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Sam Monaco Is - 5 - 40 9 June 2017 Harvest-Lathrop Composting Facility requires that working surfaces must be constructed to allow year round equipment access without damage to the working surfaces. The combination of almost flat working surfaces, reliance on sheet flow, and onsite soils consisting predominantly of fine sands and silts does not provide conditions necessary for allowing year round equipment access during the wet season without damage to the working surface (i.e., rutting, loss of drainage slope, ponding, etc.) 7. Insufficient groundwater separation. The General Order Finding 21 found that "a substantial unsaturated zone reduces pathogen survival compared to saturated soil conditions. Fine grained(silt or clay) soil particles reduce the rate of groundwater transport and therefore are generally less likely to transport pathogens." Furthermore, Finding 21 found that "setbacks also provide attenuation of other wastewater constituents through physical, chemical, and biological processes." The Discharger's Final Technical Report Site Plan (Figure 2) at piezometer P1 reported groundwater elevation at 2.3 feet mean sea level (msl) and at geotechnical boring P2-B1 at 3.96 msl., the Discharger proposes detention pond A to have a pond bottom elevation of 3.0 feet msl adjacent to the area where piezometer P1 measured groundwater at 2.3 feet msl providing a calculated groundwater separation of 0.7 feet. Furthermore, the Discharger proposes to raise the pond bottom in the area of boring P2-B1 (see item 8 below) to 6.0 feet msl in order to provide groundwater separation of 2.04 feet msl. Groundwater measurements at P1 and P2-131 do not take into account seasonal fluctuations of groundwater elevation and does not estimate highest anticipated groundwater elevation including capillary fringe. It is entirely possible that the Discharger's proposed design could create conditions during above average wet rainfall years where groundwater elevation could intersect the bottom liner of the proposed detention ponds providing no unsaturated zone for pathogen reduction or attenuation of other wastewater constituents. 8. Insufficient detention pond B storage capacity. The Discharger's proposed detention pond B storage capacity does not comply with General Order Specifications (Specifications) specification #5 requiring Dischargers to submit a Water and Wastewater Management Plan that describes how wastewater will be managed to prevent discharge. The Discharger's Final Technical Report Water Balance Analysis (Appendix C) Table 11 for Basin B states that storage capacity of detention pond B at freeboard level is 2,046,054 gallons (6.3 acre- feet). However, in construction drawing Grading and Drainage Plan (sheet 3) the Discharger proposes detention pond B to have a "stepped" bottom with an invert elevation of 6.0 feet msl at the northwestern edge and 3.5 feet msl at the northeastern edge to provide groundwater separation along the western half of detention pond B. The Discharger did not calculate storage capacity volume accounting for shallower pond storage capacity along the western half of the detention pond. Water Board staff calculations based on the information provided in the Discharger's Final Technical Report estimate detention pond capacity at freeboard level to be approximately 1,576,000 gallons. Therefore, based on column 14 of Table 11, the Discharger would exceed the detention pond capacity encroaching into the pond's freeboard area during the months of February, March, and April. 9. Disapproved engineered alternative for pan lysimeter. The General Order Tier II Specifications#3 requires detention ponds to be constructed with a pan lysimeter monitoring device under the lowest point of the pond, or an equivalent engineered alternative specified by the Discharger and approved by the Regional Water Board. The Discharger has specified as an engineered alternative to a pan lysimeter monitoring device is four Decagon 3G (sic) soil moisture probes per detention pond spaced approximately 150 to 250 feet apart and