ADDENDUM #1 RFP WOLFTRAP CREEK STREAM RESTORATION

Transcription

1 ADDENDUM #1 February 6, 2015 RFP WOLFTRAP CREEK STREAM RESTORATION ******ATTENTION BIDDERS****** (To be completed and returned with bid response) A request was made that the Stormwater Local Assistance (SLAF) grant package and the supporting documentation be made available to interested firms. Those documents are attached to this Addendum. ALL OTHER TERMS, CONDITIONS, AND SPECIFICATIONS SHALL REMAIN THE SAME. A copy of this signed addendum must accompany your response as an acknowledgment of its receipt: NAME AND ADDRESS OF FIRM: PHONE #: NAME OF AUTHORIZED REPRESENTATIVE: Please Print SIGNATURE: DATE: Page 1

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6 Wolftrap Creek/Difficult Run - Stream Restoration Grant Application Stormwater Local Assistance Fund 2014 Town of Vienna Grant Application for a Stream Restoration Project to the 2014 Stormwater Local Assistance Fund

7 Contents A: Background... 2 B: Environmental Benefit... 4 C: Statement of Need... 5 Condition of the Stream Sections... 5 TP (Total Phosphorus)... 6 Stream Restoration Description... 7 Maintenance... 7 D: Grant Application Summary... 8 I. POLLUTION REDUCTION... 8 II. COST EFFECTIVENESS... 8 III. IMPAIRED WATER BODIES... 8 IV. FISCAL STRESS... 8 V. READINESS TO PROCEED... 9 VI. PHASE II (SMALL) MS E: Closing... 9 Figure 1 Location Map and Extents of Proposed Project... 4 Figure 2 - Section ' eroded bank... 5 Figure 3 - Stream Condition Types... 5 Figure 4 Sinuosity Example... 5 Figure 5 Difficult Run Channel Evolution Model Map... 5 Figure 6 Difficult Run Sub Watershed Modeling Results... 6 Page 1 of 13

8 A: Background: The Town of Vienna is located approximately 15 miles west of Washington D.C. and is called home by approximately 16,000 residents. With a geographic area of slightly over 4 square miles the Town is one of a handful of incorporated areas within Fairfax County. The Town was primarily developed during the 1950s and 60s without the environmental benefits of Stormwater Management and Water Quality Treatment. Further subdivision development in the 1980 s throughout the Town of Vienna increased impervious areas, enclosed tributaries, straightened streams, removed riparian buffers and steepened stream banks to allow more homes to be built. Recently the Town has experienced a redevelopment boom leading to a further increase in impervious surfaces and a further burden on the receiving water courses. Predictably the receiving streams and channels have experienced incision, erosion and widening in response to the increase in water quantity as a result of 50 plus years of development. Within Vienna s four plus square miles is the watershed for the Wolftrap Creek section of the Difficult Run watershed and subject of this application. The Wolftrap Creek section this proposed project will impact is an unassessed portion categorized as a 3A in the Virginia 2012 Impaired Waters 303(d) category list. However other assessed section are listed as type 5 (the most severe impairments). Additionally the Wolftrap Creek flows to the Potomac and the Potomac is under a TDML. Still, this section shares many of the same issues of assessed sections. Additionally, this section is just upstream of a previous restoration project on Wolftrap. The issues affecting this section are the same as the downstream section previous restored, the previously restored section is described as follows from a Fairfax SlideShare presentation: Before restoration, the stream and the natural habitat were degraded. Poor water quality and loss of the natural habitat are hallmarks of a poor environment Uncontrolled stormwater runoff flowed through the stream and eroded the banks exposing tree roots. Trees were falling which created a safety hazard. Sediment was deposited in the streambed by stormwater runoff. Some aquatic animals raise their young in streambeds. Sediment covers the streambed and kills aquatic animals living there. Undercut stream banks, unbalanced sediment transport and fallen trees, demonstrate the before appearance of the area. (County, 2013) 1 Municipal maintenance funds are only available for occasional dredging of sediment but not for corrective action to prevent the erosion and to naturally stabilize the stream. Stream bank armoring and dredging have been used for years as the standard repair method by Vienna stream maintenance crews. Funding is tight; therefore, problems are not addressed preventatively, but only in reactive mode. This project will show local staff and residents the practical aspects of correcting the problem of stream bank erosion before sediment must be dredged from the stream. As it ages, the stabilization of the problem area will demonstrate how carefully preparing for natural restoration is cheaper in the long run with the elimination of costly dredging. This project will extend closer to the ultimate headwaters and additional 1 From :Wolftrap Stream Restoration in Wildwood Park, Vienna, Virginia, slideshow Page 2 of 13

9 action on this stream will help maintain the previously restored downstream section by reducing the sediment load. In 2013 additional regulation in response to the continuing challenges faced by the Chesapeake Bay went into effect and the Town of Vienna, as a MS4 permitee, will experience additional requirements relating to the water quality in its streams. The town has executed a cooperative agreement with Fairfax County to share responsibility for implementing a joint Chesapeake Bay TDML Action Plan. As a function of these requirements and the cooperative agreement with the Fairfax County the amount of Phosphorus, Nitrogen and Total Suspended Solids will need to be reduced. Vienna, in conjunction with working with the Fairfax County, has a role and responsibility in meeting these requirements. Formal correspondence with Fairfax County has indicated available construction funding for the restoration to constitute the matching funds required for the grant, (Appendix C, Letter from Fairfax County). This application also makes multiple references to Fairfax s Difficult Run Watershed Management Plan. This plan describes the needs and requirements for the future of the watershed, and a path to meeting the requirements of the coming regulations. Page 3 of 13

10 B: Environmental Benefit The primary aim and quantified requirement in meeting the grant application standards is establishing the amount of Total Prosperous to be removed as a result of the proposed project. This project proposes to stabilize approximately 1,020 feet of stream bank within the borders of the town of Vienna, see figure 1. The section for restoration is in the Wolftrap Creek in the Difficult Run watershed just upstream from a previously restored section of stream. This section is located entirely on Town property and is close to the headwater of the stream. As a result of being situated in the headwaters, all downstream sections will benefit from stabilization and restoration that takes place in the upper reaches. The erosion of stream banks causes suspended solids, which may be laden with phosphorus, to be suspended in runoff. Additionally, the restoration of stream banks provides a means of pretreatment for runoff and removal of phosphorus prior to reaching the stream. As outlined in the grant application a credit of lbs per linear foot of restored stream is credited for stream restoration projects. Figure 1 Location Map and Extents of Proposed Project o Approximately 1,020 linear feet of restored Stream: At lbs/ft = lbs of removed Phosphorus Phosphorus amounts were tabulated utilizing the grant application credited rate of lbs/ft, methodology for calculating total phosphorus reduction, Attachment A of the Stormwater Local Assistance Fund grant application. Page 4 of 13

11 C: Statement of Need Condition of the Stream Sections The current condition of the stream sections have been evaluated onsite and photographed as shown to the right, additional photographs are included in Appendix A. In addition to the site visits and photographs taken, the Fairfax County Watershed Plan for the Difficult Run was reviewed for insight into the phosphorus loads arising from the drainage areas. Figure 2 to the right shows the degree of incision and erosion along the banks. While walking the stream several areas of 3 to 4 high eroded banks are clearly visible. In many of these areas existing trees have been undermined and overturned. Figure 4 to the right shows the degree of sinuosity in the stream, again a common sight along this stream. As the stream turns there is too much volume and velocity for the existing soils resulting in erosion and loss of available water quality storage treatment in fringe flood plains. The condition of the stream appears to be a Type III as described by figure 3 below and indicated in figure 5 of the Fairfax Difficult Run Watershed Management Plan Chapter 2 Watershed Condtion report. Stream Restoration Grant Proposal Figure 2 - Section ' eroded bank Figure 4 Sinuosity Example. Figure 3 - Stream Condition Types Figure 5 Difficult Run Channel Evolution Model Map Page 5 of 13

12 TP (Total Phosphorus) In reviewing the Difficult Run watershed management plan, as produced by Fairfax County, several items reference the condition of the streams in the Wolftrap Creek portion of the watershed. From chapter 2 of the report: Table 2.17 shows results of the hydrologic and water quality modeling, normalized by area, so that the sub watersheds and be compared directly. There is a correlation between the amount of development and the hydrologic results. Old courthouse Spring Branch has the highest level of imperviousness and the highest runoff volume. Snakeden branch, Wolftrap Creek, Colvin Run and Piney Branch also show high runoff volume and high levels of imperviousness. The same five sub watersheds also have the highest peak flows. Old Courthouse Spring Branch also shows up with the highest levels of TSS, TN and TP from runoff. Wolftrap Creek, Colvin Run and Snakenden branch also have high levels of these pollutants. Figure 6 Difficult Run Sub Watershed Modeling Results As seen above in the table and quote the Phosphorus load in the Wolftrap Creek watershed is considered very high. This very high rating for phosphorus further supports the need for stream mitigation. A map of the drainage areas is included in Appendix G. Page 6 of 13

13 The streams condition assessment indicates a significant need for restoration and stabilization. In conjunction with the watershed s plan finding that the Wolftrap Creek is inundated with high levels of total phosphorus and the significant drainage area to these stream sections this project represents a prime opportunity to achieve the Total Phosphorus reduction goal of the SLAF grant. Stream Restoration Description The goal of stream restoration is to return the stream to a stable state in which it; neither significantly erodes or fills with sediment, is connected to its floodplain and has an improved habitat condition. In so doing a connection to the floodplain is created, reducing total phosphorus discharge, as well as preventing further erosion and bound total phosphorus discharge to the stream. For incised urban channels, such as this one, there are several options available depending on the severity of the section and the extent of adjacent land. The most extensive restoration portions may move the stream itself, creating a new channel on a new alignment at the original floodplain elevation. Other sections could involve adjusting the cross-section, reducing bank slopes, or creating a new floodplain bench within an over-widened channel. For portions with restricted availability of adjacent land where there is no room to increase meander width, the restoration design will use grade controls to flatten the slope of the stream and dissipate stream energy. In the small sections where it is infeasible to recreate a natural channel less extensive restoration approaches will be undertaken. Such measures include armoring stream banks with rock or bioengineering materials to prevent further erosion and grading to lay back over-steepened banks to create a more stable cross-section. Maintenance Provisions for the long-term maintenance responsibility of the restored stream, including an inspection and maintenance schedule, will be included in the project. Project documents will indicate the specific maintenance requirements for the project as well as the duration and ongoing requirements and responsibilities. The project falls within public land owned by the Town. Page 7 of 13

14 D: Grant Application Summary I. POLLUTION REDUCTION Points will be based on the calculated reduction of total phosphorous (TP) as a result of the proposed project. The established methodology for calculating the TP reduction is outlined in Attachment A. Approximately 1,020 linear feet of restored Stream: At lbs/ft = lbs of removed Phosphorus The project proposes a total of 1,020 linear feet of stream restoration with a total of lbs of removed Phosphorus. II. COST EFFECTIVENESS Points will be based on the projected cost of the project divided by the calculated amount of TP reduction. Project Cost as included on the Grant Application = $890,000 Total Phosphorus Removed = lbs Cost Effectiveness Ratio = $12,471/lb III. IMPAIRED WATER BODIES Points will be based on the location and impact of the proposed project in relation to priority water bodies in the state.. Note: These categories (a b) are additive. a. Project is directly related to the requirements of the Chesapeake Bay TMDL 60 pts. b. Project is directly related to requirements of a local impaired stream TMDL 40 pts. or Project is directly related to a local impaired stream without a TMDL 20 pts. The project is not directly in a TDML plan, the project does however flow to Difficult Run, which has some TDMLs, and then flows onto the Potomac and the Chesapeake Bay both of which have TDMLs. IV. FISCAL STRESS 50 of the points for county and city applicants will be based on the latest available Commission on Local Government composite fiscal stress index. Town applicants will be assigned the points of the surrounding county. Any applicant with a project serving more than one jurisdiction (such as public service authorities or towns located in two counties) will be assigned a weighted average from the component scores. An additional 25 points will be awarded to applicants that have established a dedicated local funding/revenue mechanism for stormwater capital projects The Town of Vienna has a dedicated local funding/revenue mechanism. The Stormwater Tax is collected via Fairfax County and portions thereof are then passed onto Vienna for use in implementing The Town of Vienna s responsibilities. Page 8 of 13

15 V. READINESS TO PROCEED Because it is important that grant recipients proceed quickly with their proposed projects, applicants that can proceed immediately with their proposed projects, or demonstrate an advanced state of readiness, will be given the highest points under this category. Design has been submitted, reviewed, and approved 40 pts. Design submitted / under review 35 pts. Reasonable assurance design will be completed / submitted within 4 months 30 pts. Project identified in current year Capital Improvement Plan or annual budget 20 pts. Project included in Stormwater or Watershed Management Plan 10 pts. Additional 10 points will be awarded if land necessary for the project has already been acquired. The proposed project is in the beginning stages of coordination. Fairfax County has committed to providing the local matching funds for this project (see letter of commitment from Fairfax County in Appendix C. The project will be administered by the Town. Upon notice of award of the grant, the Town will immediately acquire a design engineer and begin the project. It can be expected that an engineer could be under contract within three months of the notice a grant award. No acquisition of property is required for this project. The land for the project is already owned by the Town of Vienna. VI. PHASE II (SMALL) MS4 Applicants that are regulated under the General Permit for the Discharge of Stormwater from Small Municipal Separate Storm Sewer Systems will receive 25 points. The Town of Vienna is regulated under a General Permit for the Discharge of Stormwater from Small Municipal Separate Storm Sewer systems. E: Closing In closing the Town of Vienna appreciates the opportunity to apply for grant match funds for a critical and sorely needed Stormwater management project that will benefit the State, Fairfax County, the Chesapeake Bay and Town while meeting our MS4 responsibilities. Page 9 of 13

16 Appendix A Additional Site Photographs Stream Restoration Grant Proposal Page 10 of 13

17 Appendix B - Letter from Fairfax County Page 11 of 13

18 Appendix C Project Location Map Page 12 of 13

19 Appendix D Drainage Area Map Map Source: *Edited to reflect new project Page 13 of 13