From
Romin Khavari
Title
Resolution for Creek Erosion and other Drainage Policy Updates
Presenter
Romin Khavari, City Engineer and Stephanie Griffin, Storm Water Utility Manager
Recommended Action
Approve
Analysis
The floods of 2015 have caused erosion of several creeks in the City. Many residents are now affected by the Creek Erosion causing damage to their property.
Staff have looked into these concerns and made presentations to the Development Committee on January 22, 2016, the Public Safety Health and Environment Committee on February 1, 2016 and the Finance and Government Committee on February 2, 2016 and March 1, 2016, based on the recommendation of voluntary buy-outs instead of structural improvements, and to continue making public benefit improvements as recommended in the drainage master plans.
Based on the committee concurrence and input, staff briefed the City Council on March 22, 2016 about the proposed recommendation to update the proposed creek erosion policy and present to the City council for consideration:
The update and revisions to the previous policy are shown in bold font below:
Erosion and/or flooding problems on private property will be investigated on a case-by-case basis. The City will focus on improvements to the waterways that will result in a general public benefit, such as lowering erosive velocities and increasing flow capacities in proximate streams for the general prevention of erosion and flooding and to include those improvements that are required to protect public City Utilities such and Water, Wastewater and Drainage facilities.
Remedy of private property issues, such as flooding due to lot-to-lot drainage (no involvement of City property); and construction projects to protect specific private property due to proximate stream erosion; will not be undertaken by the City unless a general public benefit or public safety concern can be demonstrated, eminent danger to Private habitable structures due to erosion based on engineering criteria for voluntary buy-out consideration and the undertaking of such are approved by the City Council.
City will encourage the property owners to purchase of flood insurance for habitable structures adjacent to rivers and creeks.
Individual projects will be evaluated and prioritized based on available funding.
The following general engineering criteria shall be followed to help determine if only the Habitable structure (excluding, fences, Sheds, Swimming pools, etc.) is in eminent danger:
1. Evident head scarp associated with a rotational slide is within three feet or less from the foundation to include the following:
a. Development of tension cracks on the slope face as well as on the top
b. Top of slope dropping leaving vertical scarp
c. Toe of slope bulging upward
2. Development of “cut bank” less than 15 feet where the top of the bank is located closer to the foundation than the height of the bank (H) plus 5 feet (H+5’).
3. For cut banks 15 feet and higher, the foundation should be a minimum distance of 1.5 times the height of the bank (H).
4. Sudden lateral and or leaning movement of site paving, retaining walls, fences or trees indicating sliding or rotation failure within three feet of the foundation.
5. Sudden foundation movement down or laterally towards a slope
6. Rupturing of utilities shortly after flood events, especially where the rupture is near the foundation or between the foundation and the failing slope.
7. Development of multiple head scarps indicating rapid progressive failure.
8. Any exposed vertical cut banks in weathered or unweathered shale where bedding planes dip towards the slope.
If the habitable structure satisfies these engineering criteria, the City will hire a Geotechnical Engineer registered in the State of Texas for a more detailed evaluation based on field bore samples.
The Following general Voluntary Buy-out procedure shall be followed:
1. City will obtain an appraisal to determine fair market value and provide opportunity for a counter offer based on the owner hiring and paying for another appraisal.
2. City will provide for relocation expenses as prescribed in the Uniform Relocation Act.
3. City will negotiate accordingly to arrive at an amicable agreement to present to the City Council for consideration.
4. The property owner shall obtain a flood insurance policy for the habitable structure under consideration to be effective and in force during the duration of the voluntary buy-out process in case of catastrophic failure. Documentation shall be provided by the property owner to the City.
Upon the successful voluntary buy-out, the city will remove the habitable structure and any improvements as deemed necessary and dedicate and maintain the property as a Storm Water Management Area.
This new Policy will update and replace the previous Policy (Resolution No, 3919) in its entirety.
Financial Consideration
Increase to the Storm Water Utility rates to pay for the public benefit improvement projects and to include the voluntary buy-outs.
Body
A RESOLUTION OF THE CITY OF GRAND PRAIRIE, TEXAS, ESTABLISHING A POLICY CONCERNING EROSION AND OTHER DRAINAGE PROBLEMS RELATING TO WATERWAYS
WHEREAS, the City Council has determined that Erosion problems along the Trinity River and Creeks in the city are of concern to the City.
NOW, THEREFORE, BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY OF GRAND PRAIRIE, TEXAS:
SECTION 1. That it is hereby determined to be in the best interests of the City of Grand Prairie, Texas and its inhabitants to adopt the following drainage policy:
Erosion and/or flooding problems on private property will be investigated on a case-by-case basis. The City will focus on improvements to the waterways that will result in a general public benefit, such as lowering erosive velocities and increasing flow capacities in proximate streams for the general prevention of erosion and flooding and to include those improvements that are required to protect public City Utilities such as Water, Wastewater and Drainage facilities.
Remedy of private property issues, such as flooding due to lot-to-lot drainage (no involvement of City property); and construction projects to protect specific private property due to proximate stream erosion; will not be undertaken by the City unless a general public benefit or public safety concern can be demonstrated, eminent danger to Private habitable structures due to erosion based on engineering criteria for voluntary buy-out consideration and the undertaking of such are subject to approval by the City Council.
City will encourage the property owners to purchase of flood insurance for habitable structures adjacent to rivers and creeks.
Individual projects will be evaluated and prioritized based on available funding.
The following general engineering criteria shall be followed to help determine if only the Habitable structure (excluding, fences, Sheds, Swimming pools, etc.) is in eminent danger:
1. Evident head scarp associated with a rotational slide is within three feet or less from the foundation to include the following:
a. Development of tension cracks on the slope face as well as on the top
b. Top of slope dropping leaving vertical scarp
c. Toe of slope bulging upward
2. Development of “cut bank” less than 15 feet where the top of the bank is located closer to the foundation than the height of the bank (H) plus 5 feet (H+5’).
3. For cut banks 15 feet and higher, the foundation should be a minimum distance of 1.5 times the height of the bank (H).
4. Sudden lateral and or leaning movement of site paving, retaining walls, fences or trees indicating sliding or rotation failure within three feet of the foundation.
5. Sudden foundation movement down or laterally towards a slope
6. Rupturing of utilities shortly after flood events, especially where the rupture is near the foundation or between the foundation and the failing slope.
7. Development of multiple head scarps indicating rapid progressive failure.
8. Any exposed vertical cut banks in weathered or unweathered shale where bedding planes dip towards the slope.
If the habitable structure satisfies these engineering criteria, the City will hire a Geotechnical Engineer registered in the State of Texas for a more detailed evaluation based on field bore samples.
The Following general Voluntary Buy-out procedure shall be followed:
1. City will obtain an appraisal to determine fair market value and provide opportunity for a counter offer based on the owner hiring and paying for another appraisal.
2. City will provide for relocation expenses as prescribed in the Uniform Relocation Act.
3. City will negotiate accordingly to arrive at an amicable agreement to present to the City Council for consideration.
4. The property owner shall obtain a flood insurance policy for the habitable structure under consideration to be effective and in force during the duration of the voluntary buy-out process in case of catastrophic failure. Documentation shall be provided by the property owner to the City.
Upon the successful voluntary buy-out, the city will remove the habitable structure and any improvements as deemed necessary and dedicate and maintain the property as a Storm Water Management Area.
SECTION 2. That this new Policy will update and replace the previous Policy (Resolution No, 3919) in its entirety and this resolution shall become effective immediately upon its passage and approval.
PASSED AND APPROVED BY THE CITY COUNCIL OF THE CITY OF GRAND PRAIRIE, TEXAS, ON THIS THE 5TH DAY OF APRIL, 2016.