The objective of this agenda item is to discuss about the infrastructure improvements for Phase 1, Sec. 10 of Spillman Ranch subdivision.  The development will take place over a tract of 12.4 acres land.  City approved final plat for this property in last September and it has been recorded with Travis County recently (Travis County Official Public Records Document # 201600250).  As shown in the final plat, this new subdivision will have 42 single-family residential lots, 3 water quality lots, and 4 ‘Private Street, Drainage, and Public Utility Easement’ lots. 

The development is primarily subject to recently approved PDD Ordinance No. 304 and has to follow development standards and other conditions as described in this new ordinance.  It is also subject to Spillman Development Agreement, except as modified by the PDD Ordinance. 

The submitted construction plan is in compliance with the approved Concept plan and applicable provisions.  All key information presented for PDD and Final plat application during the City Council meeting (dated September 13, 2016) regarding property and project remains the same and there is no major variation in layout and other aspect.  

This item for site development plan was presented to City Council in the last meeting (dated December 13, 2016). At the hearing, City Council decided to delay this item to this meeting for pending issue related to design of water quality ponds. 

Below links are for the transmittal letter for the site plan (12/13/16), PDD, and final plat (09/13/16) for the subject property–

https://beecave.novusagenda.com/agendapublic/CoverSheet.aspx?ItemID=1007&MeetingID=131

https://beecave.novusagenda.com/agendapublic/CoverSheet.aspx?ItemID=868&MeetingID=107

https://beecave.novusagenda.com/agendapublic/CoverSheet.aspx?ItemID=869&MeetingID=107

You may visit the attached Power point presentation for those items.  Detailed information regarding access/traffic circulation, drainage easement along Falconhead Blvd., buffers, setback requirements, Lot/Block configuration etc. are not repeated in this transmittal letter as they are available in the above included transmittal letter for PDD application and demonstrated in the presentation slides attached as reference file.  

Furthermore, information about 'Access, Roadways, Sidewalks, and Parking' and 'Landscape Plan and Screening' are written in abridged manner in this letter as they were included in the previous transmittal letter for site plan application (1st link in the section above) and remains the same. Only items that have changes or additional information are discussed in detail in the 'Issues and Analysis' section. 

Adjacent residential lots: This site development plan does not include any above ground improvements over the adjacent two private recreation lots beside Myrtle Beach Dr. (0.93 ac.; owned by the Falconhead Golf Club).  However, it does propose installing an 8" waterline within a 15' water easement (Document # 2016165498), running through the middle of the two lots to ultimately connect the new residential subdivision to the existing 12” line on Myrtle Beach Drive.  To staff’s knowledge, the developer, the property owner, and PUA are in continued discussions about realigning the easement and water line within the lots.  If they reach consensus, a site plan amendment (for re-alignment of waterline) would be necessary and it may be eligible for administrative approval. 

Access, Roadways, Sidewalks, and Parking: There will be only one unrestricted access point onto Falconhead Blvd; aligns with existing median cut (opposite to entrance to The Grove).  Internal street width will be 28’ pavement within 50’ ROW. Streets will be privately maintained. There will be 5’ wide sidewalks on both sides of internal street.  Moreover, developer will build 5’ wide concrete sidewalk along Spillman Ranch Loop (in ROW) for the stretch of this property which will provide continuation of existing sidewalk.  No separate guest parking spaces will be provided.  Overnight parking over the streets is not allowed.  

Impervious Cover: There is no existing impervious cover. The project proposes 41.75% impervious cover of the site area.  For comparison purpose, the hotel project (as part of the previous Concept plan) had approximately 49% impervious cover. 

PDD Ordinance No. 304 states that “Impervious cover for the property shall not exceed the impervious cover limits as set out in the Spillman Agreement.”  The development agreement states that the single family residential lots will not be subject to impervious cover limits.  But, it was assumed that larger lots (e.g., approximately 80’ wide) will be developed with an average of 3,500 SF of impervious cover and smaller lots (e.g., approximately 50’ wide) will be developed with an average of 2,500 SF of impervious cover.  The proposed lots range in size from 55’ to 77’ wide, with smallest lot area as 6,100 SF and largest lot area as 9,400 SF. The project propose an average of 3,410 SF of impervious cover for each of the residential lots (irrespective of lot size) and that assumed amount includes sidewalks in front of each homes and along the streets. 

Drainage, Water Quality Treatment and Stormwater Detention: Stormwater runoff from the site drains to either Falconhead Golf course or two existing area inlet located near the intersection of Spillman Ranch Loop and Falconhead Blvd.  Since the site was originally approved for a hotel site with 49% impervious cover, the existing storm sewer system (outside this development) should be more than adequate.

The project is subject to previous NPS Ordinance 90-1 which requires 70% pollutant removal.  There will be two water quality ponds, each of which will be combination of extended detention pond followed by bio-retention pond.  

In the previous submission, the ponds were undersized for the developed condition (i.e., amount of total impervious cover within each drainage area and volume of generated runoff).  Design engineer has submitted updated drawings and calculations on Friday afternoon (01/06/17) which staff will review thoroughly.  From a quick review it appears that designer increased the overall capacity of each of the ponds to capture required runoff volume.  This expansion of capacity has been done with minor grading changes and raising of the weir.  With this new design, the average impervious cover for each of the 42 residential lots is 3,410 SF (inclusive of house, driveway, sidewalk, and any other impervious improvements such as pools and patios). Note that this impervious cover allocation for single family lots includes impervious cover for sidewalks that will be built along the roadways (and in front of the houses) and within the ‘Private Street, Drainage, and Public Utility Easement’ lots (i.e., sidewalks will not be within home lots even though most of it will be constructed at the time that houses are constructed on such lots.).  The amount of impervious cover by sidewalk in front of each lot will vary with lot width (for example, 300 SF for a 60’ wide lot).  After deducting such amount, remaining amount will be available for developments over each of the residential lots.  Based on the assumption of maintaining the maximum impervious cover within each drainage area in built-out scenarios, the ponds will meet the applicable requirements. 

There is also a small water quality lot (Lot 28, Block C; 0.14 ac.) consisting of vegetated filter strip near Myrtle Beach Drive.  Additionally, there is an existing off-site vegetative filter strip area along the rear side of Lots 20-25 of Block C.  Vegetative filters are utilized for nine lots (2.42 acres) that do not drain to the roadway and ultimately to the water quality pond proposed.  Runoff after travelling through the vegetative filter strip will travel through the golf course which was dedicated as water quality easement (Document No. 2004038180) and will achieve required level of pollutant removal.

The on-site water quality ponds will not be accompanied by adjoining detention pond.  Rather, excess runoff will travel to an existing regional detention pond.  The pond is located near highway 71 over a property beside the Austin Energy Trading Post Substation.  This pond was approved by City in 2005 and constructed shortly thereafter. The pond provides stormwater detention for portion of Falconhead with drainage exiting downstream of Spillman Ranch Loop as well as the future Domino Business Park with frontage on highway 71.  Design for this pond assumed higher impervious cover (50%) for the hotel project anticipated at that time. Therefore, the existing infrastructure can serve this development and no on-site detention controls is required for this development.

Landscape Plan and Screening: The plan depicts the trees that will be saved during infrastructure development.  It also includes proposed trees that will be planted along Falconhead Blvd., along the screening wall beside Ellie Claire Bend, and over Lot 13, Block C to screen water quality pond.  5' high screening wall will be built and necessary metal fence will be installed in the locations and along the alignment shown in the approved Concept plan. 

Utilities: Water and wastewater will be provided by the West Travis County Public Utility Agency (WTCPUA). Water service will be delivered by connecting to the existing 12” water mains in Falconhead Blvd. and Myrtle Beach Dr.  As mentioned in the first paragraph of this section, waterline (in second case ) will travel through a 15' 'Waterline Easement' over the 'Golf Club Recreational Lots' for which a permanent easement document has been recorded with Travis County Official Public Records (Document # 2016165498). Wastewater service will be delivered by tying into existing 8” wastewater line in Spillman Ranch Loop.  

The Planning and Zoning Commission unanimously recommended for your approval of this site development plan with the following conditions –

 A.    Prior to issuing Site development permit -

1. Posting fiscal security in the amount of $ 357,716.00 for NPS Permit.  
2. Posting fiscal security in the amount of $945,540.00 for infrastructure improvements.
3. Payment of permit fees.
4. Completing necessary minor updates for the site plan set.
5. Recordation of ‘‘Covenants, Conditions, and Restriction’ (CCR) document.
6.  Submission of maintenance agreement for all walls and associated landscaping, private streets, and other common areas and improvements that serve the project as a whole.
7.  Submission of draft version of license agreement (with City) for sidewalk construction within right of way and subsequent execution of this document.

 B.  Prior to final inspection - Recordation of ‘Water Quality Maintenance Plan and Integrated Pest Management Plan’ with Travis County. 

Staff recommends your approval with the above mentioned conditions.