DEPARTMENT OF NATURAL RESOURCES

Transcription

1 DEPARTMENT OF NATURAL RESOURCES Minnesota Department of Natural Resources Division of Ecological & Water Resources 500 Lafayette Road St. Paul, MN January 3, 2018 [Electronic Submittal] Tricia DeBleeckere Minnesota Public Utilities Commission 121 7th Pl E #350 St Paul, MN RE: In the Matter of the Site Permit issued for the 100 MW Aurora Distributed Solar Energy Project at Multiple Facilities in Minnesota, PUC Docket Number: E6928/GS Dear Ms. DeBleeckere, The Minnesota Department of Natural Resources (DNR) has reviewed the 2018 Adaptive Management Vegetation Maintenance Plans {AMVMP}, the seeding mixes, and the 2017 Revised Agricultural Impact Mitigation and Vegetation Management Plan {AIMP/VMP} for the Aurora Distributed Solar Energy Project. The DNR has comments and recommendations regarding the AMVMP and the seeding mixes. Our agency had no comments on the 2017 Revised AIMP/VMP Adaptive Management Vegetation Maintenance Plans (AMVMP) The DNR's review follows the same order as the subheadings in the AMVMP: Plan Amendments The AMVMP states that it will be updated at least annually until sites reach final restoration. Please clarify what is meant by final restoration and explain the criteria used to determine when final restoration has been achieved. From the DNR's perspective, plan amendments would not be necessary after the establishment phase has successfully been accomplished (3-5 years). Vegetation Monitoring The first sentence in the second paragraph should be revised to read, "Vegetation Monitoring Reports will be prepared by an experienced native plant community restoration company and reviewed by Barr Engineering." DNR recommends clarifying the responsibilities of the identified restoration company for implementation of the plan following Barr's approval. It is important to acknowledge that there are specific timeframes for treating invasive species to achieve success. Hence, if monitoring, reporting, and analysis take a long time, then the prime window to conduct necessary maintenance may be missed. Minnesota Department of Natural Resources Division of Ecological & Water Resources 500 Lafayette Road, St. Paul, Minnesota

2 The DNR recommends that the AMVMP differentiate between vegetation monitoring during the establishment phase and during the maintenance phase, perhaps using a separate heading for each phase. While the establishment phase is 1-3 years, 3 years and beyond is considered the maintenance phase where management could be necessary depending on weed pressure, tree growth, invasive species, native plant health, and other factors. There will likely be ongoing maintenance associated with this project for its lifetime. Discussion of the establishment phase should recognize that the duration of this phase will likely vary given the wide variety of site conditions. Specific criteria should be identified to determine when establishment has been attained. Once sites reach the maintenance phase, discussions should occur regarding the extent of monitoring and reporting necessary. The DNR's previous comment letter (August 10, 2017) included recommendations for the maintenance phase. Our agency reiterates the importance of establishing a timeline for when monitoring will occur and how it will be accomplished. Aurora's August 15, 2017 reply letter stated that the permittee intends to utilize the BWSR pollinator assessment form during the maintenance phase. It is the DNR's understanding that Aurora proposes to initiate the assessment of each site using the BWSR pollinator assessment form starting in year three after permanent seeding has been completed. Aurora proposes to re-assess each site using the BWSR pollinator assessment form every five years thereafter for the life of the project. The DNR recommends including this commitment in the AMVMP. The outcome of the maintenance monitoring could assist the Public Utilities Commission in determining at what point environmental inspections are no longer warranted. Vegetation Disturbance The fourth sentence in this section should be revised to read, "It will be necessary to drive equipment on the native vegetation, which can will impact its growth." The second sentence in the third paragraph should be revised to read, "The plantings will in effect be starting over at the disturbance location." Vegetation Management Priorities The first sentence seems to imply that weeds are insurmountable, when in actuality, many weeds are winter annuals that commonly appear at disturbed sites, but are unsuccessful over time. The fourth sentence in this section should be revised to read, "-Pfa..i.f+e Healthy plantings for the most part, will quickly out compete annual weeds." The last sentence in this section states that areas will be reseeded if large weed infestations occur. Please clarify how and when boom spraying would be used as part of this plan. If adaptive management is conducted, it is unlikely that there would be an opportunity for a large infestation to become established and/or require boom spraying. However, mowing, as proposed, is not likely to be sufficient to control Canada thistle or common tansy. These are problematic species that should be controlled prior to bud break {May/June) with spot treatments of herbicide. If Canada thistle or common tansy become established to a point that would require boom spraying, only infested areas should be sprayed and avoidance of overspray into non-infested areas should clearly be described. Vegetation Management Techniques A plan describing the type of maintenance that will be used (e.g., grazing prescribed burn, etc.) should be developed for each site. If grazing is used, the stocking rate and pasture rotation should be provided. Care 2

3 should be taken to not overgraze the site as the disturbed areas can allow unwanted weed seeds to germinate. Animals used for grazing can introduce/deposit invasive or noxious weed seeds that can become established at the solar facility. The animals should be held in a pasture or location that does not contain invasive or noxious weeds for a minimum of four days prior to introduction to the solar facility. Mowing -To be successful, mowing must be done in a specific way. To manage invasive or noxious plants, the DNR recommends spot-mowing only in areas where these plants occur, rather than mowing the entire site. Additionally, the timing of mowing is critical. For example, if mowing occurs when some weeds have already flowered, then native plants may end up being mowed as well. If native plantings are mowed repeatedly, the plantings may fail, resulting in poor establishment. This section needs clarification regarding the type of mowing proposed, the intended use and purpose of the mowing, and its expected frequency. As currently stated, it seems that broad, site-wide mowing would be conducted routinely, including every time the vegetation reaches a height of 20 inches. This is counter to native plant management. This section needs clarification, which could be accomplished by referencing the DNR's Prairie Establishment & Maintenance Technical Guidance for Solar Projects (Pages 6-7). This guidance document includes specific recommendations for when these maintenance activities would take place: solar tech guidance.pdf The second sentence of the second paragraph in this section should be revised to read, "It may be necessary to mow low areas when conditions are dry either ahead of or after ideal mowing times due to rain events ahead of the ideal mowing schedule, or mowing may be avoided altogether." Although mowing is an acceptable maintenance method, it is only necessary if there are problematic weeds or shade competition issues. In most cases, wet areas will not need to be mowed. Herbicide Treatment-This section should clarify that herbicides will not be broadcast sprayed. The DNR recommends that spot-treatment be used only as necessary to target invasive or noxious weeds and not as a general vegetation management strategy. Supplemental Seeding - The Vegetation Disturbance section states that low impact disturbances may recover on their own, or may require over-seeding. However, the first paragraph of the Supplemental Seeding section states that areas continually impacted by maintenance activities (traffic areas) will not be reseeded, but weeds will be managed. This paragraph should be revised to address continually impacted areas and the following text should be added, "To stabilize soil, these areas should be seeded with species that can tolerate a higher level of disturbance. Otherwise, undesirable weeds will grow in these areas and will need to be controlled every year. Alternatively, continually compacted areas could be stabilized with gravel or matting to prevent rutting and erosion issues." The second paragraph of this section needs several modifications. First, the text indicates that seed failure can occur due to poor quality seed. While this may be true in some restorations, it is improbable in cases where the seed is being purchased. All seed purchased from a reputable seed company requires seed testing and the purity and germination information is included on the seed tag. If seed is planted soon after it is received, seed failure due to poor quality is unlikely. 3

4 Second, this paragraph states that it may be necessary to adjust the seed mix species to best fit the growing conditions of an area. However, this type of adjustment should be done in the seed mix development phase for each site based on the individual site characteristics (soil moisture, rainfall, slopes, soil type, etc.}. This section should be revised to include a commitment to working with an experienced restoration company to develop a seed mix suitable for site conditions prior to seeding the site. Finally, this paragraph states that highly erosive areas may require a fast-growing mix that may be non-native. This language needs to be revised to identify specific sites where fast-growing non-natives may be needed to control erosion and what types of non-native species are proposed for use. This section should be revised to include language that clarifies that, in the event that a non-native mix is used, it will be selected so as not to compete with the native mixes, but will remediate erosion issues. Per Section 5.1 of the AIMP/VMP, the DNR anticipates continued coordination with Aurora to identify seed mixes and seeding methods appropriate for each facility. Soil Management- It would be helpful for this section to include examples of standard erosion control techniques that are proposed for use. The DNR cautions that if natives are going to be seeded into the winter wheat areas, there can be issues with allelopathy with the native species. Oats are an exception to this issue. DNR recommends revising the proposed use of erosion control blankets on top of oats and native mixes. If the site is not highly erodible land or does not have steep slopes, this proposed action seems unwarranted and to be an unnecessary extra step and expense. Based on the current document, it is unclear whether erosion control materials other than erosion control blankets would be used. Seeding Mixes The DNR has reviewed the seeding mixes for the Aurora Solar Project and offers the following comments and recommendations: General To expedite review of the seeding mixes proposed for use, it would be helpful to receive the seed mixes as a spreadsheet file. The seed mix spreadsheet should include seeds per square foot so our agency can better evaluate whether or not they meet the standards established in the DNR's Prairie Establishment & Maintenance Technical Guidance for Solar Projects. To better address seed shortage issues, difficulties with establishment under the panel areas, and ease of access of solar equipment in the short-term, the owner may identify areas with mesic or dry soils that have the aforementioned issues. With DNR approval, area seed mixes may be supplemented with creeping red fescue (Festuca rubra) as part of the seed mix used under the panel array. This species should not be used between the panel arrays or in other seeding areas. Prairie Mix-Mesic Soils The DNR has specific recommendations regarding coneflower in the prairie mix. E. purpurea or a similar species should be used in place of E. pa/iida because E. purpurea is native to Minnesota, while E. pa/iida is not. Also, 4

5 please clarify why the mix has three early-blooming species as opposed to the requested five species (e.g, seed supply shortage, cost of mix, etc.). Array Mix-Sandy Soils Only 14 forb species are included in this mix instead of 20, as recommended in the DNR's Prairie Establishment & Maintenance Technical Guide for Solar Projects. Please provide an explanation for why this is necessary (e.g, seed supply shortage, cost of mix, etc.). Array Mix-Heavy Soils Showy goldenrod {Solidago speciosa) is normally found on more mesic to dry sites. Please provide justification for using it on the heavy soils site, such as whether there has been demonstrated success of this manner of use. If such justification is lacking, an alternative goldenrod species should be used instead of Solidago speciosa. Only 17 species of forbs are included in this mix instead of the requested 20. Please provide an explanation for why the full complement of 20 species is not included (e.g., seed supply shortage, cost of mix, etc.). The DNR appreciates the opportunity to comment on Aurora Sola r's vegetation management documents. If you have any questions, please contact me at Sincerely, /1,._;) j ~~/AJ:yadet?'-._.J Cynthia Warzecha Principal Planner CC: Suzanne Steinhauer, Minnesota Department of Commerce Jacob Fehlen, Enel Green Power Jacob Thompson, Barr Engineering ERDB