Description

The surface and subsurface hydrologic systems on the Boyle/Frank property are being changed as a result of this site development project, with the potential to adversely impact offsite conditions. A seasonal drainage channel has been relocated, and impervious surface area from the new building, deck and patio areas has increased. Furthermore, the extensive changes to site grading (>50 CY) include large areas of cut and disruption below the shallow groundwater table that could also potentially change downgradient conditions offsite.
What is the drainage plan for this site? Have designs been submitted to ensure that there will be no adverse offsite impacts? Are surface and subsurface drainage facilities being properly designed and constructed?
A new rain garden is being designed and constructed onsite. How it will capture all of the increased runoff from the increased impervious area, particularly the patio area in the southeast corner of the property? How well is the new rain garden expected function given the extremely shallow groundwater table?
To date, it is clear that temporary erosion and sedimentation control TESC measures have not been improperly installed and maintained. Why were silt fence BMPs allowed to be removed in May when construction activities were not yet complete? Why have unworked soils been allowed to remain uncovered on the site for more than 7 days?
The seasonal conveyance channel on the south end of the property is a distinct hydrologic feature that ties in to adjacent properties both upstream and downstream. This channel outfalls to the roadside ditch along the west side of Sunrise Drive NE and has a contributing drainage area is approximately 4.5 acres, per previous engineering analysis. This hydrologic feature should have been noted as part of the site assessment. As part of the construction of the accessory dwelling unit at the Boyle/Frank property, the seasonal drainage channel has been relocated farther south, the channel grade has been raised, and the slope potentially altered. The relocated channel no longer properly ties in to the downstream conveyance channel on the adjacent property. This channel relocation and failure to control sediment discharge has and will continue to adversely impact offsite site conditions downstream.
A large patio area is being constructed on the southeast corner of the lot. Is this shown on the site plans and was the increase in impervious area from the patio accounted for in the permit process? A sump pump and/or some sort of infiltration system was originally installed within the new patio area footprint. Was this shown on site drainage plans, and properly permitted and installed? Why was it dug up several weeks later, with piping altered and removed? This system was replaced by a large underground tank/cistern – was this change reported to the City? Will this change how water being handled and conveyed offsite?
Several adverse and sustained site impacts to the adjacent downslope property that have been experienced to date as a result of site construction. These offsite impacts have included unwanted accumulation of sediment and standing water, digging of a large hole with a backhoe, and deposition of hay bales and other TESC measures - all which should be contained within the Boyle/Frank property. Additionally, the adjacent downslope property has been subjected to both tree and lawn damage. These deficiencies have not been corrected in a responsive manner. Moving forward, what measures will be taken by Boyle/Frank to ensure that ongoing adverse impacts will not be experienced offsite both during the remainder of the construction process and in the long-term, after construction is complete? If the City could clarify this, it would be greatly appreciated.