulch placement are complete in upland areas outside the critical areas. 3.4 Clearing & Grading Clearing and grading in and near the existing sensitive area will be per the approved Final Mitigation Plans. 3.5 Stabilization of Mitigation Area All graded areas in the wetland or buffer will be stabilized with mulch upon completion of grading. Orange construction fencing and erosion control fences will be restored (if necessary) and placed around the critical areas. 3.6 Plant Material Installation All plant material will be planted by hand per detail and Construction and Planting Notes. The Mitigation Plan specifies the required size, species, quantity, and location of plant materials to be installed. The contractor will mulch areas disturbed during the planting process. Upon completion of the planting, the erosion control fencing will be restored and repaired. Plant substitutions or modifications to locations shall be approved in writing by the Owner's biologist prior to installation. 3. 7 Construction Inspection Upon completion of installation, the biologist will conduct an inspection to confirm proper implementation of the Mitigation Plan. Any corrections, substitutions or missing items will be identified in a "punch list" for the landscape contractor. Items of particular importance will be soils in pits, pit size, plant species, plant size, mulch around pits, and tree staking. Upon completion of planting, if installation or materials vary significantly from the Mitigation Plan, the contractor will submit a reproducible "as-built" drawing to the Owner. The As-built and installation sign-off report will be submitted to the Corps at that time. 3.8 Agency Approval Following acceptance of the installation by the City, the City biologist should prepare a letter granting approval of the installation. • 3.9 Monitoring Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. March 13,2014 Page 15 The site (wetland creation, buffer enhancement, buffer restoration and areas of temporary disturbance) will be monitored for IO years to insure the success of the mitigation project. If additional years of monitoring are required by the Corps, the plan will be revised to reflect this change. Any areas of temporary impacts that require restoration will be also monitored for the full 10 year monitoring period. 3.10 Silt Fence Removal Erosion control fencing adjacent to the mitigation area will remain in place for at least one year, and/or until all areas adjacent to the mitigation area have been stabilized. The City's Biologist may recommend that the fencing remain in place for a longer duration. 4.0 CONSTRUCTION AND PLANTING NOTES 4.1 Site Preparation & Grading 4.1.1 The Landscape Contractor will approve existing conditions of subgrade prior to initiation of any mitigation installation work. The Landscape Contractor will inform the Owner of any discrepancies between the approved construction document and existing conditions. 4.1.2 The General Contractor will flag the limits of clearing with orange construction fencing and will observe these limits during construction. No natural features or vegetation will be disturbed beyond the designated "limits of clearing". 4.1.3 The Landscape Contractor will hand grub all non-native invasive plant species including the removal of root crowns. These species may include, but are not limited to Himalayan blackberry, evergreen blackberry, English ivy, and English holly. Weed debris will be disposed of off-site. 4.1.4 The wetland area will be excavated to the depths shown on the Final Mitigation Grading Plan and brought to final grade with 8" of topsoil. The biologist will be on-site to confirm the grading is acceptable for planting. A total of 4" -6" of compost will be incorporated into the upper 12" of all graded areas in the wetland creation area. 4.2 Plant Materials 4.2.1 All plant materials will be as specified in the plant schedule. Only vigorous plants free of defects, diseases and infestation are acceptable for installation. 4.2.2 All plant materials will conform to the standards and size requirements of ANSI 260.1 "American Standard for Nursery Stock". All plant materials will be native to the northwest, and preferably the Puget Sound Region. Plant materials will be propagated • Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. March 13, 2014 Page 16 from native stock; no cultivars or horticultural varieties will be allowed. All plant materials wi II be grown from nursery stock unless otherwise approved. 4.2.3 No balled and burlapped, or bare root plantings will be used. Only container stock to be used. 4.2.4 All plant materials stored on-site longer than two (2) weeks will be organized in rows and maintained by the contractor at no additional cost to the owner. Plant materials temporarily stored will be subject to inspection and approval prior to installation. 4.2.5 Substitution requests must be submitted in writing to the Owner and approved by the Owner's biologist in writing prior to delivery to site. 4.2.6 All plant materials will be dug, packed, transported and handled with care to ensure protection from injury. All plant materials to be stored on site more than 24 hours will be heeled into topsoil or sawdust. Precautionary measures shall be taken to ensure plant materials do not dry out before planting. Wetland plants will be shaded and saturated until time of installation. Immediately after installation the mitigation planting area will be saturated to avoid capillary stress. 4.2.7 The contractor will verify all plant materials, the quantities shown on the planting plan, and the plant schedule. The quantity of plant materials shown on the plan takes precedent over the quantity on the plant list. 4.3 Plant Installation 4.3.1 All plant materials must be inspected prior to installation to verify conformance of the materials with the plant schedule including size, quality and quantity. Any plant or habitat materials deemed unsatisfactory will be rejected. 4.3.2 All plant materials delivered and accepted should be planted immediately as depicted on the mitigation plan. Plant materials not planted within 24 hours will be heeled-in. Plant materials stored under temporary conditions will be the sole responsibility of the contractor. Plants will be protected at all times to prevent the root ball from drying out before, during, or after planting. 4.3.3 All planting pits will be circular with vertical sides, and will be sized per detail on the mitigation plan and filled with pit soils approved by the Owner's biologist. Planting pits shall not be deeper than the root ball. If native soils are determined to be unacceptable by the Owner's biologist, pit soils will be amended with Cedar Grove mulch or equivalent. 4.3.4 No fertilizers will be used within the wetland. In buffer areas only, install "Agriform", or equal plant fertilizer to all planting pits as specified by manufacturer. Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. March 13,2014 Page 17 Fertilizers are allowed only below grade in the planting pits in the buffer areas. No sewage sludge fertilizer ("SteerCo" or "Growco") is allowed in the mitigation area. 4.3.5 All containerized plant materials will be removed from their containers carefully to prevent damage to the plant and its roots. Plants removed from their containers will be planted immediately. 4.3.6 All plant materials will be placed as shown on the approved mitigation plan. If the final installation varies from the approved mitigation plan, the contractor will provide a reproducible mylar as-built of the installed conditions. All plant material will be flagged by the contractor. 4.4 Planting Schedule and Warranty 4.4.1 A fall-winter installation schedule (October I st -March 15th) is preferred for lower mortality rates of new plantings. If plant installation occurs during the spring or summer (March 15th -Oct. I st) a temporary irrigation system will be required, unless the area can be sufficiently hand-watered. 4.4.2 All disturbed areas will be protected with an arborists mulch to a minimum depth of six inches. 4.4.3 The installer will warrant all plant materials to remain healthy and alive for a period of one year after final acceptance. The installer will replace all dead or unhealthy plant materials per the approved plans and specifications. 4.5 Site Conditions 4.5.1 The installer will coordinate with the Owner and the Owner's biologist for construction scheduling. 4.5.2 Landscape installation will begin after the City acceptance of grading and construction. The Owner will notify the Owner's biologist of acceptance of final grading. 4.5.3 Silt fences will be installed as shown on the approved mitigation grading plans. The installer is responsible for repair and replacement of silt fences disturbed during plant installation. No equipment or soils will be stored inside the silt fences. 4.5.4 After clearing and grading is complete in the mitigation area, exposed soils will be seeded or mulched. Orange construction fence will be placed around the mitigation area to prohibit equipment and personnel in the mitigation area. Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. March 13, 2014 Page 18 4.5.5 Final grading will be based upon soil conditions found during excavation of the mitigation area. 4.5.6 All plant material will be planted with suitable soils per planting details. Soils from planting holes will be spread and smoothed across the mitigation area. 5.0 MAINTENANCE PROGRAM This maintenance program outlines the program, procedures and goals for mitigation of the stream and buffer impacts at the mitigation site. This maintenance program will be the responsibility of the project owner through the duration of its ownership of the mitigation area, or throughout the duration of the monitoring period, whichever is longer. The maintenance contractor will complete the work as outlined below. 5.1 Maintenance Work Scope 5.1.1 To accomplish the mitigation goals, normal landscaping methods must be modified to include: a.No mowing or trimming of ground cover or vegetation in the mitigation area. b. No placement of fertilizers in the mitigation area. c. No placement of bark mulch or equivalent in the mitigation area, except as noted in the planting details. d. No placement of grass clippings, landscape debris, fill or ornamental plant materials in the mitigation area. 5.1.2 Work to be included in each site visit: a. Remove all litter including paper, plastic, bottles, construction debris, yard debris, etc. b. Remove all non-native and invasive species identified in Table 3-1 of Sheet W-3 of the Final Mitigation Plan within the mitigation area. All debris is to be removed from site and disposed in an approved landfill. c. Repair silt and/or permanent fencing and signage as needed. 5.1.3 Work to be completed on an annual basis includes: a. Areas containing non-native/invasive species identified in Table 3-1 of Sheet W-3 of the Final Mitigation Plan should be controlled by hand cutting and removing the root crowns for species such as Himalayan blackberry. Following hand removal, treating re-sprouting invasive/non-native species with a glyphosphate herbicide such as Roundup or Rodeo by a licensed applicator can be utilized. b. Replace dead or failed plant materials. Replacement plantings are to be of same species, size and location as original plantings. Plantings are to be installed during the dormant period. 5.2 Maintenance Schedule Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. March 13, 2014 Page 19 The Owner will conduct all items listed in the Maintenance Work Scope on an annual basis. Additional work may be required per the Monitoring Report and as approved by the Corps. Additional work may include removal of the grasses around each shrub and tree, installation of wood chips at each shrub and tree base and erosion control protection. 5.3 Watering Requirements 5.3.1 Watering with a temporary irrigation system will be required during the first spring and summer after the installation. The temporary irrigation system may be removed after the first year providing the plantings are established and acclimated to on- site conditions. 5.4 Close-out of Ten-Year Monitoring Program Upon completion of the monitoring program and acceptance of the wetland mitigation by the Corps, the maintenance of the project will be reduced to include removal of litter and debris, repair of perimeter fencing and sign age, removal of noxious weeds and undesirable vegetation, and repair of vandalized areas. 6.0 WETLAND AND BUFFER 10 YEAR MONITORING PROGRAM 6.1 Sampling Methodology The created wetlands and their associated enhanced and restored buffers as well as areas of temporary disturbance will be monitored once per year over a ten-year period, starting with the first year after the plants have been installed, and as required by the Corps. Monitoring will be conducted using the techniques and procedures described below to quantify the survival and relative health and growth of plant material. A monitoring report submitted following each monitoring visit will describe and quantify the status of the mitigation at that time. Vegetation monitoring will be conducted in August or September during monitoring years. Year 1 monitoring will occur at least one calendar year after installation sign-off. 6.1.1 Hydrology Wetland hydrology will be monitored using seven (7) piezometers per USACOE specifications. These will be located within the restoration area to be placed at the time of the installation sign-off by the biologist. Surface water level or ground water saturation depths will be measured at these stations to determine if wetland hydrology has been successfully attained. As is noted in the Corps of Engineers Wetlands Delineation Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. March 13, 2014 Page 20 Manual (Environmental Laboratory, 1987) and the Western Mountains, Valleys and Coast region Supplement (Version 2.0) dated June 24, 2010, wetland hydrology is defined as inundation or soil saturation ( usually within 12" of the surface) during the growing season. The growing season for this area is generally defined as the period between the middle of March and the middle of November. However, plant growth often occurs earlier in the year and sound professional judgment will be needed to determine when the growing season is taking place at the site. Hydrology will be monitored twice a month from March I st through May 30th of each year. Wetland hydrology will be considered successfully created if wetland hydrology is observed inundating or saturating the soil within 12 inches of the surface during the growing season 6.1.2 Vegetation The vegetation monitoring consists of inspection of the planted material in late summer or early fall (August-September) to determine the health and vigor of the installation, as well as coverage estimates. All the planted material in the wetland and buffer will be inspected during each monitoring visit to determine the level of survival of the installation. All plants will be inspected and recorded as to whether they are alive or dead based upon the "as-built" in Years I & 2. In Years 3-5, coverage estimates will be used to determine success of the vegetation component. A total of 27 permanent 3.0m rectangular monitoring plots will be located within the mitigation area as depicted on Sheet W-3 to monitor shrub and tree species coverages. Within each of these 3.0m plots, the emergent plant community coverage of vegetation will be measured with 0.25m rectangular plots. Estimates of coverage percentages will be made within these plots. Photographs of the mitigation area will be taken from 6 photo points to be located during the installation sign off as well as at each permanent monitoring plot. Photographs will be taken at each of the monitoring and included with the monitoring report for each year from these points. During years l & 2 of the monitoring, replacement plants as well as dead plants will be flagged with distinctive flagging to distinguish what plants these are. Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. March 13, 2014 Page 21 6.2 STANDARDS OF SUCCESS TABLE 3-1: PERFORMANCE STANDARDS 1T!M ftAIIS TO K MONITOMD ........._,.,,,..,... WITlANO HYDROlOGV Y£AltS 1, 2, 3, 4, 5, 7 ANO 10 SOll5 WITHIN CJIEATW wtll.AND AREAS SHAll IE SATUAATCO TO TH( SUflfACt, HAvt SHAJ..LOW jCfl;E,1,ltO WlTLANO ANO GflOUNOWATEII mstNT WITHIN 12 INCHn OF THE SOIL SUJIFACE, M!!?L2.'! HAVE SLl'IFACE PONDING WUIAND A/WliTLAND C} PRU£NT FOR AT I.WT FOUR 14) CO"JS,£CUT1Vl MUS DUIIIN<i TH( GM)WING SEASON WHEN RAINF.W.IS L!SS THAN OR. EQUAl TO THE MEAN FOR THe PEIUOO Of AVl'Jt.Allf RECORD. wrnANO DELINEATION 't£ARS 5 AND 10 PE .. FORM DEUNEAnoN OF WETLAND A, WHI.ANO C, ANO WETLAND CREATION JINA TOOHElMINE IF WHtTHEk WHtAND A A~WHLANO C Ml o\FffCTEO BY H4E WU\ANO c«EATION. n:~ .. MANCE STAHDAAO ISSA.TISAEO IF TltEIU IS NO CHANGE TO WfllAJ\10 tlMITS. AATMVEGETATION YEARS 1, 2, J, 4, 5, 1 AND 10 TREE AND SHRUB SPECIES (<:«EA.TEO WETlNID/ {TO OCCUR IN AUGUST Oft . ioo,i.5Ullvlv4 jy iNSTAUEO PLANT STOO: Amil THE FIii.ST GROWiNG SEASON . ENHANCED WEfl..ANO 8UFFEIIJ Sff'ltt.4SER KGIN..iNG ON[ . eo,(. S~\/Al BY INST.Jill ED PLANT 5100: AFTER Ttlf SECOND GIi.OWiNG SEAS<»! . VEAR FOLLOWING INITIAL . INHANaD IIUffU f'lANTING AUAS: MINIMUlll rfllCfNT 00V£R IY TRffSANO Sl'IRUIIS:-Vf.U J: ,LANT INSTALlATl'.>N.) ~; Y£AR S: •'516: ViAll 7: &5%; Vl.U IO:'°"· UP TO 20%0f TttE HAT!VE 'WOOOY l't.ANTSJ'fCIES COVERAGE MA't' 9£ COMPRISED Of Df$HtA&1.E NATM (OlONIZING SP£0£S. . AFTER THE FIFTH GROWING SEASON, A MlMMLIM Qi: FOUR. OIFFElENT l'tANT SPEOES Will COMPR!St: GflEATU THAN 1<1% COVERAGE. . atlAllD WfT\AND NANTINI MEAS: M!HIMUM ,ERCENT COYER l't' ill ES ANO SHRU!S: YEAJI; 3: ~; 'tfAA S: ~; YUR 7: ~; 't'UR 10: 90%. U,TO ~OF THE NATIVE 'WOOO't' Pl.AHTSPECIES covalAGE MAY Ill COMl'1'1$EO Of OEstll.AllE MATIVE COlONIZINGSPEOES.. . AFTI:ll THE FffTft GftOWtt.lG SEASON, A MINIMUM OF FOUR DIFFERENT ,l.ANT SPEms WILL COMPRl$f. GREATER fHAN 10% COYEAAGE. EMERGENT SPECfES . :!Si Avtildt COVERAGE l't' INST4llEO PL4NT STOO: AFTER THE Flf\ST GROWING S£ASON . . 8°"AVEAAGE COVERAGE IY IHSTAWO PLANT STOO:AFTER THI 5TH ANO 7TH GROWING SEASON . . ~AVERA6E COVERAGE IY NATM EMERGENT ,I.ANT ioPEOES AFTER THE UNTH GROWING SIMON • . AFTER TliE FIFTH GROWING SEASON, A MINtMUM OF Ttll{ff OlffERENT PLANT S,E<:1£5 Will COMPfUSE GQA.Tlll. THAN 1°"" COVl:AAGE. NAT!Vi W.GHATION vtAAS 1, 1, 3, 4, S, 7 AND 10 . 100% SUR'/lVAL IY INSTAJ.110 PLANT STOO:AflER THE FlllSf GROWING YASON . {RESTORED WE HANO 9Uff£R (TOOCCUR-..AUGUSTOR . BOK SURVIVAL IV INSTAillO PLANT STOCK AFTER THE HIRD Gl\owtNG S£ASON . ANO Al\[ASOfTEMPOMRY HPTIMM.I\ IEGINHlNGONE . MINIMUM l'fRCENT COi/ER IY TREES .ANO SIUIU6S: VEAR 3: 30%; 't'EAlt 5: 45-%; 't'EAR 7: 6S'lli; ~ 10: D1STUfl5ANC!} YEAR fOllOWIHG 1NlTlAl IO'K. u, TO 2°" OFTHf NATM: WOOOV l'lANT S,fOfS COVIRAG£ MAV If COMPIUSfD or PlANT INSTAI.LATION.) DESIAA!LE NATh'E COt.ONtZJNG SPEQl;S. . i\FltR THE FIFTH GROWING SlASON, A MINIMIM OF FOUR DIFFERENT PLANT SPEOES Will COMPAISf: GRtATIR THAN 10'6 COVERAGE. NOXIOUS WEED SPECIES YEARS J, 2, 3, ,, S, 7, ANO 10 USS THAN l°"COVfllAGE IVAI.LCWS "A", "l",AHD"C" NOXIOUSWE£DS(l~UDINGNON-REGUI.ATt0 "II" ANO "C" NOXIOUS WHOSt 10£NTIFl(0 ON THf lATIST KING COUNTY NOXIOUS Wt:!O UST. NOXIOUS WEED CONTROL ~MORMANC£ STANDARDSMtf LMTED TO PI.AN'l'ED NlfAS ONLY. 7.0 CONTINGENCY PLAN 7.1 A contingency plan can be implemented if necessary. Contingency plans can include re-grading, additional plant installation, erosion control, modifications to hydrology, and plant substitutions including type, size, and location. 7 .2 Careful attention to maintenance is essential in ensuring that problems do not arise. Should any of the site fail to meet the success criteria, a contingency plan will be developed and implemented with the City approval. Such plans are prepared on a case- by-case basis to reflect the failed mitigation characteristics. " " Fieldbrook/#11-121 Sewall Wetland Consulting, lnc. March 13, 2014 Page 22 7.3 Contingency/maintenance activities will include, but are not limited to: -Replacing all plants lost to vandalism, drought, or disease, as necessary. -Replacing any plant species with a 20 percent or greater mortality rate with the same species or similar species approved by the City Biologist. -Irrigating the mitigation area only as necessary during dry weather if plants appear to be too dry, with a minimal quantity of water. -Reseeding wetland and buffer areas with an approved grass mixture as necessary if erosion/sedimentation occurs. -Removing all trash or undesirable debris from the wetland and buffer areas as necessary. If you have any questions regarding this report, please call us at (253) 859-0515 or at esewall@sewallwc.com . Sincerely, Sewall Wetland Consulting, Inc. Ed Sewall Senior Wetlands Ecologist PWS #212 Vanessa Dolbee From: Sent: Kathleen Reader <kathleen@bradtree.com> Tuesday, March 11, 2014 1 :34 PM To: Vanessa Dolbee; Justin Lagers Subject: Fieldbrook -interior parking-shrub calculation Hi Vanessa, Thank you for your call today. I went into the CAD drawing for Fieldbrook and extracted the calculations as requested. They are as follows: 1590sf of interior parking landscape area is required 1 shrub per 20sf of landscape area= 79.5 shrubs (no more then 50% deciduous) Quantities provided on plan: Evergreen Shrubs: 290 Deciduous Shrubs: 61 The landscape plan and drawn meets the intent of this code section. Please let me know if there is anything you need to complete your approval of this project. Kind regards, Kathleen Kathleen Bradley Reader RLA, ASlA Principal BDG Bradley Design Group, Inc. Landscape Architecture+ Site Planning o. 253.272.4848 ,. 253.27&.0 132 www.bradtree.com 1 May 6, 2013 Revised February 26, 2014 ES-2089.02 Earth Solutions NW LLC Avana Trails, LLC c/o American Classic Homes 9725 Southeast 36th Street, Suite 214 Mercer Island, Washington 98040 Attention: Mr. Justin Lagers Subject: Revised Coal Mine Hazard Traffic Loading Assessment Proposed Fieldbrook Residential Plat Southeast 172nd Street Renton, Washington LUA13-001109 FPUD Reference: Final Planned Urban Development Report & Decision Dated February 21, 2014 Earth Solutions NW, LLC Plan Review Letter ES-2089.02, dated May 6, 2014 Earth Solutions NW, LLC Geotechnical Engineering Study ES-2089, dated December 13, 2011 Dear Mr. Lagers: • Gcotechnical Engineering • Construction Monitoring ' Environmental Sciences City of Renton Plannir iq Division In accordance with your request, Earth Solutions NW, LLC (ESNW) has prepared this revised letter providing additional pavement loading and recommendations for the subject project as it relates to the existing coal mine hazard and buffer area. We understand as part of the referenced final conditional approval (item #18), further analysis that pavement designs near the proposed trash collection area can withstand heavy traffic loading from commercial and emergency vehicles. We understand the trash enclosure area has been relocated out of the Coal Mine Hazard buffer area. 1805 -136th Place N.E., Suite 201 • Bellevue, WA 98005 • (425) 449-4704 • FAX (4251449-4711 Avana Trails, LLC c/o American Classic Homes May 6, 2013 Revised February 26, 2014 ES-2089.02 Page 2 In our opinion, the following pavement section recommendations will provide adequate support for occasional HS-20 traffic loading associated with trash collection and loading from commercial/emergency vehicles including, but not limited to, parking of fully-loaded emergency vehicles. The design recommendations were evaluated using a maximum gross vehicle weight of 50,000 pounds and outrigger pressure of 75 pounds per square inch (psi) for emergency vehicles. This section is also provided in the referenced geotechnical engineering study which requires the subgrade be proof-rolled using a loaded dump truck, which would mimic the weight imposed by loaded trash and emergency vehicle loads. In our opinion, the occasional heavy traffic loading and parking is considered transient and is not likely to cause subsidence within the existing coal mine hazard area. "The proposed parking/trash facility would be an appropriate use located within the hazard area". Heavy Pavements The performance of site pavements is largely related to the condition of the underlying subgrade. To provide adequate pavement performance, the subgrade should be in a firm and unyielding condition when subjected to proofrolling with a loaded three-axle (100,000 pound gross vehicle weight) dump truck. Structural fill in pavement areas should be compacted as recommended in the "Site Preparation and Earthwork" section of the referenced geotechnical engineering study. It is possible that soft, wet, or otherwise unsuitable subgrade areas may still exist after base grading activities. Areas of unsuitable or yielding subgrade conditions will require remedial measures such as overexcavation, placement of a geotextile and thicker crushed rock or structural fill sections prior to pavement. For relatively high volume, heavily loaded pavements subjected to moderate to high, loaded truck traffic, the following preliminary pavement sections can be considered: • Three inches of hot-mix asphalt (HMA) placed over six inches of crushed rock base (CRB), or; • Three inches of HMA placed over four and one half inches of asphalt treated base (ATB). The HMA, ATB and CRB materials should conform to WSDOT specifications. All soil base material should be compacted to at least 95 percent of the maximum dry density. Avana Trails, LLC c/o American Classic Homes May 6, 2013 Revised February 26, 2014 ES-2089.02 Page 3 We trust this letter meets your current needs. If you have any questions, or if additional information is required, please call. Sincerely, EARTH SOLUTIONS NW, LLC Kyle R. Campbell, P.E. Principal Earth Solutions WI, LLC February 26 1 \ 2014 Vanessa Dolbee Senior Planner City of Renton 1055 South Grady Way Renton, WA 98057 RE: Fieldbrook Commons Final PUD, LUA13-0011009, FPUD Mrs. Dolbee, Please find enclosed the following (re)submittal items as required in your Administrative Final PUD report & Decision dated February 21, 2014: • 2 copies of the updated Site Plan • 3 copies of the Landscape Plan • 3 Copies of the Tree Retention Plan • 3 Copies of the Irrigation Plan • 3 Copies of the Final Wetland Mitigation Plan • 3 Copies of the Final Wetland Mitigation Report • 2 Copies of the proposed Wetland and Coal Mine Kiosk • 2 Copies of the Geotech letter Please let me know if you require any additional information. m Lagers Director of Land Acquisition & Development Avana Trails, LLC Business Office 9675 SE 36" Street, Suite 105 Mercer ls/and, WA 98040 P: (206) 588-1147 F: (206) 588-0954 Tree Retention Legend NOTE: CRITIAL N>.EA TREES ElC"1'llfOCR!TICAI.ARU.Til!!E:STOl>:EMAJN {P OE.o.D.-•o.""""'OA:tw,t()EAC)IJSTI>E.SLOCI.TW INCRmcAll'PU.S nt!'ES IN EXl5"'1~G CRfflc.t,LAAE,1,S TO BO REMO'VEDOR NT!i:"1W.l.Y EFFE<:lE<l RV .... n..oJ<p CR .. TIOHACrnmY f'-.... --"'-"'"') DEVELOPABLE AREA TREES PSAI), D .. EASH>. D'l'1NP OIi °""""ROUS TIIEE9 -TO BE "'- EXISTING VLW.E'n'llce.!ITOBE~[hl<Mll.c.OC,o,n,pQN Del'ELO<>,..LS PORT1C« OF Sil EJClllTI>,t: VLW.ETMES,N~OWTOOE~[hl<Mll -LOCA1'0<> DEVELOP,.,.LS "°"1iOHOF SITF EJ(l5TIN<l "1"8lC Tl<EE$ TO !1£ ...... l~A'1EI, COO<OTI<UCITON 2061 -TRtt •lf«R POINTS-· "'2J.~ --Till'l,El.EVATIO'I 20.l~M -TREECAl.rPE~&-°"'a =es . .,...._ __ =·--·-·-uca.US'TVl·-Tlllnl<--- TREES LOCATED IN THE THREE WETLAHDS TO BE FILLED ( 'D', 'E' AND F') W£RE NOT CALCULATED AS "CRITTCAL AREA9" TREES. TREES WERE CALCULATED AS VIABLE OR DEAD, DISEASED, DYING OR DANGEROUS -SEE PLAN FOR TREE DESIGNATIONS. Tree Retention Calculations 1 Tot,,I Nu-of r.-•nd Condition -,,. on Pn,Jacl 1111:a --119po,t (GrM-Inc, -S.pt. 8. 2011) • 7MTotal T,_ 2a. 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SCHEDULES, NOTES & DETAILS! ~- 111~ j Fieldbrook Commons Preliminary PUD i ! >-' '-_ Fleldbrook Commons. LLC i' 17100 lllock of lo.'lth Av.:nut SE, Ra,ton, Kin,; County. WA ' ,1. ,1, 1, I• , I, " k' ; ,. . ' ' ; ;jl;; ;;! ;; I:.!;; ; I;; I s ' s -' i l:l 1:111: nin j i j ' ' ' -I f I! I I I ""C II) ;. -· :1!-... ' ' I ' I ;!;f;,J . "' "' ::;.: CD ""C -DI :::, ;11-... . . l ; I I I ( I I \ \ "-- Overall Site Plan Fieldbrook Commons Preliminary PUD fle\dbrook Commo1u, UC 17100 Bloc! of 108th Av-enue SE, Renton, King County. WA .... I ·1 ·11 " .;, " ,, a -' " -., ~ I :'1 ,, ""' 'iim !' ' 1' :1! -'"'. I ' ---~:!i' ' ~ ~ , LANDSCAPE PLAN -WEST Fieldbrook Commons Preliminary PUD Fleldbrook Commons, LLC 17100 Block of 1ogth AYenue Sl. Renton. King Coun\)'. WA I 1 -------4--;--- !! •! I I I ' I :1, ' , l ' -·· ' LANDSCAPE PLAN -MID. Fleldbrook Commons Preliminary PUD Fieldbrook Commons. 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PNW HOLDINGS LLC -FIELDBROOK COMMONS CITY OF RENTON Sewall Wetland Consuhing, Inc. 27641 Covington Way SE, #2 Covington, WA 98042 MITIGATION PLAN 2-24-2014 NWS-2012-1281 Prepared For: PNW Holdings, LLC 9675 SE 36 1h Street Snite 105 Mercer Island, Washington 98040 Attn: Justin Lagers February 24, 2014 Job#ll-21 City of Renton PJannin~:-1 Division FEB 2 6 10i4 Phone: 253-859-0515 Fax: 253-852-4732 Sewall Wetland Consulting, Inc. 27611 Covingtm Way SE #2 Covington WA sro!2 PNW HOLDINGS LLC -FIELD BROOK COMMONS CITY OF RENTON 1.0 INTRODUCTION MITIGATION PLAN 2-24-2014 NWS-2012-1281 Phare: :filS59.IB15 Fax: 253-S52-4732 This report describes the proposed wetland mitigation for the Fieldbrook Commons PUD project, located on the east side of Benson Road South, and north of Cedar A venue South (SE l 72"d Street) in the City of Renton, Washington (the "site"). 2.0 PROPOSED PROJECT & MITIGATION SEQUENCING The purpose of the proposed project is to construct a multi-family apartment complex as the property has been zoned for, as well as planned for in the City of Renton Comprehensive plan. The need for apartment units within Renton is high and this project has been proposed to meet that need. The proposed project is the construction of a 161 PUD project with associated infrastructure. The location of Wetlands D, E and F result in most of the developable property on the site being encumbered by wetland or buffer. Since these wetlands, particularly Wetlands E and Fare of low value, and Wetland Dis small in size but because of its linear shape impacts the sites usable space so greatly, we are proposing filling these three wetlands. As a result, it is our intention to fill these wetlands and provide adequate mitigation for their lost functions by creating wetland on the eastern side of the site in and around Wetlands A, Band C. Impacts to wetlands must be justified through a mitigation sequence as detailed in City of Renton Code. Ideally we would be able to use the King County fee mitigation banking process as is preferred by the Corps and W ADOE. We are in agreement that using the fee-in-lieu mitigation option would be ideal and the easiest/fastest way to mitigate the proposed impacts. However, the City of Renton has refused to let us use this as a mitigation option as it moves the mitigation area outside the City limits and in their opinion is a net loss of critical areas to the City. It appears the City looks at the mitigation, and ttail through the buffer as part of the "public benefit" aspect of this project. The construction of the mitigation onsite, as well as the placement of a trail through the buffer are being required by the City to allow us to construct this Fieldbrookl# 11-121 SewalJ Wetland Consulting, Inc, February 24, 2014 Page 2 project. It is our opinion that the trail does increase the amount of human intrusion into the wetland, and would be best left off the plan. However, the City of Renton will not accept this and are forcing us to bring a trail through the buffer regardless of the logic. The next best option is on-site replacement of the wetland area and functions as proposed in our mitigation plan. The attached mitigation plan has been prepared with the recommended documents elements as requested by Suzanne Anderson of the US Army Corps of Engineers in previous comments. This plan is prepared in the exact same manner and with the same information as numerous mitigation plans we have submitted and had approved by the Corps for various Nationwide as well as Individual Permits. As requested the monitoring has been modified to include I Oyears of monitoring. (c) Per the Federal Mitigation Rule, you must provide additional information to document that a watershed approach to compensatory mitigation was used for the mitigation plan (33 CFR 332.3(c)]. A link to Wetland Mitigation Situ Using a Watershed Approach, F.cology Publication #09-06-032 is available fiom our webpage at www.nws.usace.anny.mil, select "Reau)atory Branch, Permit Information", then "Mitigation Resources", then "Mitigation Tools". We ffl:ODllDelld that you demonstrate that the chosen mitigation site satisfies criteria in Charts 2 and 3 of the site selection guidance (i.e., identified as a site with potential and that is IIUIBimble); and that it satisfies criteria in Charts ,4 throup 11 for the appropriate functions. Using Chart 2 from the Watershed approach which is an analysis utilized to pick a mitigation site is not really applicable, as the City of Renton is requiring we conduct the mitigation on the site where the impact is occurring. In addition, there is no other available mitigation sites within this drainage basin that is owned by either the City or the client for use as a mitigation receiving site. Therefore, mitigating on-site is the only feasible alternative given these constraints. In regards to Chart 3; Question 3A: Identify the watershed processes that have been altered within the hydrologic unit where the mitigation site is located. Human activities can change watershed processes by changing water flows; introducing nutrients, pollutants, non-native species. and sediment; and by fragmenting habitats. Changes in these processes often create problems that can be improved through mitigation activities. To begin you need to identify the major landscape-scale problems (i.e., alterations to processes, not structure) that exist in the hydrologic unit where your site is found This will help you identify which restoration or enhancement actions will be the most effective in that hydrologic unit. Check the appropriate column in the following table to identify problems that might exist. The last column notes if the altered process has already been identified in an existing watershed plan as a problem that needs to be addressed Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 3 The current flooding events within the Soos Creek drainage are generally not increasing due to the current use of modem storm water facilities within the basin. However, there still is some increase as there is more water getting to the basin faster in storm events. There is less eutrophication in rivers and streams in the basin primarily from removals of livestock and old septic systems. Water quality has been reduced in the basin to a degree. Some stream and bank erosion does occur within the basin. Habitat has become more fragmented as the area's population grows and more development occurs. Question 3B: Will the mitigation result in a wetland of the appropriate hydrogeomorphic (HGM) class for the landscape setting? Wetland mitigation sites are sustainable only if the type of wetland being proposed is appropriate for its position in the landscape. The HGM classification of wetlands is based on characteristics of water movement and position in a landscape. Therefore, it can be used to identify appropriate wetland types for different locations in a hydrologic unit. Yes, we will be mitigating for depressional wetlands with a depressional wetland mitigation area. Question 3C: Will the primary source of water to the mitigation site be appropriate for the HGMclass? Groundwater and direct precipitation will be the source of hydrology for the wetland mitigation site as was the source for the impacted wetlands. Hydrologic monitoring of the mitigation site has shown that surficial groundwater elevations in the mitigation area will sufficiently hydrate the creation area with soils saturated to the surface and some standing water in the growing season. Question 3D: Will the site have an adequate supply of water to maintain a wetland without engineering the delivery of water that would require long term control or maintenance? The surficial groundwater monitoring and proposed grades should create a wetland area that will require no additional or artificial source of water to maintain its viability. It is thought that Wetland A which is located within the area of an old mine is discharging water from historic mining and as such there is an abundant supply of water in this area. Question 3E: Will the mitigation activities maintain hydric soils, if they exist, at the site? Removing hydric soils can decrease the potential for success of wetland restoration. Hydric soils often contain a seedbank of wetland plants that supplement any planting you may propose. Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 4 Hydric soils from the filled wetlands will be mixed with topsoil and utilized in the newly created wetland maintaining viable seedbanks. Question 3F: Can the mitigation be designed to control aggressive plant species? There is currently not a predominance of aggressive invasive or weedy species in the area of the proposed mitigation or the two wetlands that will be connected together with the creation. Standard invasive species control will be utilized in the mitigation area which has proven successful in other mitigation sites. Regarding the appropriate Charts 4-11; Chnl't 5-: Goal~ Impro,iug Hydrology Functions in Depressional Systems Outside of floodplains ...... ~ ... 81]01lii • •• ' ....,_ .. KIIICNllll'elnu MaylN, PN*tto..,,..,. ~ fiactimf, IU'I' plM ~,_,_ ... ~ . ............ willlill! -(FteMllt......,, .. 4ilcNI .... 11w1 ettbe IUlfNI. M 1191 lle\lll dlpNiniol\f Man"-'!"Wftll'. (lotoJ'lffl..-J Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 5 Chart i: Gval -Imprm:ing \Yater Quality (WQ) Funrtiom in Depres5ion;,l S.y~te1m Outa;ide of floodplain<.. can .. 11111n1.._ildll.. 1- wellMdNu .-.Mad? .. ... .. Chari 10: Goal -lmpro,ing Specie-~ Rkhne,s of\Hldl:lft> ·>'_JJJ_·_-· tk)jW . c..., ..... 111111111 :=::=::a.:-... • --· · .. ·l'O·.· ····.··.¥!;, • . . i.llll'IMI . . ·. •••f0 l'l!il:Wt .. ~i • • . . IIICrNN .. ~ .. toil in ,tffiO¥i11C poia'IMt"' IHinC --liwttoMll...-;.nJ =-"= --.............. ld4' .. - ........ ..._, ca • ...., ....... ............ • • .. -.. - ... __ _ .... 1,•c ::c;--.• €> ... .. ... • • .. -~~~':, c·h,,rl ll: Goal, ltn}ll"O\ing Spedt'5 Richn1><;~ of Plant<; ~j-"""'''* '·''·"~--··· ·-- •.•• --~ ~_,.~ CM .. ~...-..... TN ~·-.......... CNINl!lid? . -= This sequencing requires addressing the following criteria; a. Avoid any disturbances to the wetland or buffer; Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 6 -:~a::=;,::-.= sih -,., kl't ... .,.. dtKl'ibt "°"" ~--~"'" .... _ (lotoMd ..... J ~~~Ull ......... 111"" ,,...,.,1"'11t111N~11t-...... lMNil .,.,.,....;"l...,. ............... a....-y,...,.,. 11 lun I )'ftl'II ,,.., • «ftl1' Hlivilil,i;. ____ .,_...., C.......iftl..,.... ..... wil...cl• O'ICl ..... -~.,lilelia ........ -.-.-~-....... -..~ ....,.,._ 0-. ......... ~ ,..._;... ,...;. st...,lill lM-.11 ... 11, ,i.ntirc .. .._.~.,._.rl\Ma~-..-.-.11111 ...,_.,. ._.;u_ _..,... ....... I ..... _ _,....._,..__..,. .... ~ 1,-tudaa"VMiol IJI& U.. I ......... -.ti> t lllp s,Mitl ""- .W ~ ii -........ plll. l,.io,e -*ial......u ... .., ... -i,,~ ==::.~::"...: - The site contains three small wetlands which the developer proposes to fill and mitigate for through the creation of a new wetland area and enhanced buffer areas for the existing and remaining wetlands A, B & C in the eastern third of the site. Wetland F located on the western side of the site is Category III wetland measuring I 595sf. Due to the requirement to provide a secondary fire access directly out to I 08'h Ave S.E. the developer is unable to avoid direct impact to this wetland. Wetland E, located in the center of the site and adjacent to S.E. 172nd St. measures 68sf and is rated as a Category IV wetland. Due to the requirement to dedicate and construct the other half of the S.E. 172nd St. ROW the developer is unable to avoid direct impacts to this wetland. Wetland D is located generally in the center of the project and is rated as a Category III wetland measuring 767lsf. b. Minimize any wetland or buffer impacts; The developer previously attempted to plan roadways and improvements around Wetland D, however the location and shape of the wetland impacted the vehicular circulation and Fieldbrook/# I I -I 2 I Sewall Wetland Consulting, Inc. February 24, 20 I 4 Page 7 building locations to such an extent that the project would not be financially feasible to construct. c. Restore any wetlands or buffer impacted or lost temporarily; and Restoration of Wetland Din this location would not be feasible due to the location of the impacts and configuartion of the parcel and remaining wetland. d. Compensate for any permanent wetland or buffer impacts by one of the following methods: i. Restoring a former wetland and provide buffers at a site once exhibiting wetland characteristics to compensate for wetlands lost; This is not applicable to this site as no historic wetlands are located on the property. ii. Creating new wetlands and buffers for those lost; and A total of9,334sfofwetland will be filled. US Army Corps of Engineers Required Mitigation Using the recommended ratios from Table 1 a, of the W ADOE Publication Wetland Mitigation in Washington Stale Part I, (WADOE March 2006 Pub. #06-06-01 Ja) Table 1 Wetland Size Category Vegetation Ratio Required Type Wetland Creation D 7671sf III Forested 2:1 15342sf E 68sf IV scrub-shrub 1.5:1 102sf F 1595sf III scrub-shrub 2:1 3190sf Total 9,334sf 18,634sf As described above, based upon the required USA COE and W ADOE ratio, a total of J 8,634sf of wetland is required to be created. • Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 8 The proposed mitigation will create 25,430sf of wetland, which exceeds the required USACOE ratios by 6,796sf. The extra wetland being created over the WADOE recommended ratios is a result of the City of Renton having a higher mitigation ratio requirement than the Corps. As seen in Table 2 below, using the three main functions from the W ADOE Rating System recognized by the Corps, a substantial functional lift will be attained from the connection of Wetlands A and C with 25,430sf of additional wetland over the existing functions of the proposed fill wetlands. Table 2. Functional Comoarison of imoact wetlands and orooosed miti ation Wetland Area Flood Species Water Hydrologic Habitat Storage Richness Qual. Function Function caoacitv Function Category WetlandD 767lsf 3800cuft 5 snecies l2vts 8vts 13vts III Wetland£ 68sf 34cufi 2 snecies llvts 4vts IOvts IV Wetland F l595sf 500cufi 5 svecies 20vts 8vts llvts III Pronosed 25430sf 7600cuft 15 soecies 24ots 20ots 2Iots II Functional +16096sf +3266cuft +Sspecies* +9pts +12pts avg +9pts +l I Lir, av11: av11: Cate11:orv *only 7 different species were found (excluding exotic/invasives) in Wetlands D, E &F The newly created wetland will connect to existing Category III wetlands (Wetlands A and C) and provide enough lift that this wetland will now be considered a Category II wetland under the WADOE rating system. This is a substantial lift in function, surface water storage and species richness over the fill of Wetlands D, E & F, which are generally low value Category III and JV wetlands. Hvdrologic monitoring of mitigation sile and general construction overview To compensate for the impact to 9,334sf of Category III & IV wetland, we will create 25,430sfofwetland between Wetlands A and C. This results in an overall wetland mitigation ratio of 2.72:1 (created wetland:impacted wetland). This mitigation will create Category II wetland for a combination of Category Ill and IV wetland impacts. As depicted on the attached Final Mitigation Plan, 25,430sf of area will be excavated out to a similar depth to the existing wetland in two areas to intercept the surficial groundwater table and create conditions favorable to create wetland hydrology. A series of 6 monitoring pits/wells were located within the proposed wetland mitigation area. These were monitored with weekly site visits from April of 2012-August 2012 as well as March and early April of 2013. At each of these points soil saturation and water table levels were measured to determine what surficial groundwater elevations are, to facilitate designing grades for the new wetland creation area. What we found was that within the proposed creation area, groundwater levels in the early growing season area Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 9 between 14" -30" below the existing surface (see table below). It is assumed in the very early growing season (February and March) the groundwater elevations are shallower than the measurements we took, meaning the groundwater elevations are closer to the soil surface. As shown on the attached Final Mitigation Plan Sheets W l-W3, we utilized these existing groundwater contours to create the new grades for our mitigation site. As can be seen by the grades and associated cross-sections, the grades will remove soil down to the existing groundwater elevations to create wetland areas with soils saturated to the surface for the early growing seasons, to also include flat areas that will hold some shallow I" -3" of surface water to provide a variety of wetland hydro logic regimes from saturated, to seasonally flooded. The fact that the excavation is being brought to the higher levels of groundwater within the growing season, and will not cut into the surficial groundwater table, should alleviate the concern of intercepting and draining off this water. All we are doing is removing the surface soil above the existing sloping groundwater table to make those saturated soils closer to the surface. Soil disturbance of the groundwater retaining portion of the soil column will not occur. Although creation of a slope type wetland is not the most conventional or common mitigation method, it is a feasible method of wetland creation when conditions warrant its use. Our company has been involved in two larger wetland creations using this type of concept, most recently a 3 acre wetland creation with over IO' of vertical drop across the landscape in sloping of the creation area (see Snohomish County Parks Centennial Trail II mitigation plan reviewed and approved by Jonathan Smith of the Corps). By using the same method of removing soil down to the level of the highest groundwater elevations as is proposed in the Fieldbrook project, we successfully created a 3 acre sloping wetland in the previously described project. Table 3. Groundwater elevations below surface o hvdrolo• v monitorin21JOints 2012 Monitor DATE point& elev. 4113 4127 5111 5124 617 6128 7112 A417.5' -15 -14 -15 -20 -26 drv drv B418' -17 -16 -16 -22 -27 dry dry C417' -20 -18 -17 -20 -25 dry drv D416.5' -14 -14 -14 -16 -20 drv dry E4 l 8.5' -27 -26 -24 -30 -36 drv drv F418' -21 -22 -20 -28 -36 drv drv Note: All elevations indicate the elevation of the saturated capillary fringe of soil saturation observed in hydrology monitoring points. 8112 drv drv drv dry drv drv Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 10 Table 4. Groundwater elevations below surface o 'hvdrolo1 v monitorinl! points 2013 Monitor DATE point& elev. 3/15 3/29 4/9 A417.5' -12 -I 0 -15 B418' -15 -15 -14 C417' -17 -16 -18 D416.5' -IO -11 -13 E418.5' -23 -20 -23 F418' -18 -19 -20 Note: All elevations indicate the elevation of the saturated capillary fringe of soil saturation observed in hydrology monitoring points. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . { ... ,, ........ . . . . . . . /' •' .... . . . : : : : : : : : : :;.:: :~,:::::::::: .·.·.·.·.·.·.,~.·.·/.'.·.·.· ... • • . . • . . . • . • • • r •..•. ·., ...•.••••.. . ·.·.·.·.·.\';•, ·.·.·;. ·. ·.·.·.·.· I ,,. ........... . ...... . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. l:riJting1u,fo.u 418 ;..,.A~~~~w,;....--~~\+--~~~~.J;w,__~~--=;c iiil--1 ~~~~~--+-~--l---'~\~~~~~ ..... ~ll----~~--11 413~. ~~~~~~---',,,:h,;,:"""'4c;,.c;;:_;Zw;:.::.,f'..:ab:;:_~~~~~~L. ~~~~--'- Emting 1ur(aa B 419A~~~------"W'-------~~~"----"--~~~~~~~~-----=: l~I'-~~------E~,,.,,,,,,,,d,,..,""""'.,it..,__~"~~~~~~~/~___JI 41 41 41 41 41 41 41 411 8A 7 6 5 4 . ' w / Pr-----" iuw-adt \ -' I '\ ,, ' ' '\ February 24, 2014 Page 11 ~~ •Af1>1oxm'.111.W poundwatft elevation D '\ '\ ' '\ --. A small berm will be placed between the wetland creation area and Wetland B. This will prevent (in the unlikely case of surface water overtopping the edge of the wetland) the wetland creation area between Wetlands A and C from draining into Wetland B. Hydrologic monitoring will be conducted using peizometers in the proposed mitigation area through the winter and spring to verify groundwater elevations. This area will then be graded back at a slope no steeper than 3: I (horizontal :vertical). The area will then be planted with a mix of native trees, shrubs and herbaceous species and will also include several habitat features (logs and snags) to increase its habitat function. As depicted on the attached Fieldbrook Commons Mitigation & Grading Plan ( dated 9- 23-13), a split rail fence will be placed at the edge of the wetland buffer. There are no living spaces or recreational space next to the wetland or its buffer limiting use of this area. However, the City of Renton is requiring that the applicant provide a trail through the wetland buffer as depicted on the plan. We have moved this trail to the north, splitting the buffer area between the wetland creation area and Wetland B to the north to maximize distance of the trail from the wetland as best possible. Signage and a split rail fence along the trail indicates the character of the critical area and will discourage intrusion into the wetland or buffer. All lighting will be located outside the wetland and buffer. All lighting in the developed portion of the site will be directed away from the wetland and its associated buffer. Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 12 The goal will be to create at least 25,430sf of area meeting all three wetland criteria (hydric soils, hydrophytic vegetation, and wetland hydrology) as specified in the Washington State Wetlands Identification Manual (W ADOE, March 1997) and the Western Mountain.v, Valleys and Coast region Supplement (Version 2.0) dated June 24, 2010. All disturbed buffer areas will be restored with a dense planting of native trees and shrubs. The resulting wetland creation area will be monitored for 10 years. The creation area will be delineated at Years 5 and IO to determine if 25,430sf of area meeting wetland criteria has been created. If there is not at least 25,430sf of wetland created, the shortage will be made up with either; I. Fixing any small grading or hydrology issue which may be impacting the overall size of the creation area, or; 2. Purchase of mitigation credits from the King County Fee program or other similar program at that time. Site Protection Instrument The entire mitigation site as well as the buffer and undisturbed wetlands will be placed within a Native Growth Protection Easement (N GPE) and recorded on title prior to occupancy of the project. Long Term Maintenance The mitigation area will be monitored and maintained over the IO year monitoring period. This will include trash removal, weed and invasive species removal, repair of fencing and signage. After the required 10 years maintenance and monitoring period, the facility operating manual will include a description of the NGPE are and what type of maintenance can and should occur within this area. Management of the facility will be responsible for this work following the IO year monitoring and maintenance period. PROPOSED MITIGATION • Fieldbrook!# 11-121 Sewall Wetland Consulting, Inc. 1.0 MITIGATION PROJECT OVERVIEW February 24, 2014 Page 13 To compensate for the fill of a 9,334sf Category III & IV wetlands, it is proposed to create 25,430sf of wetland between Wetlands A and C. Wetlands to be filled include Wetland D (7,67lsfCategory III wetland), Wetland E (68sfCategory IV wetland) & Wetland F (l,595sfcategory III wetland). 2.0 MITIGATION GOALS 2.1 Mitigation Goals The mitigation proposal is to connect Wetlands A and C with an area of25,430sf of wetland. The wetland creation areas will be densely planted with native vegetation. The use of diverse native plantings are expected to significantly improve the overall function of the wetland and buffer as it will remove dense thickets of exotic blackberry as well as add emergent and shrub plant communities into what is now, a single class forested wetland. 2. 2 Mitigation Goals 2.2.1 Create 25,430sf of emergent, scrub shrub and forested wetland. 3.0 CONSTRUCTION SEQUENCE The construction sequence of this project will be implemented as follows: 3.1 Pre-construction meeting 3.2 Construction staking 3.3 Construction fencing and erosion control 3 .4 Clearing and grading 3.5 Stabilization of mitigation area 3 .6 Plant material installation 3. 7 Construction inspection 3.8 Agency approval 3.9 10 year Monitoring inspection and reporting 3.10 Silt fence removal 3.11 Project completion 3.1 Pre-construction Meeting A pre-construction meeting will be held on-site prior to commencement of construction, to include the biologist, the City, and the contractor. The approved plans and specifications will be reviewed to ensure that all parties involved understand the intent of the construction documents, specifications, site environmental constraints, sequences, and inspection requirements. 3.2 Construction Staking Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 14 The limits of clearing and grading near the critical areas will be marked in the field by a licensed professional land surveyor prior to commencement of construction activities. 3.3 Construction Fencing & Erosion Control All erosion control measures adjacent to the critical areas, including silt fencing and orange construction fencing, will be installed. Erosion control fencing will remain around the mitigation area until clearing, grading and mulch placement are complete in upland areas outside the critical areas. 3.4 Clearing & Grading Clearing and grading in and near the existing sensitive area will be per the approved Final Mitigation Plans. 3. 5 Stabilization of Mitigation Area All graded areas in the wetland or buffer will be stabilized with mulch upon completion of grading. Orange construction fencing and erosion control fences will be restored (if necessary) and placed around the critical areas. 3.6 Plant Material Installation All plant material will be planted by hand per detail and Construction and Planting Notes. The Mitigation Plan specifies the required size, species, quantity, and location of plant materials to be installed. The contractor will mulch areas disturbed during the planting process. Upon completion of the planting, the erosion control fencing will be restored and repaired. Plant substitutions or modifications to locations shall be approved in writing by the Owner's biologist prior to installation. 3. 7 Construction Inspection Upon completion of installation, the biologist will conduct an inspection to confirm proper implementation of the Mitigation Plan. Any corrections, substitutions or missing items will be identified in a "punch list" for the landscape contractor. Items of particular importance will be soils in pits, pit size, plant species, plant size, mulch around pits, and tree staking. Upon completion of planting, if installation or materials vary significantly from the Mitigation Plan, the contractor will submit a reproducible "as-built" drawing to the Owner. The As-built and installation sign-off report will be submitted to the Corps at that time. 3. 8 Agency Approval Following acceptance of the installation by the City, the City biologist should prepare a letter granting approval of the installation. 3.9 Monitoring Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 15 The site will be monitored for 10 years to insure the success of the mitigation project. If additional years of monitoring are required by the Corps, the plan will be revised to reflect this change. Any areas of temporary impacts that require restoration will be also monitored for the full 10 year monitoring period. 3.10 Silt Fence Removal Erosion control fencing adjacent to the mitigation area will remain in place for at least one year, and/or until all areas adjacent to the mitigation area have been stabilized. The City's Biologist may recommend that the fencing remain in place for a longer duration. 4.0 CONSTRUCTION AND PLANTING NOTES 4.1 Site Preparation & Grading 4.1.1 The Landscape Contractor will approve existing conditions of subgrade prior to initiation of any mitigation installation work. The Landscape Contractor will inform the Owner of any discrepancies between the approved construction document and existing conditions. 4.1.2 The General Contractor will flag the limits of clearing with orange construction fencing and will observe these limits during construction. No natural features or vegetation will be disturbed beyond the designated "limits of clearing". 4.1.3 The Landscape Contractor will hand grub all non-native invasive plant species including the removal of root crowns. These species may include, but are not limited to Himalayan blackberry, evergreen blackberry, English ivy, and English holly. Weed debris will be disposed of off-site. 4.1.4 The wetland area will be excavated to the depths shown on the Final Mitigation Grading Plan and brought to final grade with 8" of topsoil. The biologist will be on-site to confirrn the grading is acceptable for planting. A total of 4"-6" of compost will be incorporated into the upper 12" of all graded areas in the wetland creation area. 4.2 Plant Materials 4.2.1 All plant materials will be as specified in the plant schedule. Only vigorous plants free of defects, diseases and infestation are acceptable for installation. 4.2.2 All plant materials will conforrn to the standards and size requirements of ANSI Z60. l "American Standard for Nursery Stock". All plant materials will be native to the northwest, and preferably the Puget Sound Region. Plant materials will be propagated from native stock; no cultivars or horticultural varieties will be allowed. All plant materials will be grown from nursery stock unless otherwise approved. • Fieldbrook/# 11-12 l Sewall Wetland Consulting, Inc. February 24, 2014 Page 16 4.2.3 No balled and burlapped, or bare root plantings will be used. Only container stock to be used. 4.2.4 All plant materials stored on-site longer than two (2) weeks will be organized in rows and maintained by the contractor at no additional cost to the owner. Plant materials temporarily stored will be subject to inspection and approval prior to installation. 4.2.5 Substitution requests must be submitted in writing to the Owner and approved by the Owner's biologist in writing prior to delivery to site. 4.2.6 All plant materials will be dug, packed, transported and handled with care to ensure protection from injury. All plant materials to be stored on site more than 24 hours will be heeled into topsoil or sawdust. Precautionary measures shall be taken to ensure plant materials do not dry out before planting. Wetland plants will be shaded and saturated until time of installation. Immediately after installation the mitigation planting area will be saturated to avoid capillary stress. 4.2.7 The contractor will verify all plant materials, the quantities shown on the planting plan, and the plant schedule. The quantity of plant materials shown on the plan takes precedent over the quantity on the plant list. 4.3 Plant Installation 4.3. l All plant materials must be inspected prior to installation to verify conformance of the materials with the plant schedule including size, quality and quantity. Any plant or habitat materials deemed unsatisfactory will be rejected. 4.3.2 All plant materials delivered and accepted should be planted immediately as depicted on the mitigation plan. Plant materials not planted within 24 hours will be heeled-in. Plant materials stored under temporary conditions will be the sole responsibility of the contractor. Plants will be protected at all times to prevent the root ball from drying out before, during, or after planting. 4.3.3 All planting pits will be circular with vertical sides, and will be sized per detail on the mitigation plan and filled with pit soils approved by the Owner's biologist. Planting pits shall not be deeper than the root ball. If native soils are determined to be unacceptable by the Owner's biologist, pit soils will be amended with Cedar Grove mulch or equivalent. 4.3.4 No fertilizers will be used within the wetland. In buffer areas only, install "Agriform", or equal plant fertilizer to all planting pits as specified by manufacturer. Fertilizers are allowed only below grade in the planting pits in the buffer areas. No sewage sludge fertilizer ("SteerCo" or "Growco") is allowed in the mitigation area. Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 17 4.3.5 All containerized plant materials will be removed from their containers carefully to prevent damage to the plant and its roots. Plants removed from their containers will be planted immediately. 4.3.6 All plant materials will be placed as shown on the approved mitigation plan. If the final installation varies from the approved mitigation plan, the contractor will provide a reproducible mylar as-built of the installed conditions. All plant material will be flagged by the contractor. 4.4 Planting Schedule and Warranty 4.4.1 A fall-winter installation schedule (October I st -March 15th) is preferred for lower mortality rates of new plantings. If plant installation occurs during the spring or summer (March 15th -Oct. 1st) a temporary irrigation system will be required, unless the area can be sufficiently hand-watered. 4.4.2 All disturbed areas will be protected with an arborists mulch to a minimum depth of six inches. 4.4.3 The installer will warrant all plant materials to remain healthy and alive for a period of one year after final acceptance. The installer will replace all dead or unhealthy plant materials per the approved plans and specifications. 4.5 Site Conditions 4.5.1 The installer will coordinate with the Owner and the Owner's biologist for construction scheduling. 4.5.2 Landscape installation will begin after the City acceptance of grading and construction. The Owner will notify the Owner's biologist of acceptance of final grading. 4.5.3 Silt fences will be installed as shown on the approved mitigation grading plans. The installer is responsible for repair and replacement of silt fences disturbed during plant installation. No equipment or soils will be stored inside the silt fences. 4.5.4 After clearing and grading is complete in the mitigation area, exposed soils will be seeded or mulched. Orange construction fence will be placed around the mitigation area to prohibit equipment and personnel in the mitigation area. 4.5.5 Final grading will be based upon soil conditions found during excavation of the mitigation area. Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 18 4.5.6 All plant material will be planted with suitable soils per planting details. Soils from planting holes will be spread and smoothed across the mitigation area. 5.0 MAINTENANCE PROGRAM This maintenance program outlines the program, procedures and goals for mitigation of the stream and buffer impacts at the mitigation site. This maintenance program will be the responsibility of the project owner through the duration of its ownership of the mitigation area, or throughout the duration of the monitoring period, whichever is longer. The maintenance contractor will complete the work as outlined below. 5.1 Maintenance Work Scope 5.1.1 To accomplish the mitigation goals, normal landscaping methods must be modified to include: a.No mowing or trimming of ground cover or vegetation in the mitigation area. b. No placement of fertilizers in the mitigation area. c. No placement of bark mulch or equivalent in the mitigation area, except as noted in the planting details. d. No placement of grass clippings, landscape debris, fill or ornamental plant materials in the mitigation area. 5.1.2 Work to be included in each site visit: a. Remove all litter including paper, plastic, bottles, construction debris, yard debris, etc. b. Remove all non-native and invasive species identified in Table 3-1 of Sheet W-3 of the Final Mitigation Plan within the mitigation area. All debris is to be removed from site and disposed in an approved landfill. c. Repair silt and/or permanent fencing and signage as needed. 5.1.3 Work to be completed on an annual basis includes: a. Areas containing non-native/invasive species identified in Table 3-1 of Sheet W-3 of the Final Mitigation Plan should be controlled by hand cutting and removing the root crowns for species such as Himalayan blackberry. Following hand removal, treating re-sprouting invasive/non-native species with a glyphosphate herbicide such as Roundup or Rodeo by a licensed applicator can be utilized. b. Replace dead or failed plant materials. Replacement plantings are to be of same species, size and location as original plantings. Plantings are to be installed during the dormant period. 5.2 Maintenance Schedule Fieldbrook/# 11-121 Sewall Wetland Consu !ting, Inc. February 24, 2014 Page 19 The Owner will conduct all items listed in the Maintenance Work Scope on an annual basis. Additional work may be required per the Monitoring Report and as approved by the Corps. Additional work may include removal of the grasses around each shrub and tree, installation of wood chips at each shrub and tree base and erosion control protection. 5.3 Watering Requirements 5.3.1 Watering with a temporary irrigation system will be required during the first spring and summer after the installation. The temporary irrigation system may be removed after the first year providing the plantings are established and acclimated to on- site conditions. 5.4 Close-out of Ten-Year Monitoring Program Upon completion of the monitoring program and acceptance of the wetland mitigation by the Corps, the maintenance of the project will be reduced to include removal oflitter and debris, repair of perimeter fencing and signage, removal of noxious weeds and undesirable vegetation, and repair of vandalized areas. 6.0 WETLAND AND BUFFER 10 YEAR MONITORING PROGRAM 6.1 Sampling Methodology The created wetlands and their associated buffers will be monitored once per year over a ten-year period, starting with the first year after the plants have been installed, and as required by the Corps. Monitoring will be conducted using the techniques and procedures described below to quantify the survival and relative health and growth of plant material. A monitoring report submitted following each monitoring visit will describe and quantify the status of the mitigation at that time. Vegetation monitoring will be conducted in August or September during monitoring years. Year 1 monitoring will occur at least one calendar year after installation sign-off. 6.1.1 Hydrology Wetland hydrology will be monitored using seven (7) piezometers per USACOE specifications. These will be located within the restoration area to be placed at the time of the installation sign-off by the biologist. Surface water level or ground water saturation depths will be measured at these stations to determine if wetland hydrology has been successfully attained. As is noted in the Corps of Engineers Wetlands Delineation Manual (Environmental Laboratory, 1987) and the Western Mountains, Valleys and Coast region Supplement (Version 2.0) dated June 24, 2010, wetland hydrology is defined as inundation or soil saturation (usually within 12" of the surface) during the growing season. The growing season for this area is generally defined as the period ' Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 20 between the middle of March and the middle of November. However, plant growth often occurs earlier in the year and sound professional judgment will be needed to determine when the growing season is taking place at the site. Hydrology will be monitored twice a month from March I st through May 30th of each year. Wetland hydrology will be considered successfully created if wetland hydrology is observed inundating or saturating the soil within 12 inches of the surface during the growing season 6.1.2 Vegetation The vegetation monitoring consists of inspection of the planted material in late summer or early fall (August-September) to determine the health and vigor of the installation, as well as coverage estimates. All the planted material in the wetland and buffer will be inspected during each monitoring visit to determine the level of survival of the installation. All plants will be inspected and recorded as to whether they are alive or dead based upon the "as-built" in Years 1 & 2. In Years 3-5, coverage estimates will be used to determine success of the vegetation component. A total of 19 permanent 3.0m rectangular monitoring plots will be located within the mitigation area as depicted on Sheet W-3 to monitor shrub and tree species coverages. Within each of these 3.0m plots, the emergent plant community coverage of vegetation will be measured with 0.25m rectangular plots. Estimates of coverage percentages will be made within these plots. Photographs of the mitigation area will be taken from 6 photo points to be located during the installation sign off as well as at each permanent monitoring plot. Photographs will be taken at each of the monitoring and included with the monitoring report for each year from these points. During years 1 & 2 of the monitoring, replacement plants as well as dead plants will be flagged with distinctive flagging to distinguish what plants these are. ' Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 21 6.2 STANDARDS OF SUCCESS PERFORMANCE STANDARDS ITtM YlAlS TO II MOM1'0lt& POfOIMANCI ITANDMI) Wll\AND H'tDROlOGY 'VEAR$ 1, 2. !, 4, S. 7 .tiND 10 SOlLS WITHIN CREATED WETlAHD WAS SttAl..l.1£ SATUR.ATtDTOfflE SUUltl:f., HAvt SHALLOW (CRtAflD WITlAND AND GAOUNDWATtll ftfl[S[NTWITH .. 12 INCHCS Of THC SOit Sllftf~E,~ HAV£ $UflFAf.£ JrONDING WUl.ANO "J'WETI.NID q P'RlstNT roR Af UAST FOOR (4) CONSEClJJIVE Wt:EICS DURING THE SIASON WHEN RAINfALL 15 LISS THAN OR EQUAL TO THI MlAN FOR THE PII\IOO Of AVAN.Allf RECORD. wrnAND D£UNEATl0N YEAII.S 5 i6.N010 PERFORM Df:UNEATION Of WETlAHO A. Wm.AND C, AND wtllAND CREATION Nl£A TO OlTEUl'INE IF WHETHER Wm.AND A ANO Wm.AND CAM: -YKCTED flYTHE WETLAND otEA.TlON. PERFO'™ANCE STANO.UO 15.s.t.TIYIED IF THERE IS NO CHANG£ TO WfllAND llMITS, NATIV£ YEGUAflON Y'£MS 1, l, S, 4, S. 7 AND 10 TREE ~O SHU SPECIES (atEA TED WETlANO/ (TO OCCUR IN AUGUST OIi . looi i.Hi\lNM. iv MT Al.LED PWfTSTOo: NTER THE RRST GltOWING SEASON . ENHANCEOW£l\AHO llUFFEI) SEPTEM&n l!GINNNG ONf . '°" SIJRYfYAL IY INSTAllED Pl.ANT STOO: AFJEII. TltE S£CONOGROWING SEASON. 't't.U. JOUOWlNG lNITIAL . INHANCKl IUfflfll P'I.ANT1Nli AIIIIAS: MINIMUM PHlaNT COVER IY TUfS AND SHRIJ8S: Y1:AR 3: rLANT INSTAUATION.) J091i; VEAi $; "'S"; 'tEAII. 7: 6S"; YEAR 10; ""6. IJf' TO 20" OF THE NATIV( WOOOY PlANT SPECIES COVfRAGE MAY BE COMPRISED Of ~JtABlE NATM COlO..ZING 5'EOES. . CMAllOWITUNO Pl..f.NTIMMIAS; MIHIMUM N-«NT COYElt lY TM ES ANO SHRUIS: V£AA S: '°"; YEM S: SOM; Y!Alt 7: IIO!'; YlM 10: !111%. Uf' TO 2°" OF THE NATIVE WOOO'I' PLANTSPfOES COV£MGE MAY If COMnlSlD Of D£SIM1lE NA TM COI..ONIZING 5'£0ES. . AFTEJI. THE RFTH GflOWING SEASON, A MINIMUM Of FOUi\ DIFFEtENT PlANT 5PECIES Will COMPJISE GRfA.lEII; TKAN 1QKCOY'Ell;A6£. [MEll6.NT Sl'ECIES • 25 AviMGf. COVEAAGE IV INSTAU.ED PU.NT Sl00: AFTER THE RfCST 6ROWlrfG SEASON. . 80% AV£UGE. COYEMGE IY INS TAI.LEO PlAHT SlOO: AFUl lHE 5th 6: 7tk ~ MUOU. • ~AVfll;AG£C0YlkAGtlVNATM IMIR61:NT PLANTS,IOESNTEA rtef TH NG SEASON . . AfffR THE FtHH GROWING SlASON, A MINIMUM Of THJI.IE OtfffRINT PLANT sPiCIIS WlU. COMPfUSEGIIIATER THAN 1°"COVIRAGE, 1tn,U, l, S. .. , ).11•,JIIII .W NA'fIV[ VtG!TATION (fl!I «aJI Ill AU.ilutt ~ . 100% SUJlVIVAl lY IHSTAL1.ED PLANT STOCI( Af-THI ntE Fifi.ST GROWING SEASON . IIY'Ol:Mll,Pll:91Nl'Ki:,tlll 80% SURVIVAL IY INSTMl.10 P\ANT $TOO.: NTEJt THE Tfflfl.D GfWWIN<i 5iA50N. (RlSTORID WULANO IUFFH) "IIUf(l.~NO""'lllil . HMl lfDIM.V..100 LfSS THAN tO!lo COY!IAGl IV Alt Cl.ASS "A". •r, AND MC" NOXIOU$ WUDS IINClUOING NOM-ltt:GUlATID NOXIOUS WfEO S,£C16 Vf:ARS 1, 2. J, 4. !, 7. AND 10 "I" AND "C" NOXIOUS WilD5) K>fNTIFED ON THI LATUf KING COUNTY NOXIOUS WiiD UST. N0J00US WHO CONTROl PERfOAMANCE ST ANDI.RDS AM. UMITIO TO Pl.ANTED AREAS ONLY. 7.0 CONTINGENCY PLAN 7.1 A contingency plan can be implemented if necessary. Contingency plans can include re-grading, additional plant installation, erosion control, modifications to hydrology, and plant substitutions including type, size, and location. 7 .2 Careful attention to maintenance is essential in ensuring that problems do not arise. Should any of the site fail to meet the success criteria, a contingency plan will be developed and implemented with the City approval. Such plans are prepared on a case- by-case basis to reflect the failed mitigation characteristics. 7.3 Contingency/maintenance activities will include, but are not limited to: -Replacing all plants lost to vandalism, drought, or disease, as necessary. -Replacing any plant species with a 20 percent or greater mortality rate with the same species or similar species approved by the City Biologist. r • ; Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 22 -Irrigating the mitigation area only as necessary during dry weather if plants appear to be too dry, with a minimal quantity of water. -Reseeding wetland and buffer areas with an approved grass mixture as necessary if erosion/sedimentation occurs. -Removing all trash or undesirable debris from the wetland and buffer areas as necessary. If you have any questions regarding this report, please call us at (253) 859-0515 or at esewall@sewallwc.com . Sincerely, Sewall Wetland Consulting, Inc. Ed Sewall Senior Wetlands Ecologist PWS #212 Sewall Wetland Consultin Inc. PNW HOLDINGS LLC -FIELD BROOK COMMONS CITY OF RENTON Sewall Wetland Consulting, Inc. 27641 Covington Way SE, #2 Covington, WA 98042 MITIGATION PLAN 2-24-2014 NWS-2012-1281 Prepared For: PNW Holdings, LLC 9675 SE 36th Street Suite 105 Mercer Island, Washington 98040 Attn: Justin Lagers February 24, 2014 Job#ll-21 FEB 2 6 2014 Phone: 253-859-0515 Fax: 253-852-4732 Sewall Wetland Consulting, Inc. 27641 Covington Way SE #2 Covington WA ~ PNW HOLDINGS LLC -FIELD BROOK COMMONS CITY OF RENTON 1.0 INTRODUCTION MITIGATION PLAN 2-24-2014 NWS-2012-1281 Phore: 253-859-0515 Fax: 253-S52-4Z32 This report describes the proposed wetland mitigation for the Fieldbrook Commons PUD project, located on the east side of Benson Road South, and north of Cedar Avenue South (SE 172nd Street) in the City of Renton, Washington (the "site"). 2.0 PROPOSED PROJECT & MITIGATION SEQUENCING The purpose of the proposed project is to construct a multi-family apartment complex as the property has been zoned for, as well as planned for in the City of Renton Comprehensive plan. The need for apartment units within Renton is high and this project has been proposed to meet that need. The proposed project is the construction ofa 161 PUD project with associated infrastructure. The location of Wetlands D, E and F result in most of the developable property on the site being encumbered by wetland or buffer. Since these wetlands, particularly Wetlands E and Fare of low value, and Wetland Dis small in size but because of its linear shape impacts the sites usable space so greatly, we are proposing filling these three wetlands. As a result, it is our intention to fill these wetlands and provide adequate mitigation for their lost functions by creating wetland on the eastern side of the site in and around Wetlands A, Band C. Impacts to wetlands must be justified through a mitigation sequence as detailed in City of Renton Code. Ideally we would be able to use the King County fee mitigation banking process as is preferred by the Corps and W ADOE. We are in agreement that using the fee-in-lieu mitigation option would be ideal and the easiest/fastest way to mitigate the proposed impacts. However, the City of Renton has refused to let us use this as a mitigation option as it moves the mitigation area outside the City limits and in their opinion is a net loss of critical areas to the City. It appears the City looks at the mitigation, and trail through the buffer as part of the "public benefit" aspect of this project. The construction of the mitigation onsite, as well as the placement of a trail through the buffer are being required by the City to allow us to construct this Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 2 project. It is our opinion that the trail does increase the amount of human intrusion into the wetland, and would be best left off the plan. However, the City of Renton will not accept this and are forcing us to bring a trail through the buffer regardless of the logic. The next best option is on-site replacement of the wetland area and functions as proposed in our mitigation plan. The attached mitigation plan has been prepared with the recommended documents elements as requested by Suzanne Anderson of the US Army Corps of Engineers in previous comments. This plan is prepared in the exact same manner and with the same information as numerous mitigation plans we have submitted and had approved by the Corps for various Nationwide as well as Individual Permits. As requested the monitoring has been modified to include I Oyears of monitoring. (c) Per the Fcdcral Mitigation Rule, you must provide additional information to document that a Wlltel'llhcd approach to compensatory mitigation was used for the mitigation plan [33 CFR 332.3(c)J. A linlt to Wtttland M/Jlgation Situ Using a Watttrsht!d Approach. Ecology Publication #09-06-032 is available from our webpage at www.nws.usace.anny.mil, select "Regulatory Branch, Permit Information", then "Mitiption R.csources", then "Mitigation Tools". We recommend that you demonstrate that the chosen mitigation site satisfies criteria in Charts 2 and 3 of the site selection guidance (i.e., identified as a site with potential and that is sustainable); and that it satisfies criteria in Charts 4 through 11 for the appropriate fimc:tions. Using Chart 2 from the Watershed approach which is an analysis utilized to pick a mitigation site is not really applicable, as the City of Renton is requiring we conduct the mitigation on the site where the impact is occurring. In addition, there is no other available mitigation sites within this drainage basin that is owned by either the City or the client for use as a mitigation receiving site. Therefore, mitigating on-site is the only feasible alternative given these constraints. In regards to Chart 3; Question 3A: Identify the watershed processes that have been altered within the hydrologic unit where the mitigation site is located. Human activities can change watershed processes by changing water flows; introducing nutrients, pollutants, non-native species, and sediment; and by fragmenting habitats. Changes in these processes often create problems that can be improved through mitigation activities. To begin you need to identify the major landscape-scale problems (i.e., alterations to processes, not structure) that exist in the hydrologic unit where your site is found. This will help you identify which restoration or enhancement actions will be the most effective in that hydrologic unit. Check the appropriate column in the following table to identify problems that might exist. The last column notes if the altered process has already been identified in an existing watershed plan as a problem that needs to be addressed Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 3 The current flooding events within the Soos Creek drainage are generally not increasing due to the current use of modern stonn water facilities within the basin. However, there still is some increase as there is more water getting to the basin faster in stonn events. There is less eutrophication in rivers and streams in the basin primarily from removals of livestock and old septic systems. Water quality has been reduced in the basin to a degree. Some stream and bank erosion does occur within the basin. Habitat has become more fragmented as the area's population grows and more development occurs. Question 3B: Will the mitigation result in a wetland of the appropriate hydrogeomorpllic (HGM) class for the landscape setting? Wetland mitigation sites are sustainable only if the type of wetland being proposed is appropriate for its position in the landscape. The HGM classification of wetlands is based on characteristics of water movement and position in a landscape. Therefore, it can be used to idenlify appropriate wetland types for different locations in a hydrologic unit. Yes, we will be mitigating for depressional wetlands with a depressional wetland mitigation area. Question 3C: Will the primary source of water to the mitigation site be appropriate for the HGMclass? Groundwater and direct precipitation will be the source of hydrology for the wetland mitigation site as was the source for the impacted wetlands. Hydro logic monitoring of the mitigation site has shown that surficial groundwater elevations in the mitigation area will sufficiently hydrate the creation area with soils saturated to the surface and some standing water in the growing season. Question 3D: Will the site have an adequate supply of water to maintain a wetland without engineering the delivery of water that would require long term control or maintenance? The surficial groundwater monitoring and proposed grades should create a wetland area that will require no additional or artificial source of water to maintain its viability. It is thought that Wetland A which is located within the area of an old mine is discharging water from historic mining and as such there is an abundant supply of water in this area. Question 3E: Will the mitigation activities maintain hydric soill, if they exist, at the site? Removing hydric soils can decrease the potential for success of we/land restoration. Hydric soils often contain a seedbank of wetland plants that supplement any planting you may propose. Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 4 Hydric soils from the filled wetlands will be mixed with topsoil and utilized in the newly created wetland maintaining viable seedbanks. Question 3F: Can the mitigation be designed to control aggressive plant species? There is currently not a predominance of aggressive invasive or weedy species in the area of the proposed mitigation or the two wetlands that will be connected together with the creation. Standard invasive species control will be utilized in the mitigation area which has proven successful in other mitigation sites. Regarding the appropriate Charts 4-11; Cb,ut .$: Goal~ lmp10Ying H~·drology functiom in Depn:-s5ionill Systems Outside of floodplains .. .. -8(9;' ... .. . ... . ............ cOMtraintl May N posdlll to -,.,_ liydrolap: hadial, lllr fllall ffiUA 9elCl'iN '-* COMhillu. --~willlN (lot911P!~) ,.-..... .. a.11v.it1111e :llrlacil.k!Mlleeft~ lhM:an.cbMM!watet. t,DQlollffl~) Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 5 Chari".': Go;1J -ImprnYin:g \Yate,r Quality (\YQ) Functiom in Depn?ssional ~ystNm Out'i.ide of lloo(lplaim. . 111 ·--- Chart 10: Goal -lmpro,ing SpiKitis Ridllless of \Yildlift' C 11111(/1 .. ,1,~ e.aCOll'lilllrtll-" ·:::.::t.:-............ , CllllluflWfl ...... .....,_ ....... _ .. _ .. €) .. .. .. .. .. .. .. ... .. . '_ ' ,''; ,, . ; • -(]Ifft\!: • -.;.:.:. ~'ll~~wil-d -~·~-'"'*'-~-~-""*'*"' tp"' -IINODIIJ • Chart 1 l: C.oal Imp1·0\ing SJJede~ Rirhness of Plant~ --·- d••*••~ •• Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 6 -··-·- ........... ··· ... · . . . ' . ' ' . -'-wnine....,,.;.,,,;-' QMi.-i... ,.,..._ ..,,.1"llti11w#~nl-M..._IIM:Nil; ... ...-,....,.,.~ ..... Q'l"Yl'fll'~ __ ,yal'll,.._t.«hei-aai .... .,. .. _.,_..., This sequencing requires addressing the following criteria; a. Avoid any disturbances to the wetland or buffer; C.nlrel.,..,......qlNHw~,-,j• ...:I_.• --~.11:KciaW-ai years-~.-IPt,.liliAf.•..,.,... -.oi ... o,,ce ....-ed. I"-~ ..,....i.,.w...,_......1,y~ a,ty1.......,..1..,...1Mt...,_..,.. willl.,...,_""'llf!IDl:I. ••-......,I •li:aJ_R.....,..N!N'M;awNH;lna __.... ........ .-11 ... l'Vn.l ..... 0. ._.. .. i,'"""'.""" .-,.Sriclftul -~11:-.,...,..site.Li\Oe ........i--...illl~N•"Y~ = !::=:.":1..,-.::' =~ -- The site contains three small wetlands which the developer proposes to fill and mitigate for through the creation of a new wetland area and enhanced buffer areas for the existing and remaining wetlands A, B & C in the eastern third of the site. Wetland F located on the western side of the site is Category III wetland measuring 1595sf. Due to the requirement to provide a secondary fire access directly out to I 08 1h Ave S.E. the developer is unable to avoid direct impact to this wetland. Wetland E, located in the center of the site and adjacent to S.E. 172nd St. measures 68sf and is rated as a Category IV wetland. Due to the requirement to dedicate and construct the other half of the S.E. 172"d St. ROW the developer is unable to avoid direct impacts to this wetland. Wetland D is located generally in the center of the project and is rated as a Category III wetland measuring 767lsf. b. Minimize any wetland or buffer impacts; The developer previously attempted to plan roadways and improvements around Wetland D, however the location and shape of the wetland impacted the vehicular circulation and Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 7 building locations to such an extent that the project would not be financially feasible to construct. c. Restore any wetlands or buffer impacted or lost temporarily; and Restoration of Wetland Din this location would not be feasible due to the location of the impacts and configuartion of the parcel and remaining wetland. d. Compensate for any permanent wetland or buffer impacts by one of the following methods: i. Restoring a former wetland and provide buffers at a site once exhibiting wetland characteristics to compensate for wetlands lost; This is not applicable to this site as no historic wetlands are located on the property. ii. Creating new wetlands and buffers for those lost; and A total of9,334sfofwetland will be filled. US Army Corps of Engineers Required Mitigation Using the recommended ratios from Table la, of the W ADOE Publication Wetland Mitigation in Washington State Part 1, (WADOE March 2006 Pub. #06-06-01 Ja) Table 1 Wetland Size Category Vegetation Ratio Required Type Wetland Creation D 767lsf III Forested 2:1 15342sf E 68sf IV scrub-shrub 1.5:1 102sf F 1595sf Ill scrub-shrub 2:1 3190sf Total 9,334sf 18,634sf As described above, based upon the required USA COE and W ADOE ratio, a total of l 8,634sf of wetland is required to be created. Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 8 The proposed mitigation will create 25,430sf of wetland, which exceeds the required USACOE ratios by 6,796sf. The extra wetland being created over the WADOE recommended ratios is a result of the City of Renton having a higher mitigation ratio requirement than the Corps. As seen in Table 2 below, using the three main functions from the W ADOE Rating System recognized by the Corps, a substantial functional lift will be attained from the connection of Wetlands A and C with 25,430sf of additional wetland over the existing functions of the proposed fill wetlands. Tbl2F f IC a e unc 10na omoarison o f. d 1moact wet an s an d orooose d m,h ahon Wetland Area Flood Species Water Hydrologic Habitat Storage Richness Qual. Function Function capacitv Function WetlandD 7671sf 3800cuft 5 svecies 12vts 8vts 13vts WetlandE 68s( 34cuft 2 svecies llvts 4vts JOvts Wetland F 1595sf 500cufi 5 svecies 20pts 8vts llpts Provosed 25430sf 7600cuft 15 soecies 24ots 20ots 21 ots Functional +16096sf +3266cuft +8species* +9pts +12pts avg +9pts I Lift av!! av!! *only 7 different species were found (excluding exotic/invasives) in Wetlands D, E &F The newly created wetland will connect to existing Category lil wetlands (Wetlands A and C) and provide enough lift that this wetland will now be considered a Category II wetland under the W ADO£ rating system. This is a substantial lift in function, surface water storage and species richness over the fill of Wetlands D, E & F, which are generally low value Category III and JV wetlands. Hydrologic monitoring of mitigation site and general construction overview Category III IV ill 11 +1 Cate!!orv To compensate for the impact to 9,334sf of Category III & IV wetland, we will create 25,430sfofwetland between Wetlands A and C. This results in an overall wetland mitigation ratio of 2.72:1 (created wetland:impacted wetland). This mitigation will create Category II wetland for a combination of Category Ill and IV wetland impacts. As depicted on the attached Final Mitigation Plan, 25,430sf of area will be excavated out to a similar depth to the existing wetland in two areas to intercept the surficial groundwater table and create conditions favorable to create wetland hydrology. A series of 6 monitoring pits/wells were located within the proposed wetland mitigation area. These were monitored with weekly site visits from April of2012-August 2012 as well as March and early April of 2013. At each of these points soil saturation and water table levels were measured to determine what surficial groundwater elevations are, to facilitate designing grades for the new wetland creation area. What we found was that within the proposed creation area, groundwater levels in the early growing season area Fieldbrook/#11-121 Sewall \.Vetland Consulting, Inc. February 24, 2014 Page 9 between 14" -30" below the existing surface (see table below). It is assumed in the very early growing season (February and March) the groundwater elevations are shallower than the measurements we took, meaning the groundwater elevations are closer to the soil surface. As shown on the attached Final Mitigation Plan Sheets W I-W3, we utilized these existing groundwater contours to create the new grades for our mitigation site. As can be seen by the grades and associated cross-sections, the grades will remove soil down to the existing groundwater elevations to create wetland areas with soils saturated to the surface for the early growing seasons, to also include flat areas that will hold some shallow l "-3" of surface water to provide a variety of wetland hydro logic regimes from saturated, to seasonally flooded. The fact that the excavation is being brought to the higher levels of groundwater within the growing season, and will not cut into the surficial groundwater table, should alleviate the concern of intercepting and draining off this water. All we are doing is removing the surface soil above the existing sloping groundwater table to make those saturated soils closer to the surface. Soil disturbance of the groundwater retaining portion of the soil column will not occur. Although creation of a slope type wetland is not the most conventional or common mitigation method, it is a feasible method of wetland creation when conditions warrant its use. Our company has been involved in two larger wetland creations using this type of concept, most recently a 3 acre wetland creation with over 10' of vertical drop across the landscape in sloping of the creation area (see Snohomish County Parks Centennial Trail II mitigation plan reviewed and approved by Jonathan Smith of the Corps). By using the same method of removing soil down to the level of the highest groundwater elevations as is proposed in the Fieldbrook project, we successfully created a 3 acre sloping wetland in the previously described project. Table 3. Groundwater elevations below surface o 'hydro/o, v monitorin!! ooints 2012 Monitor DATE point& elev. 4/13 4/27 5/11 5/24 6/7 6/28 7/12 A417.5' -15 -14 -15 -20 -26 dry dry B418' -17 -16 -16 -22 -27 drv drv C417' -20 -18 -17 -20 -25 dry dry D416.5' -14 -14 -14 -16 -20 drv drv E418.5' -27 -26 -24 -30 -36 dry dry F418' -21 -22 -20 -28 -36 drv drv Note: All elevations indicate the elevation of the saturaled capillary fringe of soil saturation observed in hydrology monitoring points. 8/12 drv drv dry drv dry drv Table 4. Groundwater elevutions below surface o Monitor DATE point& elev. 3/15 3/29 4/9 A417.5' -12 -10 -15 B418' -15 -15 -14 C417' -17 -16 -18 0416.5' -10 -11 -13 E418.5' -23 -20 -23 F418' -18 -19 -20 Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24. 2014 Page 10 r hvdrolo• " monitorinf! ooints 2013 Note: All elevations indicate the elevation of the saturated capillary fringe of soil saturation observed in hydrology monitoring points. .......... . . . . . .. . . . . . . . . . . . . . . . . -. . . . . . ,.. . . . .. . . . . . . . • ,• ... . . . . . . . -" ..... . . . : . : . : . : . : . ·,.:. :..:: . : . : . : . : ...... / . .,-..... ... -:.:-:-:-:-: . .-:-:-:<-:::: ... •••••••• ••• ,!·~· •• •• /'. •••••••••• ... . ..... \ .... ,. . . . . . ~\ \ . . ..... . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . ...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. Erilting •uifaa 418A~~~~~Vtl~~~'-+--~~~~----sVtl,___~~~C l~I~ ::::::::::::::::::::::::::::::::~~::::~::::::::::~~,:;;:v=:~::::::::::::::::::::::::::::::::::::;;:.,::::~I :::::::::::::::::::::::::::;I A ~•urfaa 419~~~.,.Vtl~~~~'S,-->,---~~~~~~~~------'iB 1~1~~~~~~~~~~,....~~.;J,~~~'\~~~~~~~~~~~~,~~~~1 BA Vtl \ ...... February 24, 2014 Page 11 -•Apptoxirnat. groundwater .ievation D 41 41 41 41 41 41 41 411 7 6 ...... , 'I. .,, ...... / '\ ~ "' "' ...... 'I. ' 'I. -'I. -- A small berm will be placed between the wetland creation area and Wetland B. This will prevent (in the unlikely case of surface water overtopping the edge of the wetland) the wetland creation area between Wetlands A and C from draining into Wetland B. Hydro logic monitoring will be conducted using peizometers in the proposed mitigation area through the winter and spring to verify groundwater elevations. This area will then be graded back at a slope no steeper than 3:1 (horizontal:vertical). The area will then be planted with a mix of native trees, shrubs and herbaceous species and will also include several habitat features (logs and snags) to increase its habitat function. As depicted on the attached Fieldbrook Commons Mitigation & Grading Plan (dated 9- 23-13), a split rail fence will be placed at the edge of the wetland buffer. There are no living spaces or recreational space next to the wetland or its buffer limiting use of this area. However, the City of Renton is requiring that the applicant provide a trail through the wetland buffer as depicted on the plan. We have moved this trail to the north, splitting the buffer area between the wetland creation area and Wetland B to the north to maximize distance of the trail from the wetland as best possible. Signage and a split rail fence along the trail indicates the character of the critical area and will discourage intrusion into the wetland or buffer. All lighting will be located outside the wetland and buffer. All lighting in the developed portion of the site will be directed away from the wetland and its associated buffer. Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 12 The goal will be to create at least 25,430sf of area meeting all three wetland criteria (hydric soils, hydrophytic vegetation, and wetland hydrology) as specified in the Washington State Wetlands Identification Manual (W ADOE, March 1997) and the Western Mountains, Valleys and Coast region Supplement (Version 2.0) dated June 24, 2010. All disturbed buffer areas will be restored with a dense planting of native trees and shrubs. The resulting wetland creation area will be monitored for 10 years. The creation area will be delineated at Years 5 and 10 to determine if 25,430sf of area meeting wetland criteria has been created. If there is not at least 25,430sf of wetland created, the shortage will be made up with either; 1. Fixing any small grading or hydrology issue which may be impacting the overall size of the creation area, or; 2. Purchase of mitigation credits from the King County Fee program or other similar program at that time. Site Protection Instrument The entire mitigation site as well as the buffer and undisturbed wetlands will be placed within a Native Growth Protection Easement (NGPE) and recorded on title prior to occupancy of the project. Long Term Maintenance The mitigation area will be monitored and maintained over the 10 year monitoring period. This will include trash removal, weed and invasive species removal, repair of fencing and signage. After the required 10 years maintenance and monitoring period, the facility operating manual will include a description of the NGPE are and what type of maintenance can and should occur within this area. Management of the facility will be responsible for this work following the 10 year monitoring and maintenance period. PROPOSED MITIGATION Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. 1.0 MITIGATION PROJECT OVERVIEW February 24, 2014 Page 13 To compensate for the fill of a 9,334sf Category III & IV wetlands, it is proposed to create 25,430sf of wetland between Wetlands A and C. Wetlands to be filled include Wetland D (7,67lsfCategory III wetland), Wetland E (68sfCategory IV wetland) & Wetland F (l,595sfcategory III wetland). 2.0 MITIGATION GOALS 2.1 Mitigation Goals The mitigation proposal is to connect Wetlands A and C with an area of25,430sf of wetland. The wetland creation areas will be densely planted with native vegetation. The use of diverse native plantings are expected to significantly improve the overall function of the wetland and buffer as it will remove dense thickets of exotic blackberry as well as add emergent and shrub plant communities into what is now, a single class forested wetland. 2. 2 Mitigation Goals 2.2.1 Create 25,430sf of emergent, scrub shrub and forested wetland. 3.0 CONSTRUCTION SEQUENCE The construction sequence of this project will be implemented as follows: 3.1 Pre-construction meeting 3.2 Construction staking 3.3 Construction fencing and erosion control 3.4 Clearing and grading 3.5 Stabilization of mitigation area 3.6 Plant material installation 3. 7 Construction inspection 3.8 Agency approval 3. 9 10 year Monitoring inspection and reporting 3.10 Silt fence removal 3.11 Project completion 3.1 Pre-construction Meeting A pre-construction meeting will be held on-site prior to commencement of construction, to include the biologist, the City, and the contractor. The approved plans and specifications will be reviewed to ensure that all parties involved understand the intent of the construction documents, specifications, site environmental constraints, sequences, and inspection requirements. • 3.2 Construction Staking Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 14 The limits of clearing and grading near the critical areas will be marked in the field by a licensed professional land surveyor prior to commencement of construction activities. 3.3 Construction Fencing & Erosion Control All erosion control measures adjacent to the critical areas, including silt fencing and orange construction fencing, will be installed. Erosion control fencing will remain around the mitigation area until clearing, grading and mulch placement are complete in upland areas outside the critical areas. 3.4 Clearing & Grading Clearing and grading in and near the existing sensitive area will be per the approved Final Mitigation Plans. 3.5 Stabilization of Mitigation Area All graded areas in the wetland or buffer will be stabilized with mulch upon completion of grading. Orange construction fencing and erosion control fences will be restored (if necessary) and placed around the critical areas. 3.6 Plant Material Installation All plant material will be planted by hand per detail and Construction and Planting Notes. The Mitigation Plan specifies the required size, species, quantity, and location of plant materials to be installed. The contractor will mulch areas disturbed during the planting process. Upon completion of the planting, the erosion control fencing will be restored and repaired. Plant substitutions or modifications to locations shall be approved in writing by the Owner's biologist prior to installation. 3. 7 Construction Inspection Upon completion of installation, the biologist will conduct an inspection to confirm proper implementation of the Mitigation Plan. Any corrections, substitutions or missing items will be identified in a "punch list" for the landscape contractor. Items of particular importance will be soils in pits, pit size, plant species, plant size, mulch around pits, and tree staking. Upon completion of planting, if installation or materials vary significantly from the Mitigation Plan, the contractor will submit a reproducible "as-built" drawing to the Owner. The As-built and installation sign-off report will be submitted to the Corps at that time. 3. 8 Agency Approval Following acceptance of the installation by the City, the City biologist should prepare a letter granting approval of the installation. 3.9 Monitoring Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 15 The site will he monitored for IO years to insure the success of the mitigation project. If additional years of monitoring are required by the Corps, the plan will be revised to reflect this change. Any areas of temporary impacts that require restoration will be also monitored for the full IO year monitoring period. 3.10 Silt Fence Removal Erosion control fencing adjacent to the mitigation area will remain in place for at least one year, and/or until all areas adjacent to the mitigation area have been stabilized. The City's Biologist may recommend that the fencing remain in place for a longer duration. 4.0 CONSTRUCTION AND PLANTING NOTES 4.1 Site Preparation & Grading 4.1.1 The Landscape Contractor will approve existing conditions of subgrade prior to initiation of any mitigation installation work. The Landscape Contractor will inform the Owner of any discrepancies between the approved construction document and existing conditions. 4.1.2 The General Contractor will flag the limits of clearing with orange construction fencing and will observe these limits during construction. No natural features or vegetation will be disturbed beyond the designated "limits of clearing". 4.1.3 The Landscape Contractor will hand grub all non-native invasive plant species including the removal of root crowns. These species may include, but are not limited to Himalayan blackberry, evergreen blackberry, English ivy, and English holly. Weed debris will be disposed of off-site. 4.1.4 The wetland area will be excavated to the depths shown on the Final Mitigation Grading Plan and brought to final grade with 8" of topsoil. The biologist will be on-site to confirm the grading is acceptable for planting. A total of 4"-6" of compost will be incorporated into the upper 12" of all graded areas in the wetland creation area. 4.2 Plant Materials 4.2.1 All plant materials will be as specified in the plant schedule. Only vigorous plants free of defects, diseases and infestation are acceptable for installation. 4.2.2 All plant materials will conform to the standards and size requirements of ANSI Z60.l "American Standard for Nursery Stock". All plant materials will be native to the northwest, and preferably the Puget Sound Region. Plant materials will be propagated from native stock; no cultivars or horticultural varieties will be allowed. All plant materials will be grown from nursery stock unless otherwise approved. Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 16 4.2.3 No balled and burlapped, or bare root plantings will be used. Only container stock to be used. 4.2.4 All plant materials stored on-site longer than two (2) weeks will be organized in rows and maintained by the contractor at no additional cost to the owner. Plant materials temporarily stored will be subject to inspection and approval prior to installation. 4.2.5 Substitution requests must be submitted in writing to the Owner and approved by the Owner's biologist in writing prior to delivery to site. 4.2.6 All plant materials will be dug, packed, transported and handled with care to ensure protection from injury. All plant materials to be stored on site more than 24 hours will be heeled into topsoil or sawdust. Precautionary measures shall be taken to ensure plant materials do not dry out before planting. Wetland plants will be shaded and saturated until time of installation. Immediately after installation the mitigation planting area will be saturated to avoid capillary stress. 4.2.7 The contractor will verify all plant materials, the quantities shown on the planting plan, and the plant schedule. The quantity of plant materials shown on the plan takes precedent over the quantity on the plant list. 4.3 Plant Installation 4.3.1 All plant materials must be inspected prior to installation to verify conformance of the materials with the plant schedule including size, quality and quantity. Any plant or habitat materials deemed unsatisfactory will be rejected. 4.3.2 All plant materials delivered and accepted should be planted immediately as depicted on the mitigation plan. Plant materials not planted within 24 hours will be heeled-in. Plant materials stored under temporary conditions will be the sole responsibility of the contractor. Plants will be protected at all times to prevent the root ball from drying out before, during, or after planting. 4.3.3 All planting pits will be circular with vertical sides, and will be sized per detail on the mitigation plan and filled with pit soils approved by the Owner's biologist. Planting pits shall not be deeper than the root ball. If native soils are determined to be unacceptable by the Owner's biologist, pit soils will be amended with Cedar Grove mulch or equivalent. 4.3.4 No fertilizers will be used within the wetland. In buffer areas only, install "Agriform", or equal plant fertilizer to all planting pits as specified by manufacturer. Fertilizers are allowed only below grade in the planting pits in the buffer areas. No sewage sludge fertilizer ("SteerCo" or "Growco") is allowed in the mitigation area. -----------------------------, Fieldbrook/#11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 17 4.3.5 All containerized plant materials will be removed from their containers carefully to prevent damage to the plant and its roots. Plants removed from their containers will be planted immediately. 4.3.6 All plant materials will be placed as shown on the approved mitigation plan. If the final installation varies from the approved mitigation plan, the contractor will provide a reproducible mylar as-built of the installed conditions. All plant material will be flagged by the contractor. 4.4 Planting Schedule and Warranty 4.4.1 A fall-winter installation schedule (October I st -March 15th ) is preferred for lower mortality rates of new plantings. If plant installation occurs during the spring or summer (March 15th -Oct. 1st) a temporary irrigation system will be required, unless the area can be sufficiently hand-watered. 4.4.2 All disturbed areas will be protected with an arborists mulch to a minimum depth of six inches. 4.4.3 The installer will warrant all plant materials to remain healthy and alive for a period of one year after final acceptance. The installer will replace all dead or unhealthy plant materials per the approved plans and specifications. 4.5 Site Conditions 4.5.1 The installer will coordinate with the Owner and the Owner's biologist for construction scheduling. 4.5.2 Landscape installation will begin after the City acceptance of grading and construction. The Owner will notify the Owner's biologist of acceptance of final grading. 4.5.3 Silt fences will be installed as shown on the approved mitigation grading plans. The installer is responsible for repair and replacement of silt fences disturbed during plant installation. No equipment or soils will be stored inside the silt fences. 4.5.4 After clearing and grading is complete in the mitigation area, exposed soils will be seeded or mulched. Orange construction fence will be placed around the mitigation area to prohibit equipment and personnel in the mitigation area. 4.5.5 Final grading will be based upon soil conditions found during excavation of the mitigation area. a • Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 18 4.5.6 All plant material will be planted with suitable soils per planting details. Soils from planting holes will be spread and smoothed across the mitigation area. 5.0 MAINTENANCE PROGRAM This maintenance program outlines the program, procedures and goals for mitigation of the stream and buffer impacts at the mitigation site. This maintenance program will be the responsibility of the project owner through the duration of its ownership of the mitigation area, or throughout the duration of the monitoring period, whichever is longer. The maintenance contractor will complete the work as outlined below. 5.1 Maintenance Work Scope 5.1.1 To accomplish the mitigation goals, normal landscaping methods must be modified to include: a.No mowing or trimming of ground cover or vegetation in the mitigation area. b. No placement of fertilizers in the mitigation area. c. No placement of bark mulch or equivalent in the mitigation area, except as noted in the planting details. d. No placement of grass clippings, landscape debris, fill or ornamental plant materials in the mitigation area. 5.1.2 Work to be included in each site visit: a. Remove all litter including paper, plastic, bottles, construction debris, yard debris, etc. b. Remove all non-native and invasive species identified in Table 3-1 of Sheet W-3 of the Final Mitigation Plan within the mitigation area. All debris is to be removed from site and disposed in an approved landfill. c. Repair silt and/or permanent fencing and signage as needed. 5.1.3 Work to be completed on an annual basis includes: a. Areas containing non-native/invasive species identified in Table 3-1 of Sheet W-3 of the Final Mitigation Plan should be controlled by hand cutting and removing the root crowns for species such as Himalayan blackberry. Following hand removal, treating re-sprouting invasive/non-native species with a glyphosphate herbicide such as Roundup or Rodeo by a licensed applicator can be utilized. b. Replace dead or failed plant materials. Replacement plantings are to be of same species, size and location as original plantings. Plantings are to be installed during the dormant period. • • 5.2 Maintenance Schedule Fieldbrook/#11-121 Sewall Wetland Consulting, Inc, February 24, 2014 Page 19 The Owner will conduct all items listed in the Maintenance Work Scope on an annual basis. Additional work may be required per the Monitoring Report and as approved by the Corps. Additional work may include removal of the grasses around each shrub and tree, installation of wood chips at each shrub and tree base and erosion control protection. 5.3 Watering Requirements 5.3.1 Watering with a temporary irrigation system will be required during the first spring and summer after the installation. The temporary irrigation system may be removed after the first year providing the plantings are established and acclimated to on- site conditions. 5.4 Close-out of Ten-Year Monitoring Program Upon completion of the monitoring program and acceptance of the wetland mitigation by the Corps, the maintenance of the project will be reduced to include removal of litter and debris, repair of perimeter fencing and signage, removal of noxious weeds and undesirable vegetation, and repair of vandalized areas. 6.0 WETLAND AND BUFFER 10 YEAR MONITORING PROGRAM 6.1 Sampling Methodology The created wetlands and their associated buffers will be monitored once per year over a ten-year period, starting with the first year after the plants have been installed, and as required by the Corps. Monitoring will be conducted using the techniques and procedures described below to quantify the survival and relative health and growth of plant material. A monitoring report submitted following each monitoring visit will describe and quantify the status of the mitigation at that time. Vegetation monitoring will be conducted in August or September during monitoring years. Year 1 monitoring will occur at least one calendar year after installation sign-off. 6.1.1 Hydrology Wetland hydrology will be monitored using seven (7) piezometers per USACOE specifications. These will be located within the restoration area to be placed at the time of the installation sign-off by the biologist. Surface water level or ground water saturation depths will be measured at these stations to determine if wetland hydrology has been successfully attained. As is noted in the Corps of Engineers Wetlands Delineation Manual (Environmental Laboratory, 1987) and the Western Mountains, Valleys and Coast region Supplement (Version 2.0) dated June 24, 2010, wetland hydrology is defined as inundation or soil saturation (usually within 12" of the surface) during the growing season. The growing season for this area is generally defined as the period . . Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 20 between the middle of March and the middle of November. However, plant growth often occurs earlier in the year and sound professional judgment will be needed to determine when the growing season is taking place at the site. Hydrology will be monitored twice a month from March I st through May 30th of each year. Wetland hydrology will be considered successfully created if wetland hydrology is observed inundating or saturating the soil within 12 inches of the surface during the growmg season 6. l.2 Vegetation The vegetation monitoring consists of inspection of the planted material in late summer or early fall (August-September) to determine the health and vigor of the installation, as well as coverage estimates. All the planted material in the wetland and buffer will be inspected during each monitoring visit to determine the level of survival of the installation. All plants will be inspected and recorded as to whether they are alive or dead based upon the "as-built" in Years I & 2. In Years 3-5, coverage estimates will be used to determine success of the vegetation component. A total of 19 permanent 3.0m rectangular monitoring plots will be located within the mitigation area as depicted on Sheet W-3 to monitor shrub and tree species coverages. Within each of these 3.0m plots, the emergent plant community coverage of vegetation will be measured with 0.25m rectangular plots. Estimates of coverage percentages will be made within these plots. Photographs of the mitigation area will be taken from 6 photo points to be located during the installation sign off as well as at each permanent monitoring plot. Photographs will be taken at each of the monitoring and included with the monitoring report for each year from these points. During years 1 & 2 of the monitoring, replacement plants as well as dead plants will be flagged with distinctive flagging to distinguish what plants these are. ,, Fieldbrook/#11-121 Sewall Wetland Consulting, Inc February 24, 2014 Page 21 6.2 STANDARDS OF SUCCESS PERFORMANCE STANDARDS ITIM YUM TO ll MONITOND ........_, .. _ wnt.AND HYDAOLOGY YEA.RS l, 2, J, 4. 5, 7 AND 10 SOILS WtTHIN CJl:EATU> Wtfl.ANO Aft(AS SHAU. IE SA'T\JRATUl TO TI-E SURFACE., HA\lt SHAU.OW ICUAHD WIT LAND AND GIIOUNDWA.Tlft i.ESCNT WITHIN 12 INOIESOI' THE SOil 5URFI£[, AND/Oft HAVE SURFAC.E PONDING WETlAND A/WETlAND C) PRESENT FOR. A.T LEAST FOUR (4) CONSf:CUTIVE WIU:S OUFUNG THE GIOWIHG SlASON WHEN M.!Nf:.IJJ. IS LESS TAAN OR EQUAL TO TH£ MEAN FOR THE Pf.RIOO OF·A\IAILAIU RECORD. W£TlAND D£UNEAT10N VU.RS SAND 10 PERFORM OElWEATION Of WeT\ANO A, WETLAND C, AND WE TI.AND at.EATION A/I.EA lO OETEAMINE If. WHnHER WETLAND A ANO WET\AND CME IYRCTED IY THE WET\AND WATION, PEkfORll4ANCt STANDAAD tS SATISFIED IF THERE IS NO CHANG£ TO Will.ANO llMrri. NAnV£Vf6ETATION Vt.AAS l, 2, 3, 4, S, 7 AND 10 TRE[ AND SHU SPEm (OEATED WETIAND/ {TO octUR IN o\UGVST OR • tooi5UIMVAL YINSTAUEDPLANTSTOCK.alTtR TffE mSTGRC7NINGSEASON. ENHANCEO WETLAND-8UfFEA) SE'1TM8£ll lf61NNING ONE . 80K SURVIVAL IY INSTAUED PlANT STOCK AFJEft THE SECOND GaOWING SUSON • YU,R RH.LOWING INfTIAI. • ENHAHCIO IUfFU N.AlfflNG AJI~ MINIMUM MRaNT COVEa lVTJIEESANDSHlUBS: YEAII: 3: P~NT INSTAUATION.) ~; YEM S: 4S"; YE.U 7: 65"; YEM 10: '°'6. u, TO 20% OF TltE NATIVE WOODY PLANT SPlOES COVERAGE MAY BE COMPAIS£D OF DESIRAII.E NA.TM COlONIZING SPECIES. • OIUllOWITI.AND PlNfflNG MEAS; MINIMUM N:IIQ:NT COVEii 8l nus AND SHRU8S: YEA.A!; !fflli; YEARS: li(Mli; YI.U 7: IC*; YiAfl 10: !lmli. UP TO 2°" Of THE NATM WOOOY PLANT SPECIES tOVEAAGe MAY IE COMPAISlD OF OfSIRMlE NA.TM COlONWNG SPEOES. . AFTER THE flfTH ~OwtNG SfASON, A MINfMUM Of FOUR ou=m1ENT PLANT $.PECIES Will COMPfl:ISE GUATfR THAN 109' COYIRAGE. EME1ENTSas • Y"AVI CO\/EkAGE IYINSTAUED PLANT STOO:ARUl;THEAI\ST&ROWIHGSEASON. . ~AVllAGf.CO'it:M<il BYINSTAlLEDNANT STOO:AfTfR lHf.Stb at~ seuons. . SOK AVUAG( COYEltAGl IY NA.TM IMIRGlNT PLANT SPECIESAFTP: THE ING SfASON . • AFRR THl Aflli GROWING SIASON, A MIMMIJM Of lHRIE OJFfl:RtNT Pl.ANT sPECllS WIU. COMPRISEGRIATlR THAN 1°"COVIRA<ii. !UIU l., t, I.•, J, 'I NII~ JO NATIVE VtG£TATION {TO«oMIN.tU:tJCTM . 100%SURVIVAI. SYINSlALLEOPLANTSTOO(AfTHl THE FIRST GR.OWING SEA.SON . lllf'ilMlh~ll,1> .. 'l-..,;:)Nl fRISlORED WETlAND IUFFEII.) ....,. fQu.awui. ""'1'V\s . 80% WRVIVN. IY INSTAlllD P~ STOOt Aflt:R TM~ fHIROGROWING SEASON . tUIII I IN:)IM.J.l ,~l NOXIOUS WEED SPEO£S YEARS 1, 2, !,4, S, 7, ANO 10 LfSSTHAN 10% COVf:IAGI IV ALLCI.ASrA", "I", ANO "C" NOXIOUSWffDS{INO..UDING NON-M'GIAATtD "I" ANO "C" NOXIOUS WEED5,) IDENTIFIIDON THl LATUT llNG COUNTY NOXIOUS WEED UST. NOXIOUS WlfO CX>HTlOL PERJORMANCE STANDARDS ARE UMfrED TO ltlAHTED AREAS ONLY. 7.0 CONTINGENCY PLAN 7.1 A contingency plan can be implemented if necessary. Contingency plans can include re-grading, additional plant installation, erosion control, modifications to hydrology, and plant substitutions including type, size, and location. 7.2 Careful attention to maintenance is essential in ensuring that problems do not arise. Should any of the site fail to meet the success criteria, a contingency plan will be developed and implemented with the City approval. Such plans are prepared on a case- by-case basis to reflect the failed mitigation characteristics. 7.3 Contingency/maintenance activities will include, but are not limited to: -Replacing all plants lost to vandalism, drought, or disease, as necessary. -Replacing any plant species with a 20 percent or greater mortality rate with the same species or similar species approved by the City Biologist. Fieldbrook/# 11-121 Sewall Wetland Consulting, Inc. February 24, 2014 Page 22 -Irrigating the mitigation area only as necessary during dry weather if plants appear to be too dry, with a minimal quantity of water. -Reseeding wetland and buffer areas with an approved grass mixture as necessary if erosion/sedimentation occurs. -Removing all trash or undesirable debris from the wetland and buffer areas as necessary. If you have any questions regarding this report, please call us at (253) 859-0515 or at esewall@sewallwc.com . Sincerely, Sewall Wetland Consulting, Inc. Ed Sewall Senior Wetlands Ecologist PWS #212 ---'1R{®mi~(Q)ID1 (€D Planning Division ~ [p [p [R1 (Q) w [E [g) By ff@. Awrl)w d Date ~e:<54 Th/bee e)J/ /I~ Spring Brook Coal Company The City of Renton ha s a Jon g history of coa] minin g beginning in 18 73 with the di sc overy of the first coa l seam and th e formation of the Renton Mining Company, Jn c. by Erasmus M. Smithers and Captain Willi am Renton. The Hen son Hill area was hom e to th e Spring Brook Coal Company, which indud cd the J\o. 3 coal seam which opened in th e early 1930s. Th e upp er and Jow er splits of the No. 3 coal scam underlay a portion of thi s site. Coal minin g remain ed one the area's mo st important economic indu stri es throughout the 1930s and many oth er small bu sin esses dev eloped to serve th e coal miners and their familie s. With the advent of hydro-el ec tric power, electricity began to replace coal as an energy sour ce an d th e coal minin g indu stry in West ern Washington dwindl ed. The last active mine in the region was closed in 1974. As you walk throu gh th e wetl and s on this site, yo u will still see remnants of the coal mining operation throughout th e land sca pe, indudin g the ]arg e coa l tailing s pil e locat ed lo th e south . Cl 111.enton Hi,tory Muteum, All ri,ghts resenoed. Photos Courtesy of th e Renton Hi stori cal Soc iety --Fl A.-V A.N'A. ~TRAl LS City or Renton Pla1111inq f1ivision FE8 2 ti 20\~ ~~~~~W~[Q) ~ -::::. -..;;:;::_ ® (g "° §l § nnn §)--~ r.=. ') 'U) ~ ;~ >~ :[; 0 (Q) L°'21 r-T\ ~ -, ._., n C . Q C fry c L::!.=i ru QJ ro 'Cr .L.> -l:=.=:l >-,o o..~ coo FEB 2 6 2014 SIDE 1 ,, . ' j ~ ,')--,_ ·-. ---,.......,. '<--.. .· ·.:,· "?}< .. ' .. <·· •. ~· Pacific W i llow (Sa lix Lasi andr a) Sa l monberry (Rubus Spect ab ili s) Mallar d Duck (Male) Vegetation and Wildlife of the A vana Trails ., .:,,···-~··. .. . ·-.. r"'1 . ~ ~!1.-.J •• ~\~ ~~ :.·-~~'f:V.''r-~~-:."'°':;~~~ -~ ',.._· -> ~--·-~ . • ,.,~ .: .. 1 :::::.~~~: .. -.·; _,, ' -... .,,..,.; .... -~ .r-· I _;;~(:: ·.:.;~-:-'°l~~~~~. ~- ~,; ! \\ ;_;.:. :-~· ~ ;;f :<~ ' -'.~~ ~-.A: .. "<-' ~ ,, ~- ~. -~--:,._ --~~~-.. , . ·"!I<..' ~ ~\f..A" •. ,, ,.. ··. ' . . " ···-• :...&. Sitka Spruce (Picea Sitchensis) Black Twinberry (Lo nice r a lnvolucra) Great Bl ue He r o n Wetland Creation and Restoration Project . ~- , . .• ~-·-; __ ., '1k . . s ~ ;.t'V._ .·· ·-·--~--. '. ~-6,. Western Cr abapple (Malux Fusca ) Indi an Pl u m (Oe m leria Ce r as ifor m is) - Ameri can W i geon Oregon Ash (Fraxin us Latifoli a) Slou gh Sedge (Carex Obnupta) Beaver Sitka W illow (Sa lix Sit che n sis) Sp ike Rus h (El eocaris Parvula) • ~ • ·~- ~ a .·. ~ !'i · •. ... 1,j ~'.~{:\> . -·~·"-_.··· /· / ,w,··; _,. . : .t.-·: ;--"'l ;- • • • .. :--..,.. \. ,1): A e -. Red-l egged Fr og Re d-osier Dogwood (Cornus Stolonifera) Sma ll Fruited Bu l rush (Sc i rpus M i crocarpu s) Muskrat SIDE 2