City of Katy Pine Forest Public Workshop. November 7, 2017

Transcription

1 City of Katy Pine Forest Public Workshop November 7, 2017

2 Pine Forest Aerial Map with Street Names

3 Presentation Objectives The Scope of this Workshop is to: 1) Review existing drainage issues experienced in Pine Forest Subdivision and identify existing conditions that are contributing to them; 2) Explain the limitations of improving drainage relief with implementing new local drainage improvement recommendations; 3) Present the preliminary recommendations for the City of Katy to consider for local drainage improvements; 4) Summarize preliminary statement of probable costs for the recommended drainage improvements.

4 Existing Drainage Conditions External Drainage Conditions: Cypress Creek Overflow (Regional Matter) Cane Island Branch (Regional Matter) Morton Road; existing and future Avenue D Drainage Behavior Consolidated Comm. Facilities Conflict in Avenue D (Regional) Internal Drainage Conditions: Magnolia Ditch along South Perimeter of Pine Forest Subdivision Existing Topography / Sheet Flow Pattern Behavior Internal Drainage Area Collection Patterns Existing Gas Pipe Line Conflict Selective Home Slab Elevations Relative to Ex. Street Profiles Residential Roadside Ditch and Driveway Culverts

5 Pine Forest Regional Map

6 Consolidated Comm. Avenue D Conflict

7 Existing Drainage Conditions External Drainage Conditions: Cypress Creek Overflow (Regional Matter) Cane Island Branch (Regional Matter) Morton Road; existing and future Avenue D Drainage Behavior Consolidated Comm. Facilities Conflict in Avenue D (Regional) Internal Drainage Conditions: Magnolia Ditch along South Perimeter of Pine Forest Subdivision Existing Topography / Sheet Flow Pattern Behavior Internal Drainage Area Collection Patterns Existing Gas Pipe Line Conflict Selective Home Slab Elevations Relative to Ex. Street Profiles Residential Roadside Ditch and Driveway Culverts

8 Pine Forest Regional Map

9 Magnolia Ditch Looking West on Ave. D Existing 6 x3 Box Culvert Avenue D

10 Ex. Magnolia Ditch at Cane Island Creek Existing 48 HDPE

11 Magnolia Ditch Profile - Original Design Conditions

12 Existing Drainage Conditions External Drainage Conditions: Cypress Creek Overflow (Regional Matter) Cane Island Branch (Regional Matter) Morton Road; existing and future Avenue D Drainage Behavior Consolidated Comm. Facilities Conflict in Avenue D (Regional) Internal Drainage Conditions: Magnolia Ditch along South Perimeter of Pine Forest Subdivision Existing Topography / Sheet Flow Pattern Behavior Internal Drainage Area Collection Patterns Existing Gas Pipe Line Conflict Selective Home Slab Elevations Relative to Ex. Street Profiles Residential Roadside Ditch and Driveway Culverts

13 Existing Topography (by Color Chart)

14 Drainage Sub-Areas and Sheet Flow Path

15 Hackberry Lane Sheet Flow Near Pecan Ln.

16 Existing Drainage Conditions External Drainage Conditions: Cypress Creek Overflow (Regional Matter) Cane Island Branch (Regional Matter) Morton Road; existing and future Avenue D Drainage Behavior Consolidated Comm. Facilities Conflict in Avenue D (Regional) Internal Drainage Conditions: Magnolia Ditch along South Perimeter of Pine Forest Subdivision Existing Topography / Sheet Flow Pattern Behavior Internal Drainage Area Collection Patterns Existing Gas Pipe Line Conflict Selective Home Slab Elevations Relative to Ex. Street Profiles Residential Roadside Ditch and Driveway Culverts

17 Extreme Event Drainage Collection Areas

18 Existing Drainage Conditions External Drainage Conditions: Cypress Creek Overflow (Regional Matter) Cane Island Branch (Regional Matter) Morton Road; existing and future Avenue D Drainage Behavior Consolidated Comm. Facilities Conflict in Avenue D (Regional) Internal Drainage Conditions: Magnolia Ditch along South Perimeter of Pine Forest Subdivision Existing Topography / Sheet Flow Pattern Behavior Internal Drainage Area Collection Patterns Existing Gas Pipe Line Conflict Selective Home Slab Elevations Relative to Ex. Street Profiles Residential Roadside Ditch and Driveway Culverts

19 Existing Gas Pipe Line in Subdivsion:

20 Existing Drainage Conditions External Drainage Conditions: Cypress Creek Overflow (Regional Matter) Cane Island Branch (Regional Matter) Morton Road; existing and future Avenue D Drainage Behavior Consolidated Comm. Facilities Conflict in Avenue D (Regional) Internal Drainage Conditions: Magnolia Ditch along South Perimeter of Pine Forest Subdivision Existing Topography / Sheet Flow Pattern Behavior Internal Drainage Area Collection Patterns Existing Gas Pipe Line Conflict Residential Roadside Ditch and Driveway Culverts Selective Home Slab Elevations Relative to Ex. Street Profiles

21 Limitations on New Improvements The Recommendations for Improving Drainage at Pine Forest Subdivision are Limited to the following Results: 1) The Regional Issues (Cypress Creek Overflow, Cane Island Creek Capacity) are not improved with local project(s) recommended in this presentation. The Regional issues are a problem for multiple jurisdictions beyond just the City of Katy to improve by working together. When a significant rainfall event beyond the Design Storm is experienced these Regional Issues will minimize the local improvements effectiveness to move runoff into the Creek without risk of area flooding. 2) The recommended improvements are focused on updating those conditions locally at Pine Forest Subdivision to current Design Storm capacity regulations.

22 Regional Flood Reduction Strategy Reminder: Cypress Creek Third Reservoir (Plan 5, etc..) Cane Island Branch Creek Large scale regional improvements $$$$$$ channel improvements, regional detention City detention pond expansion Potentially expand CIB development pond Develop criteria and partner with BKDD to ensure responsible development upstream Local Drainage Pine Forest drainage improvements Fortuna/Patna drainage review 1st St. street and drainage improvements Morton Road drainage improvements Downtown storm sewer improvements

23 Pine Forest Drainage Recommendations (#1) Recommendations for Improving Local Drainage: 1) Improve Magnolia Ditch. *PROJECT # 1 - Removing all existing trees in the channel - Deepen the 1985 design an additional 0.6 feet - Concrete line the ditch bottom and side slopes - Replace the culvert discharge from Magnolia Ditch into Cane Island Creek with a new 7 x 5 Conc. Box. - Install a Flap Gate on the Box Discharge inside Cane Island Creek - Replace Residential Fencing along both sides of Magnolia Ditch

24 Existing and Proposed Ditch Profile

25 Ditch Cross Section Example of a Similar Ditch

26 Flap Gate Example

27 Pine Forest Drainage Recommendations (#2) Recommendations for Improving Local Drainage (Cont d): 2) Replace selective Drainage Collection System on Avenue D between Magnolia Ditch and Morton Road. *PROJECT # 2 - Challenge is the Consolidated Comm. Conflict - Approximately 1,050 feet of existing pipe will be replaced with new concrete box. - Inlet leads across Avenue D will be replaced as well.

28 Avenue D Storm Improvements PRELIMINARY ONLY NOT FOR DESIGN/CONSTRUCTION

29 Avenue D Drainage Collection from PForest

30 Pine Forest Drainage Recommendations (#3) Recommendations for Improving Local Drainage (Cont d): 3) Add a new 42 storm sewer to Assist to Relieve Pecan Lane from Hackberry Lane Drainage Runoff. *PROJECT # 3 - Challenge is for the City to Secure new Drainage Easement on Existing Lots AND have the Private Pipe Line Company to consent to allow the new drainage pipe to be located within their existing 70 foot easement. - Install Two (2) new Type E inlets at the end of Hackberry cul-de-sac with a swale connecting them.

31 HACKBERRY LN. NEW STORM SEWER

32 Gas Pipe Line Looking South from Hackberry

33 View of Gas Pipe Line North of Magnolia Ln.

34 Pine Forest Drainage Recommendations (#4) Recommendations for Improving Local Drainage (Cont d):*project # 4 4) Replace an existing storm sewer on W. Elm Circle with a new 5 x 3 drainage box to discharge into Cane Island Creek. - Challenge is dealing with existing driveways and landscaping in order to remove and replace pipe. - A flap gate at the box discharge into Cane Island Creek is also recommended.

35 WEST ELM CIR. OUTFALL REPLACEMENT

36 W. Elm Circle Outfall (Street View)

37 Recap of Recommendations #1 - #4:

38 Pine Forest Drainage Recommendations (#5) Recommendations for Improving Local Drainage (Cont d):*project # 5 5) Improve Roadside Ditch/Driveway Culvert for Pine Forest to current minimum Design Standards. -This Project cannot be undertaken until Project Nos. #1 through #4 are completed for establishing new depth and capacity. - Clean Out Ditches with additional Depth. Absolute Minimum is 18 below front yard. Absolute Maximum Depth is 4 feet below Street. - Evaluate All Driveway Culverts for depth and capacity. - Clean/Remove all existing landscape features that are in the existing street right-of-way that conflict with the road side collector ditches.

39 Typical Residential Road Side Ditch Standard

40 Estimate of Roadside Ditch Improvements

41 Statement of Probable Project Costs Note: Roadside Ditch Cleanout and Driveway Culverts Cost Unidentified at this time and are not included in this summary.