1 | P a g e Field Test of Plants and Fungi on Bioretention Performance over Time Contract # C1600135

To: Brandi Lubliner, RSMP/SAM Coordinator From: Alex Taylor, WSU Puyallup Graduate Research Assistant Date: April 26, 2017 Subject: Interim report for deliverable 3.3 = Design drawings and photographs of completed bioretention test cell array

We built twelve bioretention cells with a volume of 217 L (55-gallon stainless steel drums, 22.5 in. diameter, 33.375 in. height), each containing a 5 cm (2 in.) diameter slotted underdrain (commercial well casing pipe). The drain pipe was installed such that the trough of the pipe was 3.8 cm (1.5 in.) above bottom of the drum. The drain pipe was imbedded in layer of City of Seattle type 26 drain aggregate such that the gravel drainage layer extended 15.2 cm (6 in.) above the crown of the pipe. The total drainage layer depth was 24 cm (9.5 in.). Bioretention soil media (BSM) was added to each drum based on total dry mass (145 ± 2.8 kg) and was tamped down to achieve a compaction roughly equivalent to 85% of the modified maximum dry density (as defined by ASTM D1557) per Stormwater Management Manual for Western Washington (SMMWW) specifications. This compaction resulted in a BSM bulk density of 1.41 ± 0.04 g/cc and soil depth of 40.1 ± 1.0 cm (15.8 ± 0.4 in.).

Six of the twelve bioretention cells were planted with Pacific Ninebark (Physocarpus capitatus). Each planted drum received three small (130 ± 90 g each) bareroot transplants. Plants were divided among the drums by plant bareroot biomass such that each planted drum received a total of 400 ± 50 g of Pacific Ninebark. All twelve bioretention cells received a three-inch layer of Alder (Alnus rubra) mulch (60% wood chips, 40% coarse sawdust by volume). Mulch was distributed by wet mass (10 ± 0.4 kg per bioretention cell). Six of the cells were inoculated with mycelium of the wine cap mushroom (Stropharia rugoso-annulata). The alder mulch and fungal inoculum were donated by Fungi Perfecti, LLC. Inoculated drums received 6.6 ± 0.3 kg of mycelium-infused Alder mulch plus 3.4 ± 0.1 kg of Alder mulch without added fungal mycelium. Every bioretention cell was equipped with a probe to measure soil moisture, temperature, and electrical conductivity (Decagon Devices 5TE); a probe to measure soil matric (water) potential (Decagon Devices MPS6), and corresponding digital data loggers (Decagon Devices EM50). Soil probes were placed in the center area of each drum after 50% of the soil mass had been added (approximately 20 cm (7.9 in.) below the soil surface). A peristaltic pumping system was installed by collaborating King County staff to distribute runoff and log total runoff flow from a storm vault to each of the bioretention cells.

2 | P a g e Field Test of Plants and Fungi on Bioretention Performance over Time Contract # C1600135

Figure 1: Location of the bioretention test cell array within the WSDOT Ship Canal Research Facility

Bioretention Study Area

pump

3 | P a g e Field Test of Plants and Fungi on Bioretention Performance over Time Contract # C1600135

Figure 2: Design schematic

Random distribution of treatments within the 12 bioretention cell array: n = 3 + plants / - fungi n = 3 - plants / + fungi n = 3 + plants / + fungi n = 3 - plants / - fungi

4 | P a g e Field Test of Plants and Fungi on Bioretention Performance over Time Contract # C1600135

Figure 3: Cleared installation after weeds and debris were removed

5 | P a g e Field Test of Plants and Fungi on Bioretention Performance over Time Contract # C1600135

Figure 4: Placing drums and installation of retaining fence

6 | P a g e Field Test of Plants and Fungi on Bioretention Performance over Time Contract # C1600135

Figure 5: Delivery of clean fill for leveling installation site and filling around drums for thermal stability

7 | P a g e Field Test of Plants and Fungi on Bioretention Performance over Time Contract # C1600135

Figure 6: Installation of drain pipes

8 | P a g e Field Test of Plants and Fungi on Bioretention Performance over Time Contract # C1600135

Figure 7: Bioretention test array viewed from the northwest after planting and installation of the stormwater influent distribution system

9 | P a g e Field Test of Plants and Fungi on Bioretention Performance over Time Contract # C1600135

Figure 8: Representative photo of mulch layer two months after inoculation with mushroom spawn

10 | P a g e Field Test of Plants and Fungi on Bioretention Performance over Time Contract # C1600135

Figure 9: Representative photo of Pacific Ninebark growth two months after planting

11 | P a g e Field Test of Plants and Fungi on Bioretention Performance over Time Contract # C1600135

Figure 10: Placement of soil probes and representative example of data logger configuration