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Home My WebLink About03019 - Technical Information Report - Wetland Mitigation Report {__� , ' � , MAUREEN HIGHLANDS — Renton, Washington WETLAND MITIGATION REPORT , ; � , , Prepared For: Wilshire Investments, LLC Bellevue, Washington Prepared By: TALASAEA CONSULTANTS, LLC Woodinville, Washington C,�Y OF RENTON �ECEIVEC �� 2 � 1�0� 20 February 2002 ti,u51'OM6tt SEFi v��:E 3oi 9 � ' MAUREEN HIGHLANDS - Renton, Washington WETLAND MITIGATION REPORT Prepared for: li ' Wilshire Investments, LLC 1285— 140th Place NE Bellevue, WA 98007 Preparec : Talasaea Consultants, �� 15020 Bear Creek Rd. N.E I 20 February 2002 Maureen Highlands Wetland Mitigation Report EXECUTIVE SUMMARY THIS REPORT: This report replaces Sections VI through XIII of Talasaea's Sensitive Areas and Mitigation Report dated 10 May 2001, submitted to the City of Renton in May 2001. Detailed information about existing site conditions for the Maureen Highlands project may be found in the earlier report. SENSITIVE AREAS: In September 2000, Talasaea Consultants identified and delineated the on-site wetlands. For more detailed descriptions of each wetland delineated on the property, please refer to the Sensrtive Areas and Mifigation Report prepared by Talasaea Consultants, dated 10 May 2001. Talasaea Consultants delineated four wetlands (Wetlands A, B, C, and D) totaling 63,537 square feet (sf) on the project site. King County conducted a site visit in the fall of 2000 and verified the wetland boundaries. PROJECT IMPACTS: Wilshire Investments, LLC has proposed a residential development consisting of 124 single-family lots located on the 36.85-acre site in the City of Renton, ' Washington. The development infrastructure includes a system of asphalt-paved roads, cul-de-sacs, driveways, and two stormwater detention facilities. The proposed action involves clearing and grading of approximately 35.1-acres and impacting 10,875 sf of on- site wetlands. Impacts to Category III wetlands will occur as fill and "unbuffered" wetlands. The project proposes to fill 7,391 sf of Wetland B. The project will also impact 3,484 sf of wetlands (831 sf of Wetland B, 1,976 sf of Wetland C, and 677 sf of Wetland D) by providing buffers with less than the standard widths. Total impacts to Category III wetlands are 10,875 sf. Wetland A (2,729 sf), a small isolated wetland under 5,000 sf, will be filled as part of the proposed development. IMPACT MITIGATION: Mitigation for the 10,875 sf of impacts to Category III wetlands will occur as 10,875 sf of wetland creation and 12,746 sf of wetland enhancement (1:1 creation and 1.2:1 enhancement ratio). A 25-foot enhanced buffer will be provided. 20 February 2002 Talasaea Consultants, LLC 572B-Mit-Rpt(20Feb02).doc Page i Submittal Maureen Hiahlands Wetland Mitigation Reoort TABLE OF CONTENTS Page i. Executive Summary ii. Table of Contents iii. List of Figures II. List of Drawings iv. List of Tables 1.0 INTRODUCTION---------------�------------------------------------------------------ ---------------------------� 2.0 GENERAL PROPERTY DESCRIPTION AND LAND USE______________________________________1 2.1 Wetland Classifications 1 ---------------------------------------- -------------------- -------------------------- 3.0 DEVELOPMENT IMPACTS 2 --------------------------------------------------------------- --------------------- ---- 3.1 Project Description___________________ ___________2 ---------------------------------------------------------------- 3.2 Impacts to Sensitive Areas----------------------------------------------�----------------------------------3 4.0 MITIGATION FOR IMPACTS 4 4.1 Goals and Objectives----------------------------------------------------------------------------------------5 4.2 Hydrological Support and Grading___________________________ ___6 --------------------------------------- 4.3 Plantings------------------------------------------------------------------ -- ----7 - -----------------------------------�- 4.4 Habitat Features 7 ------------------------------------------------------------------------------------------------- 4.5 Irrigation.---�---------------------------------------------------------------------------- ------$ ------------------------ 5.0 CONSTRUCTION MANAGEMENT----------------------------------------------------------------------------$ 5.1 Post-Construction Assessment 8 ------------------------------------------ ------- .---------------- 6.0 MONITORING PROGRAM_____________________ _._____8 ----------------------------------------------------- -------- 6.1 Vegetation-----------------------------------------------------------------------------------------------------------9 6.2 Wildlife 9 ----------------------------------------------------------------------------------- - ------------------------------ 6.3 Hydrology, Water Quality, and Site Stability________________.______________________._________9 7.0 SUCCESS CRITERIA FOR PLANT ESTABUSHMENT 10 I� I' ---------------- ------------------------ � 8.0 MAINTENANCE (M) AND CONTINGENCY (C)______________________________________________________10 9.0 PERFORMANCE BOND 11 10.0 AS-BUILT PLAN 11 � - - - - - - - -- - - ----- -- - - - --- - 20 February 2002 Talasaea Consultants, LL 5726-Mit-Rpt(20Feb02).doc Page ii Submit� I Maureen Hiahlands Wetland Mitiaation Reoort I LIST OF FIGURES Figure 1. Location Map Figure 2. Proposed Site Plan and Wetland Impacts LIST OF DRAWINGS index of Drawings (enclosed j Sheet 9-0: Overview Plan Sheet 9-1: Grading Plan and Details Sheet 9-2: Grading Specifications Sheet 9-3: Planting Plans and Plant Schedule Sheet 9-4: Planting Details Sheet 9-5: Planting Specifications 20 February 2002 Talasaea Consultants, LLC 572B-Mit-Rpt(20Feb02).doc Page iii Submittal Maureen Hiahlands Wetland Mitiaation Reoort_ __ LIST OF TABLES Table 1: Wetland Regulatory Conditions Table 2. Summary of Wetland Impacts Table 3: Projected Calendar for Performance Monitoring and Maintenance Events 20 February 2002 Talasaea Consultants, LLC 572B-Mit-Rpt(20Feb02).doc Page iv Submittal �4aureen Highlands Wetland Mitiqation Re�ort 1.0 INTRODUCTION This wetland mitigation plan has been prepared to describe the wetland impacts and proposed mitigation for the Maureen Highlands project (Figure 1) located in the City of Renton, Washington. This mitigation plan is designed to meet the requirements for projects impacting wetlands and wetland buffers, as stated in Section 4-3-050 of the City of Renton's Environmental Regulations. This report replaces Sections VI through XIII of Talasaea's I Sensitive Areas and Mitigation Report dated 10 May 2001, submitted to the City of ' Renton in May 2001. Under the proposed residential subdivision project, 7,391 square feet (sf) of wetland would be filled and 3,484 sf of wetland would be impacted by buffers with less than the standard widths. Information presented in this report will be utilized by the Renton Planning Department to assist in their evaluation of impacts from the proposed project on sensitive areas. I 2.0 GENERAL PROPERTY DESCRIPTION AND LAND USE ' The subject property is located on the north side of N.E. 4`h Street, east of Rosario Avenue N.E. in Renton, Washington (Figure 1). The property is located in the southwestern quarter of Section 11, Township 23 North, and Range 5 East, W.M. The property is a rectangular-shaped parcel approximately 36.85-acres in size. The topography is relatively flat with a gentile slope to the eastern edge of the property. The southwestern corner drains a relatively small portion of the property to a stormwater collection system at N.E. 4th Street. Four wetlands (Wetlands A, B, C, and D) totaling 63,537 square feet (sf) on the project site were delineated in September 2000. Currently, the property is farmed as a hay crop. A horse is pastured in a small area southwest of the residence near N.E. 4th Street. Except for this residence and several fruit trees, the property is undeveloped. 2.1 Wetland Classifications . In September 2000, Talasaea Consultants delineated four wetlands (Wetlands A, B, C, and D) totaling 63,537 square feet (sf)on the project site. For more detailed descriptions of each wetland delineated on the property, please refer to the Sensitive Areas and Mitigation Report prepared by Talasaea Consultants, dated 10 May 2001. Wetland A (2,729 sf) is an isolated topographic depression, smaller than 5,000 sf in size and is exempt from regulatory status under Section 4-3-050(B)7(a). See Table 1 for regulatory conditions. Wetlands B, C, and D would be classified as Category III wetlands by the City's Code, and would require a 25-foot buffer(Table 1). Table 1. Wetland Re ulato Conditions Wetland Wetland Type Buffer Wetland A 2,729 sf exempt none Wetland B 31,963 sf Cate or III 25-feet I� Wetland C 11,618 sf Cate or III 25-feet Wetland D 17,227 sf Cate ory III 25-feet 20February 2002 Talasaea Consultants, LLC 5726-Mit-Rpt(20Feb02).doc Page 1 Submittal Q _ C!' � - s — ----- -t--- SE —� --- --- � --A R `� '< � �en+ �<' , � �� /�i� �c�$� � � S7 SE, , 108T}� ST �' �Q�� __ ._ � .. �� c+,p� I J`F. \ 8N 1jlpnj ST i :�t �� COALF D s � �° � T� � `;�:� s: ��z�, sT IS , '`�^ �` € ~se �ii3n, „ issa� ( S,qQ!! �. 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North DESISN DRA�1N PRG_EGT TALASAEA FIGURE I: L� ��2 Sa:PLE CONSULTANTS, LLC Locatfon Map T Resou-ce E Er��ro�me��ta� ��a�� Maureen Highlands °P'� I ��:�eek Ro�N��theast Renton, Washington 10-30- hbodirt.�il�e,r�ashlnaton 990-2 REVIS�D Bis(425!P.61-"I�Sv-�az(425�90�_'�>q _� _ �C Cop�^iaht - Talasaea Gors„Ca-�ts ��:iaureen Hicl��lands '�^�'ef�and P:1 haaticn Repert 3.0 DEVELOPMENT IMPACTS 3.1 Project Description Wilshire Investments, LLC has proposed a residential development consisting of 124 single- family lots located on the 36.85-acre site in the City of Renton, Washington (see Figure 2 and Sheet 9-0, enclosed). The development infrastructure includes a system of asphalt-paved roads, cul-de-sacs, driveways, and two stormwater detention ponds. The proposed action involves clearing and grading of approximately 35.1-acres and impacting 1G,875 sf of on-site wetlands. 3.2 Impacts to Sensitive Areas Impacts to Category III wetlands will occur as fill and "unbuffered" wetlands (Figure 2). Direct fill to Wetland B will result in an impact of 7,391 sf. Site development will result in a "paper fill" (unbuffered wetland) of 831 sf of Wetland B, 1,976 sf of Wetland C, and 6�� of Wetland D by not providing the required buffer width. Total impacts to Category II I wetlands are 10,875 sf. The "unbuffered° wetland areas will not be physically impactF the development; however. mitigation �vill occur as if they were filled Wetland impacts ��re summarized in Table 2. The standard bufferwidth Tor Gategory III �vetlands is 25 feet. The project wiil p�cvide �r enhanced 25-foot buffer for the remaining portions of Wetlands B, C, and D. Wetland A (2,729 sf) is a small isolated wetland under 5,000 sf and is not regulated u the Crty of Renfon's En��ironmental Reacalations Wetland A will be filled as part of rhF proposed developmen Table 2. Summar of .. _..�. ,. .. ,r: ._, , - -- -_ - — - = -- -__— _- Wetland Wetland Type Fill Unbuffered Wetland Wetland A 2,729 sf exem t 2,729 sf'` none Wetland B 31,963 sf Cate or III 7,391 sf 831 sf Wetland C 11,618 sf Cate or II I None 1,976 sf Wetland D 17,227 sf Cate o III None 677 sf TOTAL IMPACTS 7,391 sf 3,484 sf * Wetland A is not regulated and, therefore, is not included in the total for filled wetland. 4.0 MITIGATION FOR IMPACTS Mitigation for impacts from the proposed project will occur on site through a combination of wetland creation and enhancement, and buffer enhancement (see Sheets 9-0 through 9-5, enclosed). Two mitigation areas are described in this report. Their locations are depicted on Sheet 9-0. Mitigation Area 1, located in the central eastern portion of the site, consists of wetland creation and enhancement for impacts to Wetlands B, C, and D and buffer enhancement (see Sheets 9-1 and 9-3). Mitigation Area 2, located in the central portion of the site on the western property line, consists of wetland and buffer enhancement for impacts to Wetland D (see Sheet 9-3). • � Mitiqation Area 1 Mitigation Area 1 represents mitigation for the 10,875 sf of impact to Category III wetlands (Wetlands B, C, and D). Mitigation will occur in the central eastern portion of the site as both 20February 2002 Talasaea Consultants, LLC 5726-Mit-Rpt(20Feb02).doc Page 2 Submittal � _—_ -1�.. o b. " � ---j��-'1�--jl—jj'-'lt''_-`_I I- , �-—;� �--!�___��_--��,___�� ; ! PL�N LEC�ND i i 7th GT. ---� ''---- - - PROPERTY L I NE �---' — — �' — WETLAND BOUND/�RY � ,�W�TL�rND^ �i ^i1 � i i �'_____ — — WETLAND BUFFER �---� i�-��n___��_ �___,� � ,__� �--, � i--i i � i 2,�2G sf-,---, -. i �---� U ii i' i� � .r� I� � ;--- i i �� L—��_�i__��_—% �i �=_� i � �___� N NE 7th P r� i r--- �---� � ��_� �__, —,�'��\��' � IMP�GTS L�C�ND - 10.8�5 sf �---, o I� � i � �� i_ _�� ..d i__! �_=!I ��;�/ � FILLED WETL,4ND��91 sf� (1^ETLAND A 15 EXEMPT UNDER GI RENiON ) ` � r i � � � �� C : � UNBUFFERED WETLP�ND (3 484 sf) �---� Z I__-' �-_-I .•_•. . .•.:... � �-- A�u�ren_ar+o wi�ee Ew+ewc.ev�,s eu�x1 �---� �-1•� �--i i--� � , i I � ��°�r�= ------- �___;� V IETL�N � a =_===�;::.. '�_ � ,� �; �� __=_===-_ �---� --------=::: =-------...: �---I i:31,G63 sf, -_-_--_-�::� i_-- i '� � �\ '`�_�'`:::::::�::>:; �___,I �� `, , � � .,; � W�TL,a,ND MITIC�TIOI� LEC�ND i� JI �---, ,`---� � ;_ �__ � � � � :��:�-- �:�:;:�� PRESERVED WETLAND (3q,a02 sf) i � � -� � �%'`� '�' �• !� GRE/�TED WETLAND �I�'IS sf �` �,��_, ��' � F::.�:.�:�;::':;;:`-::::.�.a (i,i�nct�r+r-ro-wss rsnrio r-oiz i arv wenaw��) �-----� ,- -, ��WETL��ID. ::.::: � �--- -- �===� ENHANGED WETLf�ND (12,746 sf) \ �\ \,�II�II`��i' �� - i fi��ieav��nrw,no) �---� \��I1,618 sf,�� ' � �� ENH�NGED BUFFER WETL,4ND � ` � -' �' , �_ � �__=� ��D�� - _ --- 17,2�7 sf �:�:=:��.� L__� �,. �__� , : � i----- .',• � % 9 I :� �=� - / �� '� � �� ;-_. o � ,----, �`"� STORMWJ�TER � ; I �— i r�/ /� \ ' _ `� � POND A < ', i --_'__� `�� I - � . i � r �1 �jj �, � i i (i�— NE bth 5T L__; i i I1,i �_li__ir__i , r-- i I � � '. I__� �_ _I I� � ; � �I �� ..._i J�� --- r--� � I � I .� � i �I �_=i �-�:i� NE �th GT. � i I'� _ �==i �i i i i �, �_, i �I �=� �-_� li \\ii�^�ii`` � `--� i � i � i �i i i i ,�--- /� r--� I � I � �l___��__�I---� N � I 0 I__ I I__ II 'I fl r--II N Ij �� j � �---��--��--� ii_ 7 i fl I � I � �I I I � � � ----- I � �--� �--�� D �__i o i--' i--i I`J�. ,�,i,,,� '�' -_ r-- i � �--i� � �i= _ _ , Maureen Hi�hlands Wetland Mitiaation Reoort wetland creation of 10,875 sf(1:1 replacement-to-loss ratio) and wetland enhancement of 12,617 sf (1.2:1 replacement-to-loss ratio). Section 4-3-050 (M)(12) of the City of Renton's Envrronmenfal Regulations allows enhancement of an existing wetland in conjunction with creation of a wetland as mitigation. The code allows for a 1:1 replacement-to-loss ratio for wetland creation and a 1:1 replacement-to-loss ratio for wetland enhancement. Both wetland creation and enhancement will result in a qreater than 2:1 replacement-to-loss ratio. Wetland creation will occur between Wetlands B and C, and portions of Wetlands B and C will be enhanced with minor grading and planting to create a larger, more diverse wetland ecosystem. The "unbuffered" portions of Wetlands B and C will also be enhanced with native plantings. In addition to the wetland mitigation, the required 25-foot buffer for the Wetland B/C system will be enhanced through minor grading to create berms, which will provide increased protection to the wetland system. The buffer will be planted with native evergreen and deciduous trees and shrubs to provide additional protection to the wetland system and to increase habitat for wildlife. Mitigation Area 2 Mitigation Area 2 represents buffer enhancement for impacts to Wetland D (see Sheet 9-3. The buffer will be pfanted with native evergreen and deciduous trees and shrubs to provide additional protection to the wetland system and to increase habitat for wildlife. Additional plantings within the area of the stormwater ponds could also promote increased habitat value (see Landscape Plan). 4.1 Goal and Objectives Goa! 1: Replace the wetland functions and values lost due to filling of 7.391 sf of wetlands, and replace and improve wetland functions and values of 3,484 sf of wetlands affected by buffers with less than standard widths. Objectives: � • Create 10,875 sf of Category III wetland adjacent to Wetlands B and C and enhance 14,617 sf of these wetlands to increase functional values of the wetland system (replacement-to-loss ratio of greater than 2:1). • Excavate ponds to various depths to increase diversity of aquatic and wetland habitat. • Augment wetland hydrology in existing wetlands with collected rooftop runoff released through infiltration trenches. • Incorporate snags, down logs, stumps, and brush and boulder piles for enhanced wildlife habitat. • Construct cavities in selected stumps and down logs for critters and plantings to ; enhance wildlife habitat. � • Install bird nesting boxes on snags. • Plant a variety of sizes and species of evergreen and deciduous trees and shrubs to create structural diversity and habitat improvement. • Plant a wide variety of emergent species, interspersed with seasonal open water, for amphibian enhanced habitat. 20February 2002 Talasaea Consultants, LLC 572B-Mit-Rpt(20Feb02).doc Page 3 Submittal f.•au�e�i I-i�l��isn�� i�ellard '�-'i'gati��n Reccrt Goal 2: Provide wetland and water quality protection, and increase wetland functions, through buffer enhancement. Objectives: • Construct earthen berms in the buffer areas to provide screening of the sensitive areas, both visual and physical. • Plant the buffer areas with evergreen species to provide visual barriers, and augment with species that have thorns, dense habits of growth, etc. to provide physical barriers. • Increase the wetland buffer plant species diversity and structure in the same manner as in the wetland, and incorporate snags, down logs and stumps to enhance wildlife habitat value. • Incorporate informational signage to increase awareness and appreciation of the adjacent wetland ecosystems. . 4.2 Hydrological Support and Grading Development of the northern portion of the site will result in an increase in surface runoff due to impervious surfaces. Wetland B will correspondingly receive less surface and shallow groundwater flows. To augment hydrology to Wetland B and the mitigation wetland � area, clean rooftop runoff from homes adjacent to the wetland will be routed to an infiltration trench that will slowly release water into the soil at the outer edge of the wetland (see Sheet , 9-1). Shallow groundwater flows from the infiltration trench will supply needed hydrological support to Wetland B and the mitigation wetlands. The enhanced and created wetland areas will be graded to create a series of shallow ponds that will step down in elevation to provide a shallow, open-water component to the wetland system. A rip-rap spillway will be constructed at the exit from the mitigation wetland areas to maintain desired water elevations in the created wetland pond. Water will exit the mitigation area into an existing ditch located on the eastern property line. Upon completion of grading in the created wetland areas, a geotechnical engineer will review sub-grade material to determine whether a bentonite clay liner will be required to prevent or retard water infiltration through the pond bottoms. 4.3 Plantings The plant species used in the mitigation plan (Sheet 9-3) were selected for a variety of qualities, including adaptation to specific water regimes, value to wildlife, value as a physical or visual barrier, pattern of growth (structural diversity), and aesthetic values. Native tree, shrub, and herbaceous species were chosen to increase both the structura� and species diversity of the wetland and buffer areas, thereby increasing the area's value to wildlife for food and cover. Species of vegetation that are both beneficial to wildlife and unfriendly to humans will be used in areas where human exclusion is desired. Plant materials will consist of a combination of bare-root specimens, container plants, and cuttings. 4.4 Habitat Features Snags, down logs, stumps, brush piles, and boulder piles (if excavated from site development) will be incorporated into the mitigation wetland and buffer areas to provide ecologically important habitat features for wildlife. 20February 2002 Talasaea Consultants, LLC 572B-Mit-Rpt(20Feb02j.doc Page 4 Submittal Ntaureen Highlands Wetland Mitiaation Reeort Snags provide perching, feeding, and nesting sites for a variety of native birds. Cavity nesting bird species, such as tree swallows, violet-green swallows, chickadees, and woodpeckers would be expected to utilize such features. A bird-nesting box will be attached to each installed snag to initiaily augment the natural habitat. Down logs and stumps provide the slow release of nutrients as the wood decays, and also provide cover for amphibians, small mammals, and other wildlife. Selected down logs and stumps will have cavities constructed in them to provide habitat for critters and plantings. Brush piles will also be placed throughout the mitigation areas to provide important cover for various birds and small mammals. Boulders recovered from site excavation will be placed in small piles at selected locations within the mitigation areas. These piles provide potential habitat for reptiles and small mammals. 4.5 Irrigation A temporary above-ground irrigation system will be designed and installed by the landscape contractor for the mitigation areas. This irrigation system will be depicted on the as-built drawing. To minimize the potential.for plant desiccation in the mitigation areas, a soil moisture retention agent will be incorporated into the backfill of planting pits, as required, based on site conditions. 5.0 CONSTRUCTION MANAGEMENT A pre-construction meeting will be held on site to review and discuss all aspects of the mitigation project prior to any construction activity. The owner, as well as a City representative, will attend the meeting. Prior to commencement of any work by contractors in the mitigation area, the clearing limits will be staked and fenced. Silt fences will be installed at the clearing limits adjacent to sensitive areas at locations, depicted on Sheet 9- 1, and significant habitat features and vegetation to be retained will be clearly marked in the field. Areas will be designated for stockpiling of topsoil and habitat features. A wetland biologist or landscape architect will regularly supervise plan implementation during construction to ensure that the objectives and specifications of the mitigation plan are met. Any significant modifications to the design that may occur as a result of unforeseen circumstances will ba a�nr�,,�� h,; +ho �,;,,,,or +hP �'�+;, �n�± Ta�a��P� r�n��!ta�ts nri�r r,,, their implementatior 5.1 Post-Construction Assessment A post-construction assessment will be �ui��iu�i�ia u�ui i ��c i,�iCuvi i u� i�ie in�uyaiivi i Ni��i construction, and a report, including an as-built drawing, will be submitted to the City. Tr purpose of this assessment will be to determine whether the site conditions are consiste� with the approved plan and to establish baseline conditions for future monitoring. 6.0 MONITORING PROGRAM Performance monitoring of the mitigation areas will be conducted for a period of five years, with reports submitted annually to the City of Renton according to the schedule presented in Table 3. 20February 2002 Talasaea Consultants, LLC 572B-Mit-Rpt(20Feb02).doc Page 5 Submittal Maureen Hiahlands Wetland Mitigation Reoort TABLE 3: Pro'ected Calendar for Performance Monitorin and Maintenance Events Year 1 Year 2 Baseline Assessment PM-2 PM-3 PM-4 MR PM-5 PM-1, R, MR MR MR R, MR R, MR Winter 2003 S rin 2003 Summer 2003 Fall 2003 S rin 2004 Fall 2004 Year 3 Year 4 Year 5 MR PM-6 MR PM-7 MR PM-8* R, MR R, MR R, MR S rin 2005 Fa112005 S rin 2006 Fa112006 S rin 2007 Fa112007 "Obtain final approval to get release of bond from City of Renton (presumes performance criteria are met}. PM = Performance Monitoring R= Report MR= Maintenance Memo and Review Each monitoring report will include: a) photo-documentation, b) estimates of percent vegetative cover, plant survival and undesirable species, c) wildlife usage, d) water quality and hydrology, site stability, and soils, and e) an overall qualitative assessment of project success for the wetland and buffer areas. The first monitoring report will serve as the baseline assessment report. If the performance criteria are met, annual monitoring will cease after the fifth year, unless objectives are met at an earlier date and the City accepts the mitigation project as successfully completed. 6.1 Vegetation Permanent vegetation sampling plots or transects will be established at selected locations within the mitigation area to incorporate all of the representative plant communities. The � same monito�ing points will be re-visited each year, with a record kept of all plant species found. Vegetation will be recorded on the basis of relative percent cover of the dominant species within the vegetative strata. All monitoring will be conducted by a qualified ecologist from Talasaea. Locations will be established wifhin the mitigation area from which photographs will be taken throughout the monitoring period. These photographs will document general appearance and relative changes within the plant community. Review of the photos over time will provide a semi-quantitative representation of success of the planting plan. Vegetation sampling plot and photo-point locations will be submitted with the baseline assessment report. 6.2 Wildlife Birds, mammals, reptiles, amphibians, and invertebrates observed in the wetland and buffer areas (either by direct or direct means)will be identified and recorded during scheduled monitoring events, and at any other times observations are made. Direct observations include actual sightings, while indirect observations include tracks, scat, nests, burrows, song, or other indicative signs. The kinds and locations of the habitat with greatest use by each species will be noted, as will any breeding or nesting activities. 6.3 Hydrology, Water Quality, and Site Stability During each monitoring event, an assessment will be made of the water regime within the mitigation area to ensure that proper hydrological conditions exist within both the wetland and its buffer. General observations will be made of the extent and depth of soil saturation or inundation. 20February 2002 Talasaea Consultants,LLC 572B-Mit-Rpt(20Feb02).doc Page 6 Submittal Maureen Highlands Wetland Mitiaation Reoort Water quality will be assessed qualitatively, unless it is evident there is a serious problem. In such an event, water samples will be taken and analyzed in a laboratory for suspected pollutants. Results will be reported quantitatively. Qualitative assessments of water quality include: • oil sheen or other surface films, • abnormal color of water or odor, I� • stressed or dead vegetation or aquatic fauna, � • turbidity. Observations and evaluations will be made of slope and soil stability in the mitigation areas. Any erosion or slumping of the soils will be recorded and reported so that corrective measures may be taken. 7.0 SUCCESS CRITERIA FOR PLANT ESTABLISHMENT Success of plant establishment within the mitigation areas will be evaluated on the basis of both percent survival and percent cover of desirable species. For woody planted species, success will be based on at least an 85% survival rate of all planted trees and shrubs, or at least 80% cover of equivalent re-colonized native species by the end of the five-year monitoring period. Success for herbaceous species will be based on an 80% cover of desirable plant species by the end of the five-year monitoring period. Undesirable plant species will be maintained at levels below 20% total cover. Removal of these species will occur immediately following the monitoring event in which they surpass the 20°/a maximum coverage. Removal will occur by hand whenever possible. No chemical treatment will be employed without prior approval from the City. Undesirable species include S�,ot's broom, Himalayan and evergreen blackberry, reed canaryg�as�, purple loosestrife, hedge bindweed (morning glory), Japanese knotweed, and�reeping nightshade. 8.0 MAINTENANCE (M) AND CONTINGENCY (C) Maintenance will be performed twice per year to address any conditions that could jeopardize the success of the mitigation areas. Established performance standards for the project will be compared to the monitoring results to judge the success of the mitigation project. If there is a significant problem with achieving the performance standards, the bondholder shall work with the City to develop a contingency plan. Contingency plans may include, but are not limited to: re-grading, additional plant installation, erosion control, modifications to hydrology, and plant substitutions of type, size, quantity, and location. Contingency will include many of the items listed below and would be implemented if these performance standards are not met. Maintenance and remedial action on the site will be implemented immediately upon completion of the monitoring event (unless otherwise specifically indicated below). • During year one, replace all dead plant material. (M) • Water all plantings at a rate of 1" of water at least every week between June 15 — September 15 during the first year after installation, and for the first year after any replacement plantings. (C & M) • Replace dead plants with the same species or a substitute species that meets the goal and objectives of the mitigation plan, subject to Talasaea and agency approval. (C) • Re-plant area after reason for failure has been identified (e.g., moisture regime, poor plant stock, disease, shade/sun conditions, wildlife damage, etc.). (C) 20February 2002 Talasaea Consultants, LLC 5726-Mit-Rpt(20Feb02).doc Page 7 Submittal I i_ Maureen Hiahlands Wetland Mitiaation Re�ort • Remove/control weedy or exotic invasive plants (e.g., Scot's broom, reed canarygrass, Himalayan blackberry, purple loosestrife, etc.) by manual or chemical means approved i by the City. Use of herbicides or pesticides within the mitigation area would only be implemented if other measures failed or were considered unlikely to be successful, and would require prior agency approval. Trees and shrubs should be weeded to the dripline and mulched to a depth of three inches. All non-native vegetation must be removed and dumped off site. (C & M) • Clean-up trash and other debris. (M) • Selectively prune woody plants to meet the mitigation plan's goals and objectives (e.g., thinning and removal of dead or diseased portions of trees/shrubs). (M) � Repair or replace damaged structures, including fences, signs, and bird boxes. (M) • Make minor excavations by hand, as needed and after consulting with City staff, to correct surface drainage or soils moisture conditions. (C) • Line uvetland areas with impermeable material where hydrology is deemed to be insufficient 'to support the desired wetland plant community(ies). Where appropriate, liners may be installed in the wetland mitigation areas at time of initial construction to increase success probability. (C). 9.0 PERFORMANCE BOND A performance bond will be posted with the City of Renton by the property owner for the cost of plant replacement plus five years of performance monitoring. The bond may be released either in whole or in partial amounts, at the sole discretion of the City. Partial release of bonding obligation would be in proportion to work successfully completed over t'r�e five-year m�nitoring period. 10.0 AS-BUILT PLAN Followir�g cortzpietion of construction activities, as-built plans for the wefiand mitigation area will be provided to fhe City of Renton. The plans will identify and describe any agency- approved changes in grading, planting, or other constructed features in relation to the original approved plan. i I 20February 2002 Talasaea Consultants, LLC 572B-Mit-Rpt(20Feb02).doc Page 8 Submittal