OOCResponse34-35.docxResponse to Wetlands Order of Conditions (OOC) Item 34.
“Prior to the preconstruction meeting, the applicant shall provide a revised plan to the Commission for review and approval. Such plan shall include the following items, to the extent
practicable.
Additional treatment methods to improve water quality (e.g. deeper sumps, LID techniques, proprietary BMPs, aggressive street sweeping and winter maintenance).
Natural stabilization methods along the slope of the access road.
Revised plans for the outfall area are provided, see digital copy of Plan Sheets: G-1 (General Notes include erosion controls); C-4 (Demolition in Outfall Area, includes tree protection),
C-18A through C-18H (Outfall Construction); and C-20 (Details of Sediment Controls & Tree Protection)
LID techniques. Plan modifications include two retaining walls: (a) soldier pile and lagging retaining wall along south side of Riverside Drive and (b) gravity block retaining wall
along south side of access drive. These retaining walls provide increase slope stabilization and significantly reduce the footprint of the proposed work. Plan modifications also
include enhanced tree protection in the Outfall area by requiring: (a) temporary chain link fence around protected trees and (b) air-spading and selective root pruning for trees in
close proximity to the work.
Street Sweeping and Winter Maintenance. Current practice is street sweeping one (1) time per year. It is anticipated that future street sweeping two (2) times per year will be conducted
in compliance with the City’s MS4 Stormwater Permit. Winter maintenance includes clearing catch basin inlets of snow and ice after storms and snow pile/bank management. Snow pile/bank
management is primarily in response to road safety concerns (e.g. not obstructing driver sight lines, not allowing lane encroachment, not allowing runoff water ponding in the roadway).
Catch basins. Proposed catch basins will have hooded outlets and deep sumps (4-ft sump below the outlet) to retain floatables and sediments, respectively. Deeper sumps are non-standard
and create installation and maintenance concerns. In some cases, a shallow catch basin (without sump) is installed due to utility conflicts. In these cases, the plan details indicate
that the shallow catch basin shall be connected to a deep sump manhole with hooded outlet – providing the same level of sediment and floatables/oil spill protection. Catch basin maintenance
includes removal of sediments from sumps. Typically this is conducted at least once per year and in response to specific events that carry significant sediment into the roadway.
Natural Stabilization Methods. Slope stabilization includes use of fiber mats to stabilize soils on steeper slopes. Additional stabilization will be provided by the DPW proposed tree
planting program (see response to OOC item 35, below).
Proprietary BMPs. Proprietary BMPs are not included in this project. Most proprietary BMPs require a buried structure or a larger above grade structure. Street reconstruction projects
frequently do not have space within the street for proprietary BMPs due to the limited space and the multiple buried utilities. On this project, the only potential location for a proprietary
BMP would be near the outfall location. A proprietary BMP at this site would further encroach upon the wetland buffer zone.
Response to Wetlands Order of Conditions (OOC) Item 35.
35. The applicant shall replace all trees five inch dbh removed as part of the project. Replacement shall be determined by the number of trees removed only, in-kind dbh replacement
is not required. Plantings should be installed within the resource areas on the project parcel to the extent possible, but may be located within the Hinckley Street Outfall Drainage
Area if necessary. Documentation of replacement plantings shall be requested with a request for Certificate of Compliance. Any planting not surviving after three growing seasons
shall be replaced.
Our current count of five inch dbh tree to be removed is 31; includes trees within buffer zone (outfall area) and along Hinckley Street. Tree replacement will be conducted by the DPW
under the guidance of the City Tree Warden after the construction contract work in the outfall area is completed. Tree replacement will include:
Planting 24 red & sugar maple saplings (1” to 2” diameter) in the region of the Outfall.
Additional tree planting will be conducted along Hinckley Street that will include up to 20 tree saplings (1” to 2” diameter). The type of trees will be selected by the Tree Warden
from the list developed by the Public Shade Tree Commission. Tree replacements along Hinckley Street will be in compliance with the Significant Tree Ordinance.
Additional (optional) planting up to 100 red & sugar maple whips (saplings about ¼” inch diameter and 12” to 24“overall length) in the region of the outfall.
In year three after the initial planting, the Tree Warden will review the planting growth and may plant additional trees, if appropriate.
The above tree planting program meets the requirements of the OOC. This plan may be modified by the Tree Warden or City Arborist in response to site conditions (post construction) and
effectiveness of initial plantings.