How Many Houses Could Be Built Realistically? 63 to 97
Features of the Tritt Property
Isakson Living has asserted in their zoning application that 209 single family houses could be built on the Tritt property (see page 34). 209 houses would not be possible given the present zoning R-20 code, and it would also be highly unlikely given the features of the property and the surrounding neighborhoods. The maximum number of houses that could be built with the current R-20 zoning is 80 homes, and rezoning it to R-15 could result in as much as 97 homes. Attempting to rezone any portion of the Tritt property to anything other than R-15 would be met with opposition.
The Tritt property has 7.5 acres of floodplain mostly along Sewell Mill Creek, which forms the western boundary of the property. Cobb County does not allow buildings to be constructed in any floodplain. The Tritt property is 53.7 acres total, but only 46.2 acres are outside the floodplain. This is important because floodplain must be subtracted from total acreage before calculating the number of dwelling units (houses) per acre.
Streams and Stream Buffers
The property is bounded by Sewell Mill Creek on the west and has two small unnamed tributary streams that flow across the property into Sewell Mill Creek.
Sewell Mill Creek - the property has approximately 1,600 feet of frontage on the creek. Sewell Mill Creek is considered a major creek (it flows into Sope Creek, which then flows into the Chattahoochee River), and has 100-foot stream buffers on either side that cannot be cleared or developed. Most of the 100-foot stream buffer lies within the floodplain, but in a few places it extends beyond the floodplain.
Small Streams - The Cobb County GIS map hydrology layer shows approximately 4,130 ft of smaller streams on the property, consisting of two small unnamed tributary streams and their branches. Those which are state waters will get 50-foot stream buffers on either side that cannot be cleared, and an additional 25-foot buffer on either side that can be cleared, but cannot be significantly graded or have any impervious surfaces (e.g., buildings or pavement). Roads can be built across the stream, but they must be more-or-less perpendicular to the stream and no more than 50 feet wide. If the County determines that all of the streams on the property are state waters, that would mean about 8 acres of stream buffers, not counting the stream buffers that overlap the floodplain.
We have laws that protect floodplain and stream buffers for environmental reasons - they naturally filter pollutants - as well as for flood control. The Tritt property drains other properties, especially to the south and east, and, by law, must continue to do so. In 2009, major flooding affected East Cobb Park, the Tritt property, and the surrounding neighborhoods, which is why it is essential that any development not exacerbate flooding issues. Also, law requires that the property not contribute any more water or less water to Sewell Mill Creek than it currently does.
The property has several permanent easements.
Steep Slopes - As noted in the Cobb County zoning analysis, the property has steep slopes approaching 30% on the northeast and southwest corners. A 30% slope is steep - professional cyclists had to walk their bikes up a 27% slope in Italy. The steep slopes on the southwest corner are quite visible from Fullers Park if you go to the baseball field at the rear of the park and look into the woods. Much of the hilly topography can be graded or blasted flat, but that is more difficult to do near the property lines, when the neighbors are uphill, particularly in fairly narrow areas between stream buffers and the property line. Certainly, houses could be built in these steep areas, but not built to high densities, because trees will be required for erosion control, and because driveways may require switchbacks to climb the slope.
Applicable Zonings for the Tritt Property
A developer can ask for a property to be rezoned to any zoning code in Cobb County, but unless the code is one recommended for the land's future land use category, the rezoning is unlikely to be accepted. The Tritt property is Low Density Residential (LDR) on the Future Land Use Plan, meaning up to 2.5 houses per acre. The acceptable zonings for LDR land are: CCRC, RR, R-80, R-40, R-30, R-20, R-15, RA-5, OSC. Many of the zonings are less dense than the Tritt property's current R-20 zoning, and so won't be considered.
Note the commercial and office zonings are not acceptable on LDR land, and Isakson Living assertions that commercial or office buildings could be built on the Tritt property are simply scare tactics (see page 34). Zonings are approved by elected county commissioners, and there would be far too much uproar about any commercial or office development on the Tritt land. And, the commissioners would have the county's guidelines and zoning codes on their side in denying such a rezoning request.
Each zoning has a multiplier which is used to determine the maximum number of houses that fit on certain acreage, with room for streets and right of way, and still have enough room for minimum lot sizes.
*RA-5 is limited to only 20 acres
We can dispatch RA-5 first. Besides being limited by code to only 20 acres, it is simply unacceptable on the Tritt property. None of the surrounding or nearby developments have a density anywhere near 5 units per acre, and the vast majority of the adjacent and nearby developments are either zoned R-20 or R-15. Density is a major factor in residential rezoning cases, and commissioners are very reluctant to allow new developments with density far greater than adjoining developments. The developers of the Mabry Manor subdivision, which is currently under construction on the corner of Holly Springs Road and Post Oak Tritt Road, asked for 20 of the 33.5 acres to be zoned RA-5, and the rest R-15, but the Board of Commissioners would only approve the entire development at R-15 with 1.9 units per acre. The East Cobb community would strongly oppose any RA-5 proposal on any portion of the Tritt property.
That leaves the current zoning of R-20 and R-15. It is very likely that there will be significant opposition to ANY rezoning of the Tritt property, so it may remain R-20. Or, it may be rezoned to R-15. As stated above, the Tritt property is 53.7 acres, but 7.5 acres are in the floodplain and cannot be used for density calculation. Only 46.2 acres are outside the floodplain. Not including the other encumbrances on the property (stream buffers, easements, steep slopes) that would limit the number of homes in a subdivision, we arrive at these numbers:
Nearly one-third of the Tritt property may be impossible to build on due to floodplains and stream buffers, and a few more acres may be impractical to build one due to steep slopes, or very narrow strips of land between buffers and the property line. Certainly floodplain and stream buffers can be part of the back yards, but houses, driveways, and all other impervious surfaces must be out of the floodplain and stream buffers. The amount of stream buffers may very well mean that even fewer houses can be built.
These numbers are far less than the 209 houses claimed by Isakson Living. In fact, no zoning exists for Low Density Residential land that would allow 209 houses on the Tritt property without an extreme variance by the Cobb Board of Commissioners. We feel the Tritt property is large enough that no variances should be required, and we would strongly oppose any variances that would increase density.
Open Space Community
OSC, or Open Space Community, is another zoning possibility for the Tritt property. OSC is considered an "overlay" over other zonings, such as R-20 and R-15. OSC can be a good fit for a property with many encumbrances to development - floodplain, stream buffers, steep slopes, etc. It allows the developer to build slightly more dense by preserving more land as open space.
For R-15, OSC allows up to 2.25 houses per acre if at least 33% of the property is preserved as open space. For the Tritt property, that would mean at least 17.7 acres preserved, and at most 80 houses.
For R-20, OSC allows up to 1.92 houses per acre if at least 38.5% of the property is preserved as open space. For the Tritt property, that would mean at least 20.7 acres preserved, and at most 63 houses.