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HomeMy WebLinkAboutrevised narrativeNotice of Intent Richard and Ellen Mello, 140 Blue Rock Road, South Yarmouth Page 1 of 6 Performance Standards Narrative, Alternatives Analysis, and Construction Protocol - revised Property Description The property is located on the Bass River; a tidal river on Nantucket sound. The property is located in “The Narrows”, a narrow section of river where the current is swifter than most other parts of the river. The project site is approximately 3.6 miles inland from Nantucket Sound. The property is located on the western shore of the Bass River. There is no salt marsh fronting the property. The site has a very tall and steep coastal bank, with existing access stairs and a dock that were permitted and reconstructed in 2016-2017. All of that work was performed by the owner. The existing dwelling was reconstructed in 1975 (assessors records). While there is a small high tide beach on this property, the tidal current is taking sand away, filling in the channel, and causing increased erosion at the base of the bank slope. Erosion has increased with the opening of the new bike path bridge, and increase current along this stretch of the river. There is now a very sharp, vertical drop at the base of the bank, which continues to increase. The bank slope is completely wooded, well vegetated and stable, with combinations of small and sparse understory growth, ivy, and small and mature trees. There are 167 trees on this site, with the majority along the coastal bank. The trees are shading out much of the understory growth. Many trees are covered in vines, many are leaning towards the water. The driveway is paved, with a pervious parking area on the south side of the lot. That area is fairly level. There are also many trees in this area as well. Approximately 37 trees are proposed to be removed on the coastal bank to provide additional light for understory growth. Another 23 trees are in the buffer zone, and are also proposed to be removed to provide access for construction and a proposed garage. Refer to the project plans for specific elevations and details, and enclosed construction protocols. Project Description – Proposed Work The purpose of the project is to obtain an order of conditions to install a short vinyl sheetpile bulkhead along the base of the bank slope, manage the bank vegetation with a combination of tree pruning, de -vining, and removals, and construct a garage where the existing parking area is now. Each phase is described separately below. Bulkhead: The purpose of the bulkhead is to halt the erosion of the base of the bank and provide shorefront protection along the bank bottom. The bulkhead is proposed to be installed above MHW, and angle in a few places to follow the bank slope along the shoreline. The bulkhead will provide erosion protection to keep the bank stabilized, and allow the understory to develop undisturbed. Access for the bulkhead installation will be entirely from the upland. There will be an access path/road cut down on the south side of the property, in an existing “swale”. This will allow a small excavator to gain access to the slope above the bank bottom to drive the sheeting. A section of the existing stairway will be removed temporarily to provide access on the north side of the stairs. The returns for the bulkhead will extend landward until the top of the bulkhead meets the existing grade. Once completed, the area will be backfilled. Fiber rolls are proposed on the north and south ends of the bulkhead to provide a transition zone for current and wave energy. Once the work is complete, the access will be regraded and restored to match pre-construction conditions. The bulkhead installation is proposed to be accomplished by the property owner. There have been many conversations regarding how the work will be performed, what tools and equipment will be used, etc. There is a well thought out plan for this work. Please consider that the owner reconstructed the stairs and the landings and dock by himself. He is more than capable of doing this work, and understands that he is completely responsible for the outcome. The quality of work on the stairs, landing and dock is the same or better than professional marine contractors have done, and should speak for itself . The bulkhead location is staked and located along the bank slope by the property owner. Tree Work: As previously stated, there are 167 trees on this site. There are 60 trees proposed for removal. The remaining trees will be de-vined and dead-wooded as needed to improve the condition of the tree. There are 37 trees proposed for removal on the coastal bank, approximately 22 proposed for removal along the buffer zone, construction access, and the proposed garage. Notice of Intent Richard and Ellen Mello, 140 Blue Rock Road, South Yarmouth Page 2 of 6 There are 3-4 trees at the very base of the bank slope that will require complete removal to allow for the bulkhead installation. These trees are right on the edge of the top of the scarped slope, are leaning over towards the water, with half or more of the root system exposed. They will not survive. Those 3-4 trees are proposed for complete removal to allow the bulkhead sheeting to be installed as close to the scarped slope as possible. There is one tree proposed for removal on the north side of the lot, in the front yard buffer zone. This tree is a hazard to the dwelling. All trees will be flush cut and removed from the site. Some of the cut trees will be used temporarily to stabilize the access path/road down the bank slope, but will be removed at the completion of construction. All of the trees have been identified and marked by the property owner. An arborist is proposed to accomplish the tree work. While the trees are flush cut, a crane will be used to lift them up from the bank and then loaded for disposal. Some trees can be winched up the slope as well, depending on their location. All trees will be removed to the front yard for disposal; no trees are proposed to be removed from the water. The access route will be located to go between as many of the existing trees as possible, especially along the south slope from the existing driveway. Proposed Garage; The garage is proposed to be in nearly the same location as the existing parking area along the south side of the driveway. Stakes are in place to show the proposed location. This area was staked by the surveyor. The garage is located in a previously disturbed area, with other structures and hardscape seaward of its proposed location. Access for this project will be entirely from the upland. Another similar bulkhead was constructed to the south of this property from a working barge. That barge used a vertical tripod/crane system to install the sheeting because it could get very close to the base of the bank slope, and the crane could lean far enough to get over the sheeting. The water is deeper there, the river slightly wider, and the site had very little, if any, high tide beach. Therefore, a barge had just enough room to drive the sheeting from the water. This is not the case for this site. A barge can’t get close enough to the bank bottom (even at high tide) to use the crane/tripod equipment. By the time you get a barge large enough to float an excavator large enough to drive the sheeting, that type of barge will require 4-5 feet of water, which is not available close enough to the bank bottom (because of the existing beach). In addition, the barge would take up too much room, where the waterway is the narrowest along this stretch of river. Construction sequencing: The tree work is the first work needing to be accomplished. After the trees are pruned, de-vined and removed, the access can be created and some of the cut trees can be used in areas where needed to provide stabilization of the access over and along the bank slope. The second portion of the construction would be the bulkhead. Lastly, after the bank slope and access have been restored, the garage can be constructed last. Resource Area Determination The project site is located on Bass River, a tidal river which flows to and from Nantucket Sound. Mean High Water and Mean Low Water elevations can be obtained from the Army Corps Profiles, (Tidal Profile #9), and indicate the elevations in NGVD which exist at the mouth of the river. The further you travel upstream, the more impact the river bottom, land restrictions, etc. impact the flow of water and reduce tidal flow, limiting the tidal elevations. There is a stamped plan of record for this project that indicates MHW and MLW from historical data from previous projects along this portion of the river. Navigation The location of the proposed bulkhead is landward of the MHW mark, as close to the bank bottom as possible. Since the project will be conducted from the upland, there will be no impact to navigation along the waterway. Alternatives Analysis for the Riverfront Area (Discussion of Options) The project as proposed protects the coastal bank from erosion and the introduction of unwanted sediments into an area of the river that is shallow with a swift current. The project also manages the vegetation on the bank to improve light and promote understory growth. As such, the following analysis is offered to describe the available options for this project. Notice of Intent Richard and Ellen Mello, 140 Blue Rock Road, South Yarmouth Page 3 of 6 Option 1- Do nothing If nothing is done at this site, the bank will continue to erode, releasing sediment into the river and impacting available water depths. The swift current may carry some of the sediment away, where it could negatively impact other areas of the river upstream and/or downstream. The waterway is narrow and shallow, which is why the current is so strong here. There are portions of the river directly upstream and downstream of this site where there is less than 2-3 feet of water at low tide available for navigation in the channel itself. While the bank slope is currently vegetated and stable, erosion at the base will eventually cause the start of “slippage” a condition that works its way up the bank, causes large amounts of material to enter the waterway at once, and leaves the bank unstable and unvegetated. Eventually, as we have all seen, the erosion works its way to the house, threatening the stability of the foundation itself. This is a condition that should be avoided, and the applicant is being accordingly proactive. The south side of the dwelling already has been anchored due to its close proximity to the top of the coastal bank. Therefore, the Do Nothing option is not a viable option. OPTION 2: Construct the bulkhead from the water. As previously discussed, this option would be very difficult, requiring specialized equipment, if it can be done at all from the water. In addition, the barge would likely cause an impact to navigation because it would have to be anchored in water deep enough at low tide to avoid grounding. The work, if even possible, would only be able to be performed at high tide, severely limiting daily construction time and extending the overall construction period (and associated impacts) greatly. Even if possible, this option does appear to be the best option based on impacts to the surrounding area, and therefore is not the desired option. OPTION 3: Construct the bulkhead using a crane. This option was looked at for the property to the south (172 Blue Rock Road). The properties are similar. The horizontal distance from the bulkhead location to either the middle of the front yard (for access to the north side of the bulkhead), or from the driveway (for the south portion of the bulkhead) is approximately 125. The weight of a vibratory hammer spanned that distance requires a large crane; one that is not available from at least two of the marine contractors in the area. Swinging that large of a crane over or through the existing trees in the front yard, and over the trees in the back yard poses excessive difficulties, even if a crane large enough is available. The added expense of a crane while not a conservation concern, is obviously a concern the for homeowner. Therefore, utilizing a crane to install the bulkhead sheeting does not appear to be a viable option, and therefore, this option was not chosen. OPTION 4: Utilize fiber rolls or other “soft solution” along the entire bank bottom instead of the bulkhead. This option was never considered viable for several reasons. First, there is, in fact, a soft solution about one quarter mile downstream of the applicant’s property (184 Blue Rock Road) that has a fiber roll installation to stabilize the bottom of the coastal bank there. That installation is right at the “mouth” of the “narrows”, where the current is much, much slower than the tidal current in the narrows. It is also south of a timber bulkhead that extends further seaward than the property with the fiber rolls. The northern end of the fiber rolls was destroyed relatively quickly over time, having been installed around 2016. The southern end of the installation does require some maintenance at this point. The Narrows is an area of high velocity; much more than what exists at the 184 Blue Rock property, where the property is sheltered in a much wider area of the river and off to one side. The applicant’s property is directly in the narrows, where the river is at its narrowest point. The current is swift during the tidal runs, exceeding 6 knots (as measured from my boat). In addition, boats transiting upcurrent at higher tides will produce a wake that reaches the bottom of the bank. The point is that the applicant’s site will see much, much higher wave energy than the site at 184 Blue Rock Road. And if that solution didn’t fair well over 6-7 years, it certainly won’t fair well at all at 140 Blue Rock Road. It would be a waste of time and money to install a soft solution in such a high velocity area. Further consideration should be given to the fact that when these types of installations fail, the bank can fail more, and the beach and bank have to be disturbed again; either for maintenance or reconstruction. Equipment is needed on the beach for this type of installation. For the proposed project the bulkhead can be constructed from the upland, with no equipment on the beach. In this way the beach is not disturbed during the installation of the bulkhead; which is more desirable for the environment that repeated disturbances for maintenance and reconstruction of a soft solution. There is no way a soft solution will work in this location, and that is why this option was never considered viable for this location. Notice of Intent Richard and Ellen Mello, 140 Blue Rock Road, South Yarmouth Page 4 of 6 OPTION 5: Install a rock revetment at this location. The installation of a rock revetment at this location was also not considered a viable option because a revetment would take up too much area on the beach, and require deep excavation into the beach in a area of high currents. Even at low tide, there is not enough soil above the low tide line to allow excavation deep enough to install toe stones. All of the beach would have to be excavated, and there would be no high tide beach once the revetment was installed. In addition, the logistics of getting the rocks to this location, in a barge small enough to transit under either of the two bridges, with a barge large enough to hold an excavator, is simply not feasible at this location. For this and many reasons, a rock revetment was not considered a viable option for this site. OPTION 6: Project as proposed – This option provides the benefit of performing all the work from the applicant’s property, with no impact to navigation, the river itself, and surrounding areas. While the project appears large in nature, each portion of the project is quite manageable. The homeowner has developed a detailed plan to accomplish the bulkhead installation from his own property. The stair and dock work are first rate, and the owner is confident that the work can be done without significant or permanent impacts to the property. The bulkhead will protect the coastal bank from erosion (pre-1978 dwelling) and the introduction of unwanted sediments into the river. The tree work will improve the condition of the existing trees, increase light on the east facing coastal bank, allowing more understory growth. Overall, the project will enhance the resource areas without significant or permanent impacts. The new bulkhead and fill will restore the coastal bank, and stabilize the bottom of the bank slope, preventing any slippage and protecting the existing vegetation above. For these reasons, this option is the preferred option. Performance Standards The project proposes the construction of a proposed vinyl bulkhead, tree management and removal, and a proposed garage. The areas affected by the project include Coastal Bank, Coastal Beach, and the Riverfront Area. Each resource area is addressed below separately. The project as proposed will not have any significant or permanent adverse effects to the surrounding resource areas. Coastal Bank - The area of work over the coastal bank extends along the entire bank for the tree work, and along the bottom of the bank for the bulkhead work. The project will be conditioned to prevent negative impacts to the bank. No negative impacts are anticipated. In fact, the bank will be improved because of the restoration and stabilization. Under the Yarmouth Wetlands bylaw, section 2.05(3)a-2, there is no other method of protecting the bank and the dwelling other than a proposed coastal engineered structure. This is because soft solution will not work in this location due to high current velocities and boat wakes. Please refer to Option 4 above for soft solutions as discussed for this location. Further, this is an area that is silting in from coastal bank erosion, and now requires dredging to maintain sufficient depths for boat passage. Continued silting in from erosion will occur if a soft solution fails at this location. Therefore, only a coastal engineered structural solution should be used in this location. The project as proposed will stabilize the bank and prevent further siltation into the channel. While the eroding bank provides some sediment to the downdrift beaches, (a negative impact in this area), it is the opinion of Shorefront Consulting that this introduction of sediment is not significant (significant is not quantified in the regulations) at this time. If the bank erodes to a point where “slippage” starts to occur, then large amounts of sediment would be introduced into the river, which would be undesirable. Therefore, the project as proposed can be permitted under 310 CMR 10.30 (6) through (8), and the Yarmouth Wetlands bylaw, section 2.05(3)a-2. Coastal Beach - The area of coastal beach extends along the site. While the sheeting will be installed at the very landward area of coastal beach, no equipment will be on the beach itself. Any work to install the anchors and wale and cap can be done either from the land or by hand standing on the beach. The construction will not change the role for the beach in storm damage prevention, flood control, or protection of wildlife habitat. The bulkhead and associated construction effort will also not change the volume or form of the beach sediments. The configuration will also not change the ability of the beach (seaward of the bulkhead) to respond to wave action, or the effect for any downdrift beach. The bulkhead and work to install it, as designed will have no adverse impacts to the coastal beach, and therefore meets the performance standards for work on a Coastal Beach. Therefore, the project as proposed can be permitted under 310 CMR 10.27 (1) through (7). Notice of Intent Richard and Ellen Mello, 140 Blue Rock Road, South Yarmouth Page 5 of 6 Riverfront Area - There is both 100-foot and 200-foot riverfront area buffer zones on this property. The work in the 0-100 riverfront area is limited to the tree work. There is some tree work and the garage work that is within the 100-200 riverfront area. None of this work will impact the riverfront area itself. Full restoration of the access path will keep the bank riverfront area stable and well vegetated. Please refer to the discussion of project alternative stated previously in this narrative. CONSTRUCTION PROTOCOL The staging area for materials will be on the applicant’s property. The work area shall be kept to a minimum. All equipment shall be stored on the applicant’s property when not in use. No heavy equipment is required or allowed on the beach. Any refuse material shall be removed from the coastal bank daily. The trees shall be removed by crane or winch as necessary, and removed from the site. The access shall be restored to pre-construction conditions as much as practical. Refer to the restoration protocol below, which should be included in the order of conditions. Pre-Construction Meeting Prior to construction, a pre-construction meeting shall be held on-site with the Contractor, Property Owner (or owner’s representative), and the Conservation Commission and/or agent. The purpose of the meeting is to clearly delineate the limits of work and access, as well as the staging area. The Contractor will describe the proposed means and methods for performing the work within the requirements of the plans, order of conditions and construction protocol. The Contractor will comply with mitigation measures as established by the Conservation Commission. All disturbed vegetated areas shall be re-vegetated with similar native vegetation to match pre-construction conditions and the surrounding areas, or as determined during the pre-construction meeting To be discussed at this meeting: • Existing property conditions, necessary precautions to be taken by the Contractor; • Means and methods for construction; • Means and methods for siltation controls; • Necessary post-construction reparations and conditions; • Procedure for post-construction inspection; • Shorefront Consulting’s responsibilities for inspection and project coordination During Construction, the site shall be accessible for inspection during reasonable hours by all parties, members of the conservation commission and their agents, and the Project Manager. Post-construction meeting Upon completion of construction, but prior to equipment being removed from the site, a post-construction meeting shall be held on-site with the Contractor, Property Owner (or owner’s representative), and the Conservation Commission and/or agent. The purpose of this meeting is to determine that the project has been satisfactorily completed in accordance with all permits, and that no additional work or mitigation is required by the Contractor. Restoration of project area Upon completion of construction, the staging areas, vegetated areas, and any other areas disturbed by the construction effort shall be returned as much as practical to their pre-construction conditions to the satisfaction of the property owner and conservation agent. Suggested Conditions for project – (suggested to be included in the order of conditions) Restorative plantings shall be installed immediately in any areas left bare from the construction effort. This includes temporary stabilization with natural turf reinforcement matting, and native plantings that match the surrounding vegetation. It is not possible to assess an accurate amount of total restorative plantings at this point in the project. One of the anticipated outcomes is a naturally developed and increased understory vegetation along the entire coastal bank, which would provide the desired outcome naturally. The area of the path must be restored, and the commission may require partial mitigation on the bank for a period after construction. Notice of Intent Richard and Ellen Mello, 140 Blue Rock Road, South Yarmouth Page 6 of 6 Normally, a simple calculation would be provided to plant a definitive number of plants in specified areas or for a total amount of square feet of plantings. However, as the tree work will improve available sunlight to improve natural understory development, it is unknown at this time how the bank will respond to the increased light. Therefore, it is suggested that the bank slope be evaluated for 2 growing seasons after the construction of the bulkhead and the access restoration. The garage work is not considered in the timeline for completion of the work for mitigation on the bank. The areas can be evaluated to see if the project areas have restored themselves to a satisfactory condition. While “satisfactory” is subject to interpretation, it would seem that any further mitigation work would be obvious, or just minor in nature. If the bank area has not fully restored itself to a satisfactory condition, then it is recommended to require a 2:1 mitigation planting of native shrubs or small trees in the areas that have not appreciably restored to satisfactory condition. This would amount to up to 74 plants, shrubs, or small trees, planted in various areas, and this quantity can be adjusted as needed to compensate for established areas, potentially reducing this quantity. The resulting evaluation can be performed by a certified arborist or contractor qualified for this type of work (not necessarily a CERP). Since the bank is stable and not barren of vegetation, that level of expertise is not required for this project and only serves to increase the cost unnecessarily. The conservation commission should also visit the site and determine if any further corrective action is needed to restore the area. Once a determination is made, the appropriate mitigation would take place. This may require the extension of the conservation permit to allow this work to be completed and accepted by the c ommission. This process is suggested to allow the bank to restore itself naturally at first, and then augment the plantings as needed after a period of time. This seems to be a practical approach to let nature do what it does first, and then provide additional help as needed. The project can not be closed out until the bank is restored to a satisfactory condition; whether mother nature does it naturally, or additional work is required to obtain the desired outcome.