Division 13-17-002
Native Seeding
Sections:
13-17-002-0001 Description
13-17-002-0002 Definitions
13-17-002-0003 Materials
13-17-002-0004 Seedbed Cultivation and Preparation
13-17-002-0005 Execution
13-17-002-0005.1 General Seeding
13-17-002-0005.2 Broadcast Seeding
13-17-002-0005.3 Mulching for Broadcast Seeding
13-17-002-0005.4 Drill Seeding
13-17-002-0005.5 Hydraulic Seeding (Hydroseeding)
13-17-002-0005.6 Watering
13-17-002-0005.7 Establishment Period
13-17-002-0001 Description
The work under this chapter shall consist of seedbed preparation, furnishing required materials, sowing seed, covering seed and proper compaction of the seedbed and other necessary operations as described herein. Work under this section shall also include temporary seeding as may be required. An establishment period may be included as part of the required work under this chapter. Area to be seeded shall include any areas adjacent to the project areas, which are disturbed by construction activities. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-17-002-0002 Definitions
"Broadcast seeding" is sowing seeds using a mechanical means often a cyclone spreader driven by a power take off or hand operation.
"Grassland drill seeding" is planting seed using a grassland drill seeder. A grassland drill has multiple seed boxes (to accommodate the variety of seed characteristics of native plants), creates a furrow, meters and drops the seed, sets the seed to a specific depth, covers the seed and firms the seedbed in one (1) action.
"Hydraulic seeding," more commonly known as hydroseeding, distributes seed and mulch in one (1) operation through a water-based slurry system with a tacking agent.
"Pure live seed (PLS)" is a percentage of pure seed that will germinate expressed as a percentage of a given weight of seed thereby providing a basis for comparing seed lots that differ in purity and germination. PLS provides for a means to adjust seeding rates. Purity and germination rate are from the seed tag or analysis report.
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Pure Live Seed (PLS) = |
Percent Purity x Percent Germination Rate/100 |
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Quantity of PLS = |
Lbs. of Seed x (Percent Purity x Percent Germination Rate) |
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Seeding Rate for Mixture = |
Percent of Plant in Seed Mix x Lbs. of PLS/Acre |
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Bulk Weight of Seed per Unit Area (e.g., acre, 1,000 SF) = |
Recommended Seeding Rate PLS in Lbs. per Unit Area/Percent PLS |
(Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-17-002-0003 Materials
A. Delivery. Deliver mulch and tackifier materials in original, unopened, undamaged containers, showing weight, analysis (if applicable) and name of manufacturer. Material shall be stored to prevent wetting and deterioration. Submit manufacturer’s product data for tackifier and wood fiber mulch.
Seed shall be delivered in standard, sealed, undamaged containers. Each container shall be labeled in accordance with Arizona Revised Statutes and U.S. Department of Agriculture rules and regulations under the Federal Seed Act. For each seed species, submit seed supplier’s certification of variety or strain of seed, percentage by weight for purity, germination, pure live seed (PLS), weed seed content and the date of analysis. Date of analysis shall not be more than nine (9) months prior to the delivery date.
B. Seed. Seed shall be fresh, clean and latest season’s crop. Legume seed shall be inoculated with appropriate bacteria cultures in accordance with the manufacturer’s instructions. Manufacturer’s preinoculated seed with protective coating may be used. Contractor inoculated seed that is not sown within eight (8) hours shall be inoculated again. Seed rates are expressed as ounces of pure live seed (PLS) per one thousand (1,000) square feet. The seed mix shall consist of the following species mix of all grasses plus five (5) flowers plus one (1) nurse crop:
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Grasses |
Percentage of Total Mix |
25# Total/Acre |
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Bouteloua curtipendula |
Sideoats Grama Grass |
12% |
3# PLS/Acre |
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Bouteloua dactyloides |
Buffalo Grass |
36% |
9# PLS/Acre |
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Bouteloua gracilis |
Blue Grama Grass |
20% |
5# PLS/Acre |
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Festuca arizonica |
Arizona Fescue |
16% |
4# PLS/Acre |
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Festuca ovina |
Sheep Fescue |
16% |
4# PLS/Acre |
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Flowers |
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16# Total/Acre |
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Achillea millefolium occidentalis |
Western Yarrow |
1.5# PLS/Acre |
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Aster bigloveii |
Purple Aster |
1.5# PLS/Acre |
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Coreopsis tinctoria |
Plains Coreopsis |
1# PLS/Acre |
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Echinacea purpurea |
Purple Coneflower |
.5# PLS/Acre |
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Erigeron speciosus |
Fleabane |
.5# PLS/Acre |
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Eschscholzia californica |
California Poppy |
1.5# PLS/Acre |
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Gaillardia aristata |
Blanket Flower |
.5# PLS/Acre |
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Gaillardia pinnatifida |
Adobe Blanket Flower |
.5# PLS/Acre |
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Gaillardia pulchella |
Fire Wheel |
.5# PLS/Acre |
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Linum perenne lewisii |
Blue Flax |
1# PLS/Acre |
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Penstemon palmeri |
Palmer Penstemon |
1# PLS/Acre |
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Penstemon strictus |
Rocky Mountain Penstemon |
2# PLS/Acre |
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Ratibida pinnata columnifera |
Prairie Coneflower |
1# PLS/Acre |
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Ratibida columnifera pulcherrima |
Mexican Hat |
1.5# PLS/Acre |
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Rudbeckia fulgida |
Black Eyed Susan |
1.5# PLS/Acre |
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Nurse Crop (added to native grass + wild flower mix) |
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Avena sativa |
Oats |
20 lbs/acre |
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Lolium multiflorum |
Annual Ryegrass |
20 lbs/acre |
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Trifolium pretence |
Red Clover |
20 lbs/acre |
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Alternative species may be acceptable but are subject to prior approval from the City Engineer or duly authorized representative.
C. Fertilizer. No fertilizer is required for native seeding.
D. Mulch. Mulch for dry application shall be straw from grain crops of the current season and shall be free of noxious weeds, mold or other objectionable material.
E. Wood Fiber. Mulch for hydraulic application (hydroseed) shall be fiber mulch consisting of specially prepared wood cellulose fiber processed to contain no growth or germination inhibiting factors. Maximum moisture content, air-dry weight, twelve percent (12%) plus or minus three percent (3%) at the time of manufacture, pH range: four and one-half (4.5) to six and one-half (6.5).
F. Tacking Agent. Tacking agent shall be an organic muciloid liquid concentrate diluted with water, containing no agents toxic to seed germination. When applied, the tacking agent shall form a transparent crust permeable by water and air.
G. Erosion Control Blankets. Erosion control blankets shall be straw, coir or a natural fiber blend. Straw blankets shall be used for cut and fill slopes that are greater than six (6) feet in height and steeper than 3:1 slopes and may be used for short-term protection during a single growing season. Natural fiber blend and coir blankets shall be used for steeper slopes, low flow channels and where protection is needed for multiple growing seasons.
H. Water. The preferred water source for hydraulic seeding shall be reclaimed water, available at various bulk loading sites. Specific locations are available from the City Utilities Department. Current utility rate charges for the reclaimed water shall apply.
I. Soil Amendments. Soil amendments shall be well-composted animal manure, plant compost or materials as approved by the City Engineer or duly appointed representative.(Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-17-002-0004 Seedbed Cultivation and Preparation
When required, soil conditioners shall be applied and incorporated into the top six (6) to eight (8) inches of the areas to be seeded. Incorporation shall be completed prior to seedbed preparation.
All areas to be seeded that are accessible to machinery shall be tilled to a minimum depth of four (4) inches. Areas inaccessible to machinery shall be hand tilled and prepared to a minimum depth of two (2) inches. Cut slopes of 2:1 or steeper do not require tilling. Cultivation on sloping terrain shall run perpendicular to the direction to the slope. If weeds or herbaceous plant material interferes with proper seedbed preparation, the contractor shall remove them from the seedbed. Contractor shall remove and dispose of all debris and other objectionable material that may interfere with seeding operations.
The area to be seeded shall be left furrowed and all surface irregularities (e.g., rills, tire marks) shall be filled and firmed to conform to the desired cross sections.
After broadcast seeding operations, the seedbed shall be lightly rolled with a minimum of one (1) pass of a cultipacker or drag harrow to insure seed to soil contact. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-17-002-0005 Execution
13-17-002-0005.1 General Seeding
Broadcast seeding with straw mulch, drill seeding and hydraulic seeding (hydroseeding) and mechanical application are approved methods.
Seed shall be sown when conditions will promote germination and growth. Normal nonirrigated permanent seed application dates are between April 1st and June 15th and between August 15th and September 20th. Seeding work shall be performed only after planting and other work affecting ground surface is complete.
When cut or fill slopes are greater than six (6) feet in height and steeper than 3H:1V, the seeded area shall be covered with erosion control blankets. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-17-002-0005.2 Broadcast Seeding
All seed shall be thoroughly mixed prior to placement into the hopper. Use a carrier medium of damp sand to aid in distribution of seed. Sowing rates for broadcast seeding shall be twenty-five percent (25%) more than the rate specified in the seed mixes identified in Section 13-17-002-0003.
Broadcast seeding shall be performed in a two (2) pass operation with half of the seed distributed in one (1) direction and the second half sown ninety (90) degrees to the initial application. Following the broadcast application of the seed, follow with a minimum of one (1) complete rolling with a cultipacker or light drag harrow. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-17-002-0005.3 Mulching for Broadcast Seeding
Mulching for broadcast seeding shall be applied as soon as seed is sown and final rolling is complete. Mulch shall be uniformly distributed and crimped into the soil (typical anchorage is achieved using a serrated disc). The application rate for reasonably dry material shall be one and one-half (1-1/2) to two (2) tons per acre with the goal of one-half (1/2) inch depth and less than seventy percent (70%) coverage. Operations shall minimize displacement of the soil and disturbance of the design cross section.(Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-17-002-0005.4 Drill Seeding
Drill seeding shall be performed using a grassland seed drill or a no-till grassland seed drill. Grain drills are not acceptable.
No mulch application is required for drill seeding. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-17-002-0005.5 Hydraulic Seeding (Hydroseeding)
Seed application shall follow the preparation of the seedbed as described in Section 13-17-002-0004, Seedbed Cultivation and Preparation. The seed, mulch, tacking agent (when required) and water shall be combined in the proportions specified herein and allowed to mix for a minimum of five (5) minutes prior to starting application. Seed shall be applied within thirty (30) minutes after mixing with water. The mulch shall be added to the slurry after the seed and fertilizer have been added. Continuous agitation will be required. The slurry mixture shall be homogeneous and applied uniformly resulting in an even distribution of material.
Per acre application rates are as follows:
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Tacking Agent |
40# |
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Wood Fiber |
200# |
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Seed |
50% more than the rate indicated in MAG Section 430.3.2 |
Seed areas within contract limits and areas adjoining contract limits disturbed because of construction operations. Payment for seeding areas outside of contract limits shall be at contractor’s expense.
Immediately remove overspray materials which are deposited on adjacent plant materials, sidewalks, roadways, structures and areas where seeding is not specified. Materials applied to excessive depths in seeding areas shall be removed and the area reseeded as specified.
The seed, mulch, tackifier, and water shall be combined in the proportions specified herein and allowed to mix for a minimum of five (5) minutes prior to starting application. Seed shall be applied within thirty (30) minutes after mixing with water. Seed, mulch and tackifier shall be applied in a two (2) step process. All spraying applications shall maintain a uniform color and texture consistent with specified application rate.
The initial application shall be a slurry mix of water, seed and wood fiber mulch. The initial application rate shall be as follows:
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Seed shall be applied at the rates shown in MAG Section 430.3.2. |
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Wood fiber mulch shall be applied at a rate of five (5) pounds per one thousand (1,000) square feet. |
The second application shall be a slurry mix of water, wood fiber mulch and tackifier. The second application rate shall be as follows:
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Wood fiber application rate shall be forty five (45) pounds per one thousand (1,000) square feet. |
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one Tackifier application rate shall be two (2) pounds per thousand (1,000) square feet. |
(Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-17-002-0005.6 Watering
If watering is a required component of establishment and maintenance, the following watering schedule shall be followed. Water the hydroseed areas one (1) time per day for two (2) weeks, to a ground moisture depth of one-half (1/2) inch. During the third and fourth week, water the hydroseed areas three (3) times per week (every other day) to a ground moisture depth of one-half (1/2) inch. Watering for the remainder of the establishment period shall be once a week to a ground moisture depth of one-half (1/2) inch. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-17-002-0005.7 Establishment Period
Following acceptance of the seeding and mulching, the contractor shall be responsible for maintaining and stabilizing the seeded and mulched areas for a forty-five (45) calendar day period. During the establishment period, the contractor shall repair and restore eroded or damaged areas.
Within the one (1) year warranty period, the contractor shall perform two (2) mowing operations during the growing season. The cutting height shall be approximately six (6) to eight (8) inches. The mowing operation shall insure that bunching or windrowing of mowed vegetation will not occur. (Ord. 2017-22, Rep&ReEn, 07/05/2017)