MPDP VEGETATION ADVISORY WORKGROUP WORKSHOP #5

Transcription

1 MPDP VEGETATION ADVISORY WORKGROUP WORKSHOP #5 DATE: TO: LOCATION: April 21, 215 MPDP Vegetation Advisory Workgroup SWA Group Office, 1245 West 18 th Street Meeting Purpose: Review Workgroup Activities Develop Considerations for Planting Plan Implementation Review Communications The following summary presents the general discussion topics and proceedings from the meeting. 1. Introduction and Check-In The topic of discussion in Workgroup Meeting #5 is to refine the proposed implementation strategies with specific attention to timing considerations and construction methods. a. The Workgroup members were asked to participate in a videography interview, as well as to assist with the continuation of plot assessments on site. i. Eight of the thirty-two biological assessment plots were recorded in the first field effort. Additional field work will be scheduled. b. Of the six Workgroup members in attendance, five expressed interest in participating in both volunteer opportunities. c. Appreciation was expressed toward the Workgroup members for their flexibility as the coming meeting dates were adjusted to allow for more thorough data compilation between gatherings. 2. Existing Conditions A synopsis of the existing conditions will be available to the public. Thus far, an outline of the document has been developed by SWA and coordinated with HCFCD. Additional data will be required to complete the synopsis, including a biological assessment and a hydroperiod analysis. a. Biological Assessment: i. A biological assessment of understory and midstory vegetation in representative plots was started last week. Additional field work will be needed to complete this supplemental plant community assessment. ii. During the first field assessment, the Workgroup participants agreed on the following methods: 1. A stem count of all the woody vegetation from one inch up to eight inches within a twenty-foot radius plot. 2. Percent cover of all woody species less than one inch within the 26- foot plot. 3. List all regenerative seedling species that represent potential desirable overstory vegetation, if present. April 21, 215 Page 1

2 MPDP VEGETATION ADVISORY WORKGROUP WORKSHOP #5 4. Percent cover of all herbaceous species within an eleven-foot radius plot. b. Hydroperiod Analysis (See Attachment A.) i. Annual flow duration pattern for the years , as recorded at the USGS gage at Shepherd Dr., based on the 15 minute data from the USGS. ii. The chart below documents annual averages of when and how long those flow elevations exceeded the mid-toe elevation of nine feet. Year 9 to 13 (hrs) 9 to 13 (days) Above 13 (hrs) Above 13 (days) Average iii. This data informs the Workgroup of how long the vegetation from mid-toe up to bankfull may be inundated. iv. The data from 28 includes flow rate data affected by Hurricane Ike. v. The data from 211 was influenced by the drought. vi. Additional analysis of the lower toe (6.5 to 9 foot) was recommended. 3. Planting Plan Inputs The Workgroup was asked to discuss and brainstorm options for the planting plan. a. SWA showed a conceptual exhibit identifying the following planting areas: toeprotection on the inside and outside bends, bankfull bench on the inside and outside bend areas, upper slopes, and wetlands. Total calculated acreages were compiled for each planting area. b. The proposed seed mix for the project was distributed to the group prior to the meeting for comment. c. The Workgroup also discussed strategies to employ in planting, as summarized below. d. The Workgroup was reminded that this effort could develop a new standard of planting for the region. 4. General Construction and Planting Strategies Responsibility of planting will be shared by the Construction Contractor, Tree Planting Contractor, and Wetland Contractor. The Workgroup explored additional options for supplemental planting. a. Tree protection and preservation will be determined simultaneously on site prior to construction. At that time, the project site will be reviewed in phases with a certified arborist, urban forester, City of Houston officials, park officials, and the contractor to identify and minimize impacts, making minor adjustments to slope grading where April 21, 215 Page 2

3 MPDP VEGETATION ADVISORY WORKGROUP WORKSHOP #5 possible, and utilizing soft access methods (mulch beds) to cross pre-identified critical root zones. b. It is anticipated that there will be six phases of construction work performed by the contractor. c. The project is a balanced cut and fill (meaning all soil excavated from the channel will be used within the streambed). A minimal amount of select fill may be brought in for specific applications. d. How the contractor will cross to the south side of the project area is still being examined. e. Topsoil will be kept separate during excavation. f. To establish a stable channel pattern, compaction rates of soil will vary to promote vegetation growth depending on the flow impact on the area. g. The soil compaction in the coir lift areas will be determined in the field in order to account for live-stake vegetation success. h. After construction is complete, a separate HCFCD Contractor will be responsible for wetland planting. i. Post construction, a separate HCFCD contractor will be responsible for seedling and tree planting. j. Public volunteer tree planting is a possibility. As discussed in the previous meeting, public outreach for long-term maintenance and monitoring, would need to be an organized effort. k. Trees for Houston has expressed interest in assisting with plant materials. Any parties interested in donating materials to the revegetation efforts will need to coordinate with HCFCD for necessary approvals prior to doing so. l. The Trash Bash event was discussed as a possible model for organizing an annual event concerning planting or maintenance along the project reach. m. The Workgroup will be recommending long-term vegetation maintenance options and responsibilities. 5. Planting Sequencing The Workgroup discussed installation methods for each planting area. a. Toe Wood Sequencing: i. The base of the toe wood is installed below base flow elevation. ii. Construction will involve footer logs and root wads that face towards the stream center at a slight angle. iii. Depending on seasonality, live brush mattresses will be placed above the toe wood to fill the voids. iv. Temporary counter weights will be used as the contractor backfills on-site material to create coir lifts above the installed toe wood. v. Additional to the live brush mattresses, live stakes and other live material (fresh cuttings) will be scattered over the first few layers of coir lifts. vi. Live brush plant list to include: 1. Black Willow 2. Cottonwood 3. Buttonbush 4. Boxelder April 21, 215 Page 3

4 MPDP VEGETATION ADVISORY WORKGROUP WORKSHOP #5 5. Green ash 6. Bald Cypress 7. Sycamore 8. River birch 9. Water Elm (seeding source dependent) vii. Inside bend plantings will be lighter. viii. Outside bend plantings will be dense brush. ix. Live brush cuttings could potentially be harvested from HCFCD property (e.g., Keith-Wiess Park). b. Coir Lift Installation i. Coir lifts will be built up above the toe wood and live mattress. ii. Each lift is about 1 to 1-1/2 feet high with live fascines or live stakes installed in between. List of live fascine/stake plant suggestions are similar to live brush material used in the toe wood construction. iii. Coir lift installation occurs on the outside bends. 1. If construction occurs in June to September (summer season), live fascines/stakes will be installed along with bunchgrasses in between each lift. 2. Install grass plugs along with live stakes. Workgroup species suggestions included: inland sea oats, Canadian wild rye, switchgrass, eastern gamagrass, and Arundaria gigantean (giant cane) 3. If construction occurs in the summer season, installation of live stakes and bunchgrasses will have to wait until October. 4. Current specifications state that plant materials critical to bank stabilization components, such as VSE walls, coir lifts and toe wood installation shall be installed immediately upon installation of the components. However, this needs to be revised to provide flexibility for ultimate vegetation success. iv. Outside bends will generally have a steeper slope (2H:1V) planting will also include containerized and/or bare root seedlings at the upper third of the coir lifts. v. Inside bends will generally have a gentler slope (4H:1V) planting to include: 1. Bare dirt (low flow up to bankfull) 2. Coir fabric will then be laid over the top 3. Install live stakes (approximate length: 3-4 feet; one foot up, two feet below) vi. Riffle runs will be graded to be uniform on both sides. After grading, 18 in. of topsoil will be tilled for seeding purposes. c. The Workgroup expressed continued concern for expected stabilization and vegetation success below 9-foot elevation. d. The group stressed the importance of vegetation at upper bank levels towards the 9- foot elevation so as not to rely completely on the toe wood for stabilization and vegetation success. e. Bankfull Bench Planting Strategies i. The average width of the bankfull bench along the project is feet. ii. The entirety of the bankfull bench will be seeded with a specific seed mix. April 21, 215 Page 4

5 MPDP VEGETATION ADVISORY WORKGROUP WORKSHOP #5 iii. Analysis shows that the water levels reach bankfull bench and above an average of 7 times a year. iv. There will be an average 1% cross grade. v. Planting density will be higher on the outside bends and lighter on the inside bends and transition (riffle) areas vi. For quick stabilization, fast growing plant material such as Sycamore, American Elm and Green Ash should be used. f. Upper Slopes Seeding and Planting i. 3:1 slope ii. Total area, approximately 3 acres iii. HCFCD and the contractor will be surveying the area as construction takes place to preserve trees that are desirable and in good condition. iv. Seed mix 1. Hydro-mulch with Bonded Fiber Matrix to hold the slopes while germination takes place. 2. Use one seed mix for bankfull bench and upper slopes 3. A comment was made regarding Bushy Bluestem being expensive, but a good species for quick germination; consider reducing the percentage of Bushy Bluestem in the seed mix. v. The plans should maintain viewsheds, where possible. vi. No erosion control (BMP) measures for slope interruption, unless long run (2 ). Possible measures to consider: 1. Compost sock 2. Wattles vii. Install Trees: 1. Mesic-xeric (moderate to low moisture requirements) 2. Hogg-Bird Sanctuary should consider bird benefits, view and aesthetic viii. The planting input in this area should integrate Memorial Park s proposed planting plan for consistency. g. Wetland Area Planting Sequence i. List was distributed in the IP h. Vegetated Stablized Earthen (VSE) Walls i. Planting schedule for this area will include lives stakes, bunch grasses and bare root seedlings, as appropriate on the upper banks. 6. Closing Reminder of future meetings and activities 7. Adjourn a. The next meeting to discuss the Riparian Monitoring Plan is set for Tuesday, May 12, 215. b. The upcoming biological assessment field day was scheduled within the coming week. Volunteers were requested to help out. c. The Workgroup was reminded that Meeting Notes will be distributed to the group once the internal review is complete. d. Once final, Workgroup Meeting Notes will be posted to the website for public viewing. April 21, 215 Page 5

6 Attachment A Hydroperiod Analysis

7 /13 (Ike) hours hrs = 4.6 days hrs = 18.3 days 7/ hours 8/ hours / hours 11/ hours Jan 143 hrs Feb 66 hrs Mar 33.5 hrs May.75 hrs Jul 9.5 hrs Aug 62 hrs Sep hrs Oct hrs Nov 7 hrs 5 12/24/27 : 2/12/28 : 4/2/28 : 5/22/28 : 7/11/28 : 8/3/28 : /19/28 : 12/8/28 :

8 hrs = 3.9 days 4/ hours 4/ hrs /22.5 hrs / hrs /3 9.5 hrs hrs = days 4/18.25 hrs 4/19 5 hrs 4/25 14 hrs 4/ hrs 5/3 39 hrs 5/ hrs 5/11 54 hrs 5/ hrs 5/11 54 hrs 5/ hrs 5/ hrs 5/ hrs 9/ hrs /2 13 hrs /22 7 hrs hrs /26.5 hrs /3 hrs 5 12/28/28 : 2/16/29 : 4/7/29 : 5/27/29 : 7/16/29 : 9/4/29 : /24/29 : 12/13/29 :

9 25 2 7/ hours hrs = 2. days 5/ hours 7/ hours 12/29.75 hours hrs = 3.7 days 2/11 8 hours 5/ hours 6/ hrs 6/22 5 hours 7/ hrs 7/7 7/ hours 11/ hours 12/29 6 hours 5 12/28/29 : 2/16/2 : 4/7/2 : 5/27/2 : 7/16/2 : 9/4/2 : /24/2 : 12/13/2 :

10 hrs =.4 days / 9.25 hours hrs =.8 days / 7.5hours 12/ hours /18/2 : 2/6/211 : 3/28/211 : 5/17/211 : 7/6/211 : 8/25/211 : /14/211 : 12/3/211 :

11 25 7 hrs = 4.4 days 84 hrs = 3.5 days 2 1/ hours 1/ hours 2/ hours 2/ hours 3/ hours 5/12.5 hours 7/ hours 15 Jan 12.5hrs Feb hrs Mar 8 hrs Jun 1 hr Jul hrs Aug 13 hrs Sep 5.25 hrs 5 12/22/211 : 2//212 : 3/31/212 : 5/2/212 : 7/9/212 : 8/28/212 : /17/212 : 12/6/212 :

12 Hours = 1.7 Days Hours = 3.5 Days 4/27.75 hours 9/2 18 hours / hours 1/ hours 4/ hrs 4/27 hours 5/ hours 9/ hrs /19.5 hrs / hours 11/ hrs 11/ hours 5 12/17/212 : 2/5/213 : 3/27/213 : 5/16/213 : 7/5/213 : 8/24/213 : /13/213 : 12/2/213 :

13 Hours = 2.7 Days 5/ hours 5/26 4 hours 5/27 4 hours 5/ hours 9/18 9 hours 9/ hours 12/ hours Hours = 3.9 Days 5/ hours 5/ hours 5/ hours 7/ hours 8/1 15 hours 9/17 5 hours 9/ hours 9/19 11 hours 12/ hours /22/213 : 1/11/214 : 3/2/214 : 4/21/214 : 6//214 : 7/3/214 : 9/18/214 : 11/7/214 : 12/27/214 : 2/15/215 :