Nancy & Clay: I have provided some notes below regarding the subject lot drainage problem. Your feedback may help us better define the scope of work in our drainage proposal. The attachments are intended to help illustrate the notes. While working for EH&A over ten years ago, I was retained by the Town to design a stamped concrete flume to alleviate a lot drainage problem on the adjacent lot to the north (Lot 7). As part of this design, I verified that the 6” mountable street curb upstream of this lot (Bellbrook Drive) had sufficient capacity to convey the flow in the street. Consequently, Lot 6 should only be receiving runoff from the lot(s) upstream of it (Lots 10 & 11), not from the street. Since then, a gate has been constructed across the top of the flume with a wire mesh underneath to keep the owner of Lot 7’s dog in. It’s possible that the wire mesh collects debris which could reduce the flume capacity; however, the flume was designed conservatively and the Lot 7 owner didn’t mention having any problems with it. Also, the Lot 11 owner has constructed a bag wall next to the flume that appears to redirect the runoff from a portion of his driveway towards the southwest corner of Lot 7. However, it’s not apparent without further inspection that any of this redirected runoff reaches Lot 6. Currently, a railroad tie retaining wall in poor condition generally runs along the rear of Lot 6 and supports the improvements in the rear yards of Lots 10 and 11. A smaller, lower railroad tie wall berm is located parallel to it. A rear yard swale is located between these two walls with a high point in the general vicinity of the common line between Lots 10 and 11. Some debris is evident in the swale which appears to be relatively flat. The rear yard swale transitions at the north (Lot 7) end to a 20+ long section that drains through openings in the railroad ties towards Winnwood Road. Based on Chris’s recent site visit with Clay, the following appear to be two potential solutions. These solutions are intended to avoid construction that might be construed as impacting the condition of the retaining walls. However, the scope of either solution could be expanded if the Town were willing to replace the lower railroad tie retaining wall berm with a flume. 1. Construct a swale along the north side lot line of Lot 7 that collects runoff from the existing rear yard swale and conveys it to Winnwood Road. - The property owner reported that a previously functioning side yard swale had been silting up over time and was blocked when they installed a landscape bed. - A portion of the landscape bed would need to be removed and some minor work would be required to the downstream end of rear yard swale. - This solution is the most straightforward if it is acceptable to the property owner. - The Town may consider giving the property owner input regarding the swale surface; for example, grass, stamped concrete, or some other material. - However, if the Town constructs the swale, we’d recommend that some agreement be reached with the property owner regarding maintenance. - Perhaps a drainage easement would be sufficient to prevent the Town from being liable should the swale be blocked in the future. - NOTE: This solution assumes that the flow in the rear yard swale does not leak through the lower railroad tie wall. We’d want to check for evidence of this on site and by asking the property owner. 2. Extend the existing stamped concrete flume about 20’ on to the subject lot to collect runoff from the existing rear yard swale. - Field survey grades would be needed on the concrete flume and the rear yard Lot 6 swale to determine if this solution is feasible. - Some modifications to the existing concrete flume on Lot 7 would be needed. - Due to the jog in the rear property lines of Lots 6 and 7, a new drainage easement will be required from the Lot 7 owner for the flume modifications. - The capacity of the flume and its outfall will need to be checked. - A grate would need to be installed across the flume where it crosses under the fence between Lots 6 and 7 to keep the dog in. - Some minor ponding may still occur on Lot 6 between the concrete flume and the landscape bed unless this area can be regraded to the rear. We’d be pleased to meet with you at your office or on site if these notes prompt further questions. Regards, Bruce