Photos of Mulberry Knoll
Before Flood
After Flood
10 days after the last rain
More photos
Seacoastonline Flood Map and Practical Tips
Flooding Issues at Proposed 'Scenic Manor' Subdivision:
96 of the proposed 320 lots in this development, 6 portions of the roads, and half of the clubhouse area are within the FEMA 100-year floodplain. Approximately 43 lots are entirely within the floodplain; the other 53 have varying portions within the floodplain.
The largest stormwater management area located by the clubhouse is within the 100-year floodplain. It is located in Zone AE (EL5) where the water level is expected to rise five feet in a 100-year storm. www.fema.gov This stormwater area will be useless in a major flood event because it will already be under flood water.
Homes built in the AE floodplain zone must be built to raise the lowest floor to the base flood elevation. For AE (EL6), this means that homes must be elevated by 6 feet by fill or by raising the building structure. A large portion of the proposed development ~30% of the lots, portions of the roads and part of the clubhouse ~ will need to be raised. This development will require an extremely large amount of fill, even if some of the homes are built on stilts. The current FEMA FIRM maps were revised in March of 2015. How much fill has been placed in the floodplain for homes built since then and how much have the limits of the 100 year floodplain changed???
ORDINANCE NO. 2384, § 115-141.5, A. (1) (a), p.16 https://sussexcountyde.gov/sites/default/files/ordinances/o2384_flood_map_ordinance.FINAL_01-20-15.pdf
This development will cause increased frequency of destructive flooding AND increased land area with destructive flooding. Houses built in floodplain zone (AE) are required to have the buildings elevated. Fill is commonly used for elevation. Filling in the floodplain increases risk of flooding elsewhere by forcing the water to go further inland, expanding the floodplain into new areas. Every truckload of fill will cause the equivalent of a truck load of water to flood into areas beyond the current floodplain.
Areas in Sussex County that were severely impacted during Hurricane Sandy in 2012 and the 1998 Nor'easter include: Milford, Broadkill Beach, Lewes, Dewey Beach, Pot Nets, Long Neck, Oak Orchard, Bethany Beach, South Bethany, and Fenwick Island. It is unjust to increase the flooding risks of existing Sussex County residents by building new homes in the floodplain.
Many factors in a subdivision increase flooding risks: new houses & roads increases impermeable surfaces and removes top soils; the compacted soils around new houses do not percolate (allow water to penetrate); removal of forested areas & their soils greatly reduces the property's ability to absorb water.
Ten acres of identified soil on this property is known as Manahawkin muck with a flooding rating of “frequent”. “Frequent" means that flooding is likely to occur often under normal weather conditions. The chance of flooding is more than 50 percent in any year but is less than 50 percent in all months in any year, as defined by Web Soil Survey. A primary soil of concern is Hurlock (HvA) which is a poorly-drained wetland (hydric) soil that has severe limitations for development and should be avoided.
The property near lots 276 to 282 may lie within the "Limit of Moderate Wave Action". The developer must include the location of that Limit on the site plan. This is important because it is the inland limit of the area expected to receive 1.5-foot or greater breaking waves during a 100 year flood.
Maps:
Floodplain Map:
FEMA 100-year floodplain shown in light blue. The map marker is located at part of the proposed "Scenic Manor' clubhouse. The orange/white line is the "Limit of Moderate Wave Action", the limit of expected 1.5-foot or greater breaking waves. Source: https://maps.dnrec.delaware.gov/FloodPlanning/default.html
Portions of proposed 'Scenic Manor' Subdivision in the Floodplain:
96 lots & 6 portions of the roads lie within the FEMA 100-year floodplain; approx. 43 lots are entirely within the floodplain, 53 lots are partially within the floodplain
Flood Plain Zones, source: www.msc.fema.gov 10005C0334K.tif
Sussex County Online Map - Flood Zones 2018
Head of Tide Wetlands Map
Depth of water table beneath the 'Scenic Manor' site:
The green marker shows location of proposed stormwater management (SWM) pond adjacent to clubhouse. The water table there is just 0-3' below the soil surface; the soil here will have little capacity to absorb water in the SWM ponds.
Links to Articles:
'How can we save Fenwick Island from the rising tides?' Delaware Online, Jul.17, 2020 https://www.delawareonline.com/story/opinion/2020/07/17/how-can-we-save-fenwick-island-rising-tides-opinion/5423843002/?for-guid=71e66544-16ec-11ea-86aa-12a8ccd2370f&utm_source=delawareonline-Daily%20Briefing&utm_medium=email&utm_campaign=daily_briefing&utm_term=list_article_headline
SeaGrant Delaware - Understanding Flood Risk This website shows maps of the flood water depths of various Sussex County towns during a 100-year flood event (Milford, Broadkill Beach, Lewes, Dewey Beach, Pot Nets, Long Neck, Bethany Beach, South Bethany and Fenwick Island. It also has maps of flood water depths during Hurricane Sandy in 2012, and the 1998 Nor'easter. https://www.deseagrant.org/pot-nets-flood-map
'Delaware Towns could see 100 days of Sunny-day Flooding in 2050, says NOAA report', Delaware Public Media, July 19, 2020. This article discusses 'sunny-day flooding', tides which are 1.75 to 2' higher than normal high tide, and gives data about sunny-day flooding in Lewes. https://www.delawarepublic.org/post/delaware-towns-could-see-100-days-sunny-day-flooding-2050-says-noaa-report
'A strong market could be masking sea level rise's impact on Delaware coastal home values' The News Journal, Sep.26, 2018 This article contain sea level rise data for Lewes, which has been measured to be 3.35mm/year. https://www.delawareonline.com/story/news/local/2018/09/26/how-rising-seas-impacting-price-living-along-coast/1424685002/