S tormwater S takeholder Advisory Committee Derry Township Municipal Authority S tormwater Management Program Meeting #8 - October 5, 2016 Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE L I ABL Y RE S PONS I VE L Y PROF E S S I ONAL L Y
Agenda 1. Pollution Reduction Plans (PRP) 2. Credit Policy Development Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE L I ABL Y RE S PONS I VE L Y PROF E S S I ONAL L Y
Pollution Reduction Plans Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE RE L L I I ABL ABL Y Y RE RE S S PONS PONS I I VE VE L L Y Y PROF PROF E E S S S S I I ONAL ONAL L L Y Y
Mapping Mapping has been a requirement of the MS4 permit, so what’s new? 1. Land Use • Category • Pervious/ Impervious 2. S t orm S ewersheds 3. Locat ions of proposed st ruct ural BMPs The first t wo help us develop our baseline pollut ion level The t hird t ells us where and how we’ re going t o meet our impairment reduct ions Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE L I ABL Y RE S PONS I VE L Y PROF E S S I ONAL L Y
What’s a S torm S ewershed? • Think of it as a t ype of wat ershed • Out let point is a st ormwat er out fall • Upslope cont ribut ing area is dict at ed by t opography and inlet s/ pipe net work • Wat ersheds are fairly simple t o delineat e, but st orm sewersheds t ake a lit t le more t ime • Because t he area is defined by t he cont ribut ing infrast ruct ure, one must have t hat infrast ruct ure accurat ely mapped first Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE L I ABL Y RE S PONS I VE L Y PROF E S S I ONAL L Y
Mapping Why is all this new stuff needed? • New permit requires the completion of Pollution Reduction Plans (PRP) • S ets specific reduction targets for local impaired streams • S iltation - 10% sediment reduction • Nutrient - 5% phosphorus reduction • New mapping components give inputs necessary to calculate existing load baseline and tell us where we need to implement reductions Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE L I ABL Y RE S PONS I VE L Y PROF E S S I ONAL L Y
What’s our Baseline? It Depends… • The quick and dirty… • Derry Township has 10,540 acres defined as Urban Area • 25% defined as Impervious (2,626 acres) • 75% defined as Pervious (7,878 acres) • The rest of Derry Township has 4,180 acres • 18% defined as Impervious (752 acres) • 82% defined as Pervious (3,428 acres) • Loading rate for Dauphin County • Impervious Developed (S ediment): 1,999.14 lbs/ acre/ yr • Pervious Developed (S ediment): 299.62 lbs/ acre/ yr Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE L I ABL Y RE S PONS I VE L Y PROF E S S I ONAL L Y
Let’s Do S ome Math IMPERVIOUS PERVIOUS TOTAL 2,626 acres UA x 1,999.14 lbs/ acre/ yr = 7,878 acres UA x 299.62 lbs/ acre/ yr = 5,249,742 lbs/yr 2,360,406 lbs/yr 7,610,148 lbs/yr 752 acres UA x 1,999.14 lbs/ acre/ yr = 3,428 acres UA x 299.62 lbs/ acre/ yr = 1,503,353 lbs/yr 1,027,097 lbs/yr 2,530,450 lbs/yr Is this our number? ? ? 10,140,598 lbs/yr Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE L I ABL Y RE S PONS I VE L Y PROF E S S I ONAL L Y
What’s our Baseline? It Depends… • Our MS 4 baseline – not so quick and dirty… • Defined as our “ Planning Area” 1. Within the boundaries of your municipality; and 2. Within your MS 4-regulated storm sewershed; and 3. Within your Urbanized Area and/ or Upstream of your Urbanized Area • To meet the MS 4 requirements, only the planning areas matter • Therefore, we must focus our required reductions in these areas • For overall environmental quality, non-planning areas still matter • We need a completed infrastructure map to do this analysis Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE L I ABL Y RE S PONS I VE L Y PROF E S S I ONAL L Y
What Can Be Excluded From the Planning Area? • Area outside the MS 4-regulated storm sewershed • Area downstream of the Urbanized Area • Area within the MS 4-required planning area, but has a stormwater permit • NPDES Industrial permits • Non-municipal MS 4s Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE L I ABL Y RE S PONS I VE L Y PROF E S S I ONAL L Y
What’s our Baseline? • Once we determine our MS 4 planning area we calculate pollutant loads similar to our simplified example • This is our baseline with a caveat… • We can reduce the baseline within our MS 4 planning area based on existing BMPs (BMPs in place as of the PRP reporting date) • Previous guidance from DEP indicated reductions might only come from more recent BMPs • Current guidance says ALL existing BMPs can be used… with some caveats • BMP has to be functioning (up-to-date O&M) • BMP must be documented in permit application (Need performance information) Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE L I ABL Y RE S PONS I VE L Y PROF E S S I ONAL L Y
Calculating the Final Baseline Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE L I ABL Y RE S PONS I VE L Y PROF E S S I ONAL L Y
Final Baseline Established – Next S teps • Need to group storm sewersheds into those draining into impaired waters and those that don’ t drain into impaired waters • Derry Township has three Appendix E impairments (need PRPs) • Unnamed Tributaries to S watara Creek - S iltation • S pring Creek - S iltation • Iron Run – S iltation • A PRP will need to be developed for each of these local impairments • We will be required to reduce sediment by 10% in storm sewersheds contributing to each of these impaired waters Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE L I ABL Y RE S PONS I VE L Y PROF E S S I ONAL L Y
Final Baseline Established – Next S teps • In addition to our local impaired waters, we need to address our Chesapeake Bay Pollution Reduction Plan (CBPRP –Appendix D) • This requires us to reduce sediment by 10% , phosphorus by 5% , and nitrogen by 3% • DEP has an agreement with EP A that if we reduce sediment by 10% then we also have reduced phosphorus and nitrogen by at least 5% and 3% , respectively. Basically, we need to reduce sediment by 10% to be in compliance. • The 10% for the local PRPs is calculated from only those sewersheds contributing to the impaired water • S ince our entire Township is in the Chesapeake Bay Watershed, we calculate the 10% needed to meet the CBPRP from ALL MS 4 storm sewersheds • Any reductions used to meet the local PRPs can be subtracted from the CBPRP reduction goal • BMPs to address the needed CBPRP reductions can be placed in any of the MS 4 storm sewersheds Pro viding a c o st e ffe c tive pub lic se rvic e to pro te c t a nd e nha nc e the wa te re nviro nme nta nd q ua lity o f life fo ro urlo c a la nd re g io nalc o mmunity RE L I ABL Y RE S PONS I VE L Y PROF E S S I ONAL L Y
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