Letter to Boerne City Council

Dear Mayor and City Council Members-

It appears that the Southglen developers are looking for more goodies from the City (annexation? utilities?).  Please consider the following before amending or adding to the existing development agreements between the City and Southglen:

COMPLAINTS: There have been 13 TCEQ complaints against Southglen since 2016 and multiple BMP violations.  Southglen is also being investigated at this time for silt runoff and lack of silt barriers during the storm on July 6th (see attached).

DENSITY: Southglen consists of around 400 lots on 107 acres which implies about 4 homes per acre.  But if you subtract out roads and drainage ditches, the number of homes per acre is closer to 5-6.

DETENTION BASINS: There are only two detention ponds – one is much smaller than the other -- with a capacity of just 25.73-acre feet (8.4 Million gallons).  But this is insufficient for a 6-inch rain which can produce more than 20 million gallons of runoff from driveways, roadways, rooftops and slabs.

DRAINAGE STUDIES / IMPERVIOUS COVER: These studies address increases in peak flow, but they do not address increases in the volume of runoff.  While detention moderates peak flow increases, it achieves that goal by releasing water over a longer period of time.  Southglen's impervious cover was around 5% pre-construction (2015) but is now somewhere between 40-60%.  There are NO substantive green spaces in this subdivision.  Lot pads should be considered 100% impervious cover because the fill piles are compacted by heavy construction equipment.  The City's commissioned report by Maestas Engineering in 2018 confirms the negligence of Cude Engineers regarding impervious cover calculations (see attached).  To quote the Maestas report, "we find that the offsite drainage area and impervious cover calculations for Southglen subdivision to be outside of reasonable care."

MERITAGE PULLOUT:  Meritage Homes was originally slated to acquire half of the lots/pads (Phases 6, 9, & 11?) from the developer at Southglen but pulled out in 2018, purportedly after doing a GPR study that revealed multiple subsurface voids on the property.  Ashton Woods replaced Meritage and is currently building out Phase 11.

QUALITY ISSUES: The useful lives of the home at Southglen are about 25 years according to local engineers not involved in this project.  For example, at a nearby comparable subdivision, Boerne Hollow, the roof was just replaced at a home at 111 Lina Lane built in 2015.  It was apparently due to defect or leakage, not hail damage.  And some homes at Boerne Hollow have been selling below assessed value in recent years.

RECHARGE: In 2017, according to two neighbors, a large piece of construction equipment owned by VK Knowlton fell into a subsurface void at the back of Southglen near the location of the lift station.  Once the equipment was removed, the void was backfilled with concrete.  The concrete cap is visible near the lift station.  This recharge feature helped reduce downstream stormwater by routing it to the aquifer.

SLOPE / VELOCITY / VOLUME: Landscape slope, stormwater velocity and stormwater volume have all increased in the past five years at Southglen.  Slope has increased anywhere from 2-7 feet from five drainage points to one which increases velocity and volume. Stormwater velocity through the natural channel on the property was originally around 2 feet per second (ft/s) but now averages more than 4 feet per second.  A 6-inch rain on 107 acres produces over 17 Million gallons of stormwater of which very little is being absorbed by the former clay beds on the property.

The Southglen builders and developers are only interested in maximizing profits which means squeezing as many homes as possible into this subdivision at the lowest cost possible (permissive building codes created this mess).  Like the Surfside (Miami), Florida situation, these buildings will start showing serious “wear and tear” after just twenty years and at that point will shift to renters instead of owners.  HOAs will try their best to stem the degradation but board members won’t have the skills to turn things around.  Crime will increase and property values will fall.  It’s yet another local subdivision “time bomb” in the making.  Hopefully, the new city manager, who I hear lives in one of these “pop up” subdivisions, gets a first hand look at what City government is sponsoring.