Green Street Maintenance Program & Lessons Learned

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1 Green Street Maintenance Program & Lessons Learned Watershed Revegetation Program Bureau of Environmental Services Summer 2018 Watershed Revegetation Program Since 1995 Natural Area Restoration and Stormwater Management in all PDX watersheds Overall goal of water quality, habitat enhancement Site Portfolio Natural areas, WQFs (ponds), SMFs (Raingardens and Green streets) Environmental Services l Green Street Maintenance Lessons Learned 2 1

2 Green Streets in LTM Over 2,000 Green Street assets in PDX ROW 1,600 trees in facilities 5 full time staff manage multiple contracts for establishment and long term maintenance Environmental Services l Green Street Maintenance Lessons Learned 3 Lessons Learned Maintenance Construction Public Involvement Environmental Services l Green Street Maintenance Lessons Learned 4 2

3 Long Term Maintenance Maintenance Activities Routine maintenance (3 4 times/year) Inlet cleaning and sediment removal Leaf and trash removal Weeding Periodic maintenance (as needed) Tree and shrub pruning Irrigation Repair Activities Replanting: Plant coverage or health below service level Structural damage Environmental Services l Green Street Maintenance Lessons Learned 5 Inspection and Condition Assessment Add info here Standardized condition assessment of green streets Created observation and severity codes Created document with photos for the various observation + severity combinations Environmental Services l Green Street Maintenance Lessons Learned 6 3

4 Good INLETS VEGETATION COVER & HEALTH SEDIMENT Poor Environmental Services l Green Street Maintenance Lessons Learned 7 Maintenance Topics Covered: Planters and Swales Inlets Trench Grates Forebays Splash Pads Check Dams Overflow Inlets Soils Rock Galleries Soil Subsidence Plants Trees Safety Environmental Services l Green Street Maintenance Lessons Learned 8 4

5 Planters and Swales Swales may cost less to build, but more costly to maintain. Zone A Treatment area Zone B Irrigation Weed Intrusion Soil Subsidence Pedestrian Damage Zone A Zone B Environmental Services l Green Street Maintenance Lessons Learned 9 Planters and Swales Advantages of planters Zone A only Less soil subsidence Plant installation simpler Less weed intrusion Flood irrigation Typical planter Environmental Services l Green Street Maintenance Lessons Learned 10 5

6 Planters and Swales Planters preferred for ease of maintenance, less foot traffic, fewer structural issues Upland planting areas (Zone B) should be minimized Planters provide a more efficient sizing smaller footprint Swale Planter Environmental Services l Green Street Maintenance Lessons Learned 11 Inlets Must allow water to easily enter facility wide opening is better All inlets will clog must be easy to clean Steep slopes and 90 turns can cause water to bypass inlet Easy to clog Environmental Services l Green Street Maintenance Lessons Learned 12 6

7 Trench Grates Trenches clog easier than an open inlet. Narrow facilities & long trenches necessitate working in the street Environmental Services l Green Street Maintenance Lessons Learned 13 Trench Grates Grates should be removable Tamper resistant vs. hex head bolts Traffic Rated Easy to lift Environmental Services l Green Street Maintenance Lessons Learned 14 7

8 Trench Grates Trenches complicate cleaning and may require specialized tools Environmental Services l Green Street Maintenance Lessons Learned 15 Forebays Use on high traffic streets or where there are sediment concerns No forebay Forebay working properly Environmental Services l Green Street Maintenance Lessons Learned 16 8

9 Forebays Slots, not weep holes Slots should be ~2 wide Concrete bottom Multiple slots are best Correct slot Slot not deep enough Environmental Services l Green Street Maintenance Lessons Learned 17 Splash Pads Eliminate the dead space between splash pad and facility wall Hard to grow and maintain plants Complicated liner installation If <18, extend splash pad to back wall. Dead Space Environmental Services l Green Street Maintenance Lessons Learned 18 9

10 Splash Pads Easy to clean No dead space Environmental Services l Green Street Maintenance Lessons Learned 19 Check Dams Wood PROS Best for retrofits Easy to adjust if needed Inexpensive Environmental Services l Green Street Maintenance Lessons Learned 20 10

11 Check Dams Wood CONS Damages easily Susceptible to rot Damages easily Susceptible to rot Environmental Services l Green Street Maintenance Lessons Learned 21 Check Dams Wood CONS Gaps at the ends are problematic Environmental Services l Green Street Maintenance Lessons Learned 22 11

12 Check Dams Concrete PROS Durable and lowmaintenance CONS Static material; costly to change More expensive than wood Environmental Services l Green Street Maintenance Lessons Learned 23 Check Dams Necessary? Notch placement Height of the check dam Top bay (upstream) gets water at every event bottom bay is often dry during average event Environmental Services l Green Street Maintenance Lessons Learned 24 12

13 Step out Zones Need to provide stable surface for people to exit cars Key Points: If you build it, people will walk there Protect the City s infrastructure investment Needs to be durable and reduce maintenance Neighbors build retrofit Potential trip hazard Environmental Services l Green Street Maintenance Lessons Learned 25 Step out Zones Lessons Learned Rock step out zones subside, more maintenance 12 Concrete step out more durable and low maintenance Concrete is maintenance free Retrofit better than nothing Environmental Services l Green Street Maintenance Lessons Learned 26 13

14 Overflow Drain Inlets Lessons Learned Specify beehive covers with larger openings Preferred Clogs easier Environmental Services l Green Street Maintenance Lessons Learned 27 Soils <10% typical 66% sand 33% compost sand and compost 5-15% fines required ingredients result Environmental Services l Green Street Maintenance Lessons Learned 28 14

15 Soils Uniformity is not desirable Compaction happens Providing for healthy plants increases longevity and lowers maintenance costs Environmental Services l Green Street Maintenance Lessons Learned 29 Soils Continue experimenting with composition of blended media and other soil amendments to improve plant health and vigor Give plants more access to native soils Balance infiltration rates with soil conditions that support plant health Environmental Services l Green Street Maintenance Lessons Learned 30 15

16 Soils PSU water quality bench tests MTL soil and underdrain tests Columbia Slough Outfall 104B soil and underdrain monitoring project Environmental Services l Green Street Maintenance Lessons Learned 31 Rock Galleries Found in lined and unlined facilities Provides storage to meet requirements for 10 year disposal (up to 4 ft. deep) Bedding for perforated drain pipes Where necessary? Environmental Services l Green Street Maintenance Lessons Learned 32 16

17 Rock Galleries Current specification Choker coarse 3 of no.4 ¾ aggregate Drain rock ¾ 1 ½ open graded aggregate Environmental Services l Green Street Maintenance Lessons Learned 33 Rock Galleries Environmental Services l Green Street Maintenance Lessons Learned 34 17

18 Rock Galleries Drought related stress observed in plants in facilities with rock galleries May also be contributing to soil subsidence Environmental Services l Green Street Maintenance Lessons Learned 35 Soil Subsidence ~10% of SMFs have some amount of soil subsidence Undermines sidewalk Exposes the liner to UV light Soil eroding from slopes raises the grade of the swale bottom, reducing storage Creates a pedestrian hazard along the sidewalk Environmental Services l Green Street Maintenance Lessons Learned 36 18

19 Soil Subsidence Contributing factors Sheet flow from sidewalk Lack of soil compaction at installation Losing soil into rock gallery Hand weeding Foot traffic Soil composition Environmental Services l Green Street Maintenance Lessons Learned 37 Plants in SMFs Environmental Services l Green Street Maintenance Lessons Learned 38 19

20 Plants in SMFs Plants perform many functions Erosion control, filtering of pollutants, infiltration Juncus patens Mahonia repens Spiraea cultivars Carex obnupta Cornus sericea Kelseyi Liriope muscari Photos courtesy of Oregon State University and Sevenoaks Native Nursery Environmental Services l Green Street Maintenance Lessons Learned 39 Plants in SMFs Irrigation (postestablishment) is an ongoing cost Lined facilities 21% of our green street irrigation expense for 2015 went toward watering lined facilities (9% of inventory) Environmental Services l Green Street Maintenance Lessons Learned 40 20

21 Plants in SMFs Lessons Learned Irrigation Benefits Summer 2015 July 8 August 9 September 24 Environmental Services l Green Street Maintenance Lessons Learned 41 Trees in SMFs SMFs are difficult environments for trees Poor soil Large rock galleries Dry summers Standing water in winter Inlet blocked by roots Environmental Services l Green Street Maintenance Lessons Learned 42 21

22 Trees in SMFs Building new facilities around existing trees creates challenges: Construction, tree protection Added stress to tree Roots can disrupt flow through facility and cause structural damage Environmental Services l Green Street Maintenance Lessons Learned 43 Trees in SMFs Right tree, right place Develop criteria for when to plant a tree in a facility Plant trees outside of the facility when possible Environmental Services l Green Street Maintenance Lessons Learned 44 22

23 Safety and Maintenance Access Access Worker safety High speed traffic on arterials Visibility Issues Median facilities Dangerous where street side work is required Must cross road especially inlet and gutter cleaning No access or clearance Parking violation Environmental Services l Green Street Maintenance Lessons Learned 45 Safety and Maintenance Access Spotters, flaggers, travel to and from vehicle Time consuming and costly Complicated loading and unloading 40 MPH zone SE 47th and Everett - Bike lane Environmental Services l Green Street Maintenance Lessons Learned 46 23

24 Safety and Pedestrians Soil Subsidence Creates a pedestrian hazard along the sidewalk Undermined sidewalk Unprotected drop from sidewalk Environmental Services l Green Street Maintenance Lessons Learned 47 Public Engagement Green Streets generate a lot of public interest, comments, and concerns. Maintenance crews, Reveg, CIP inspection staff, and staff outreaching to the public interact regularly with interested and/or concerned neighbors. Environmental Services l Green Street Maintenance Lessons Learned 48 24

25 Public Engagement CIP projects have outreach, Public Works Permitting projects typically don t Environmental Services l Green Street Maintenance Lessons Learned 49 Public Engagement APO expectations Aesthetics BES expectations stormwater function VS. SPRING WINTER Environmental Services l Green Street Maintenance Lessons Learned 50 25

26 Public Engagement Visibility thru the seasons Visibility Early expectations Resident s modifications Environmental Services l Green Street Maintenance Lessons Learned 51 Public Engagement Green Street Steward program is crucial towards developing good relationships 432 Green Streets adopted 182 Registered Green Street Stewards (40 Businesses) Environmental Services l Green Street Maintenance Lessons Learned 52 26

27 Regional stormwater facilities (parcels) Think outside the green street Ponds, wetlands and swales with very large catchment areas Not as highly visible as green streets Managed as natural systems allowing nature to do the work Can use native plants, no height constraints Plants have access to native soils Typically don t have to irrigate Typically requires pipe infrastructure to deliver stormwater FY facilities, 141 acres, typically underspent Much less intensive to maintain than green streets in the ROW Environmental Services l Green Street Maintenance Lessons Learned 53 Questions? Environmental Services l Green Street Maintenance Lessons Learned 54 27