Item 9B - Zielke Oppostion ReportZ Professional services, LLC
Consulting Engineering a Project Management
January 6, 2022
Re: Evaluation and Opinion of Preliminary Plat — The Conservation submittal, Burney Lane, Southlake,
Texas. Case No. ZA21-0099
At the request of area property owners ZPS has performed a preliminary investigation and offers the
following observations and opinions regarding some utilities and access impacted by the proposed
Preliminary Plat of the Conservation.
Background:
The roughly 200 acre Harbor Oaks Neighborhood/Area(HON) where The Conservation is proposed, is
served by a single point of roadway access (2 lane residential) and water main (8") originating at N. Carroll
Ave. and Burney lane. This single point of access and water main serves approximately 80 existing homes
with additional potential to add homes on existing platted and vacant land. Over 2 miles of existing internal
water main and roadway are serviced through this single point with a single existing long run dead end of
4,600 liner feet and an overall diagonal straight line distance of 1,750+/-. Proposed development would add
7 lots and a 650+/- linear foot of dead end road/waterline.
Observation 1 — Service Capability of a Single Served Water System.
A water system that serves this large an area with this many homes should have a minimum of two
points of service per recognized engineering standards and government codes as well as for the obvious
reasons: 1) Redundancy in points of service allows for the possible interruption of service on one of the
service points. 2) Because a water system is a dynamic system that has to constantly react to varying allows
a system to efficiently maintain the two key components to providing adequate service and fire -flows, those
being both pressure and flow volume.
A dynamic water system modeling exercise is typically performed by an engineer to determine
system adequacy and system deficiencies, if any. Any such existing analysis on the system was not
discovered.
NOTE: The typical pressure and flow tests performed by Fire Department staff at specific points in location
and time to do not evaluate a dynamic impact on the rest of the system. In a dual fed system already studied
and determined to have dynamic adequacy or designed to have dynamic adequacy, these types of tests are
frequently all that is needed to evaluate service point capability. This does not appear to be the case for this
system.
Observation 2 — Single Point of Access Requirements per recognized codes
The single roadway access to the number of already platted lots is unsafe and does not meet the
requirements of accepted planning, engineering and fire code standards. This currently unsafe situation is
problematic and should be considered before allowing any additional development to add load/impact to the
roadway and utility system. One significant issue with a single point of access is emergency vehicle
availability and response times. If the single point of access were to experience an access interruption
(accident, other service vehicles parked, tree or weather debris, house fire, etc etc.) response times would
likely be significantly affected with no other option to access the area.
NOTE: A 2018 International Fire Code Appendix D exert is:
D107.1: "One or two-family dwelling residential development: Developments of one or two family dwellings
where the number of dwelling units exceeds 30 shall be provided with two separate and approved fire
apparatus access roads.
EXCEPTIONS:
1) Where there are more than 30 dwelling units on a single public or private fire apparatus access
road and all dwelling units are equipped throughout with an approved automatic sprinkler system
in accordance with Section 903.3.1.1, 903.3.1.2, or 903.3.1.3, access from two directions shall
not be required.
1111 Main Street, Suite 129 - Grapevine, TX 76051-214-502-7209 -
FROM POSSIBILITY TO ACTUALITY
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2) The number of dwelling units on a single fire apparatus access road shall not be increased
unless fire access roads will connect with future development, as determined by the fire code
official."
Based on experience with multiple area municipalities it is our opinion that the code intends, and is typically
interpreted to mean, that all dwellings impacted should be equipped with an approved automatic sprinkler
system before considering the exception not just those dwelling units considered for a current phase to allow
this exception.
In addition the Fire Code exception does not specifically address service issues of emergency vehicles other
than for fire protection. The parallel concern for access by emergency medical etc. should also be taken into
consideration.
CONCLUSION;
A dynamic water system modeling evaluation should be performed by a qualified engineer and system
adequacy determined before consideration of approving any additional impact to the system. If system
deficiencies are determined they should be addressed by the City and/or future development before
approving any additional impact.
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Rodney Zielke P.E. TX 50050
1111 Main Street, Suite 129 • Grapevine, TX 76051 •214-502-7209
FROM POSSIBILITY TO ACTUALITY