Stormwa­ter, zon­ing guard from dis­as­ter

The Calvert Recorder - - Front Page - By TA­MARA WARD tward@somd­news.com

As Hous­ton and other parts of Texas, Louisiana, Tennessee and Kentucky try to re­cover in the af­ter­math of Hurricane Har­vey, lo­cal ju­ris­dic­tions are won­der­ing if they, too, can han­dle a se­vere rain event of the same mag­ni­tude.

“You’re never go­ing to con­vey that much wa­ter off of the streets and put it back into rivers and trib­u­taries that are al­ready swelled,” said Calvert County Plan­ning and Zon­ing Direc­tor Mark Wil­lis, re­fer­ring to the re­ported 33 tril­lion gal­lons of wa­ter that fell along the Gulf of Mex­ico dur­ing Hurricane Har­vey.

“I think Mother Na­ture took her gloves off on this one and

she said ‘I’ll show you who’s in charge,’” added Wil­lis.

Post-Har­vey, there were sev­eral sug­ges­tions that wild growth due to poor plan­ning and zon­ing, as well as stormwa­ter man­age­ment de­fi­cien­cies, made Hous­ton’s flood­ing worse.

“They are mar­ried. They can­not be sep­a­rate. They have to go to­gether,” stressed Wil­lis, re­fer­ring to zon­ing and stormwa­ter man­age­ment reg­u­la­tions. “[You] don’t have a choice.”

Wil­lis said zon­ing is the law of how peo­ple use your land, once they get per­mis­sion to build some­thing within the plan­ning process, and that zon­ing is im­por­tant in mit­i­gat­ing fu­ture dis­as­ters by de­ter­min­ing what con­struc­tion is al­lowed within cer­tain ar­eas.

Man­ag­ing stormwa­ter

Wil­lis, who pre­vi­ously served as deputy direc­tor of en­ter­prise fund op­er­a­tions un­der the Depart­ment of Public Works with some purview over stormwa­ter man­age­ment, ex­plained stormwa­ter man­age­ment is the tech­nique used to di­rect the wa­ter else­where.

When de­vel­op­ing a par­cel of prop­erty into an apart­ment building, with as­phalt park­ing lots and side­walks — im­per­me­able sur­faces that will not ab­sorb wa­ter — a developer must en­gi­neer sys­tems to di­rect wa­ter else­where, said Wil­lis. Stormwa­ter man­age­ment would be re­quired for a house be­ing built on a hill and other struc­tures on var­i­ous el­e­va­tions be­cause the land was changed and there is less land to ab­sorb wa­ter.

“You want to be able to con­vey wa­ter away in the most ef­fi­cient way pos­si­ble,” Wil­lis said.

The plan­ning head said he took a look at Hous­ton’s stormwa­ter man­age­ment reg­u­la­tions and liked what he read. He be­lieves the regs would have worked 99.9 per­cent of time, but not with the amount of rain from the hurricane.

“With Har­vey, [Hous­ton] wasn’t go­ing to win that. I don’t care what stormwa­ter man­age­ment they put into place — they still are go­ing to have flooded streets,” said Wil­lis.

Public Works Depart­ment Deputy Direc­tor of En­gi­neer­ing and High­ways Danielle Con­row said proper zon­ing and stormwa­ter man­age­ment prac­tices can help lessen the im­pact of flood­ing or heavy rain events, but con­curred with Wil­lis that no ju­ris­dic­tion is pre­pared for the amount of pre­cip­i­ta­tion Hous­ton ex­pe­ri­enced. In some ar­eas of Texas, nearly 40 to 53 inches of rain fell over a pe­riod of four days dur­ing Har­vey.

“Calvert County’s roads are de­signed to­day to con­vey stormwa­ter up to a rate of 5.3 inches over a 24-hour pe­riod. In some cases, ag­ing in­fra­struc­ture may con­vey stormwa­ter at a slower rate,” re­ported Con­row, who ex­plained the amount of man­age­able rain­fall per hour de­pends on a com­bi­na­tion of fac­tors, in­clud­ing re­cent weather, the soil type for the area, sur­round­ing slopes, land el­e­va­tion and the de­sign stan­dards of the stormwa­ter man­age­ment in­fra­struc­ture at the time of con­struc­tion.

“Keep in mind when the first 10 inches of rain falls on day one, the ground is now sat­u­rated and runoff is still seep­ing into con­veyance struc­tures. That means the next 10 inches of rain has a greater im­pact — fol­lowed by day three and day four,” ex­plained Wil­lis, sug­gest­ing that the wind shear that is pos­si­bly push­ing the Ch­e­sa­peake Bay wa­ters land­ward caus­ing flood­ing with­out rain would also have to be taken into con­sid­er­a­tion.

Wil­lis be­lieves that with 10 inches of rain, there would be flood­ing on many roads and prop­er­ties dur­ing the ac­tual rain event, but the county could still be ac­cessed cau­tiously in most ar­eas. Con­row added that ground sat­u­ra­tion con­trib­utes to the stormwa­ter runoff as well.

Plan­ning for den­sity, vul­ner­a­bil­i­ties

“We are in no way ever go­ing to reach the den­sity of Hous­ton, ob­vi­ously … and any de­vel­op­ment that we do, whether it’s an in­di­vid­ual res­i­dence or it’s a com­mer­cial building, here all of them have to ad­dress stormwa­ter man­age­ment,” stressed Wil­lis.

He said zon­ing is im­port- ant in mit­i­gat­ing fu­ture dis­as­ters by de­ter­min­ing what con­struc­tion is al­lowed within cer­tain ar­eas. Part that re­quires us­ing en­vi­ron­men­tal reg­u­la­tions to pro­vide guid­ance on the al­low­able den­sity in flood­prone ar­eas.

Con­row said any area with low-ly­ing and flat land is vul­ner­a­ble to heavy rain events due to ris­ing wa­ter lev­els. High wa­ter lev­els not only cause flood­ing directly, but also pre­vent storm drain sys­tems from con­vey­ing stormwa­ter prop­erly un­til the wa­ter level low­ers.

“Calvert is more vul­ner­a­ble on the shores. You don’t even need Har­vey to cause that,” said Wil­lis, adding that a heavy wind dur­ing a high tide could flood out the crit­i­cal ar­eas, those within 1,000 feet of the wa­ter.

Right now in Calvert there are sev­eral ar­eas iden­ti­fied as flood prone, for which the county has com­pleted or be­gun stud­ies, and com­pleted or drafted poli­cies: Cove Point, Broomes Island, Neeld Es­tates/Breezy Point, Ch­e­sa­peake Beach/North Beach and Solomons Island.

There are 17,123 parcels of land in the crit­i­cal area, ac­cord­ing to Wil­lis. Roughly 8,144 have struc­tures built on them. Wil­lis stressed that the crit­i­cal area may not be dam­aged by wa­ter, but may be dam­aged by wind or wind-borne ob­jects. “Ei­ther way, a hurricane like Har­vey could cause this dam­age and no amount of zon­ing could pre­vent that,” said Wil­lis.

How­ever, there are ways to mit­i­gate.

Wil­lis said peo­ple have to be very care­ful about how they sit­u­ate houses in those ar­eas. For those who want to build in flood­prone ar­eas in the county, they will have to build their house in an “el­e­vated sta­tus” that will al­low flood wa­ters to pass through and around the bot­tom sec­tion of the home.

Wil­lis said in ar­eas where it is “fi­nan­cially tough” to save homes, houses are ei­ther el­e­vated or de­mol­ished with the use of grants from the Fed­eral Emer­gency Man­age­ment Agency. The de­mo­li­tion is to phys­i­cally re­move those struc­tures from the flood­prone ar­eas so their de­bris is not a haz­ard to other homes and res­i­dents.

To date, the county has raised three homes and de­mol­ished one home within crit­i­cal area us­ing the FEMA grants. With a new grant wait­ing, there are plans to el­e­vate four more houses and de­mol­ish three more, sub­se­quent to ap­proval from FEMA.

Par­tic­i­pa­tion in such ef­forts is purely vol­un­tary and many peo­ple elect not to par­tic­i­pate be­cause they have to bear 25 per­cent of the cost. The grant cov­ers the other 75 per­cent.

In ad­di­tion to shoul­der­ing the cost, peo­ple have to be will­ing to ac­cept a change in what their res­i­dence looks like and how they ac­cess it, which may be prob­lem­atic for some­one with a dis­abil­ity. The county will not force home­own­ers to raise or de­mol­ish their homes. How­ever, any new con­struc­tion, even for ex­ist­ing home­own­ers who may have lost their house to a dis­as­ter, would have to ad­here to new reg­u­la­tions re­quir­ing homes be el­e­vated.

For the ar­eas in the county not prone to flood­ing, Wil­lis said “all bets of off” in a Hurricane Har­vey-type event, but said that the county won’t ex­pe­ri­ence com­pletely sub­merged build­ings be­cause of Calvert’s el­e­va­tion, which is not flat like Hous­ton.

“If we got a heavy rain, can we con­vey the wa­ter? Yes,” Wil­lis con­fi­dently re­sponded, re­fer­ring to a pos­si­ble rain event not of bib­li­cal pro­por­tions. “I guess it’s unique for us be­cause [we] can’t do that in Broomes Island, but we can in Prince Fred­er­ick.”

Plan­ning and zon­ing, in con­cert with the county’s Depart­ment of Public Safety, Emer­gency Man­age­ment Di­vi­sion, is work­ing on a coun­ty­wide flood mit­i­ga­tion plan and haz­ard mit­i­ga­tion plan to im­prove Calvert’s re­sis­tance to nat­u­ral haz­ards, to in­clude flood­ing.

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